Åttonde Nordiska Dricksvattenkonferensen - Svenskt Vatten

Åttonde Nordiska 

Dricksvattenkonferensen 

Stockholm den 18–20 juni 2012 

Föredrag 

NORDIWA

På CD-skivan finns pdf- och 

powerpointfiler från föreläsningarna. 

Innehållsförteckningen visar hur filerna är namngivna

Förord 

Denna dokumentation innehåller föredrag och posterpresentationer från den 8:de 

Nordiska Dricksvattenkonferensen. Konferensen hålls i Stockholm 18–20 juni 2012. 

Den Nordiska dricksvattenkonferensen är ett forum för utbyte av erfarenheter och kunskaper 

mellan personer verksamma inom dricksvattenteknik i de nordiska länderna, både 

driftansvariga vid vattenverk, rådgivare och leverantörer till branschen samt forskare och 

myndigheter. Den är ett utmärkt tillfälle att ta del av pågående forskning samt träffa kolleger 

och diskutera gemensamma problem; stora delar av Norden har ju likartad vattenkvalitet 

även om tillgången på olika typer av råvatten är olika. Konferensen arrangeras vartannat 

år och är ett samarbete mellan ländernas branschorganisationer och NORDIWA (nordiska 

nätverket under IWA – International Water Association). Konferensen går runt bland de 

nordiska länderna, 2012 står Svenskt Vatten som arrangör. 

2012 års konferens handlar till stor del om säkerhet, både om ett säkert sätt framställa 

dricksvatten och att bibehålla kvaliteten i ledningsnätet. Programmet är indelat i fyra 

områden: management, säkerhet inom dricksvattenproduktionen, dricksvattenkvalitet 

och ledningsnät. Flera föredrag tar upp virus, från detektion och analys till källspårning, 

säkerhetsplanering och reningsmetoder. Reningsmetoder som avhandlas är bl.a. mixed 

bed-filtrering, ultrafilter och snabbsandfilter. Övervakning av kvaliteten både i råvatten och 

i distributionssystem tas upp i ett par föredrag. Annat som presenteras är användning av 

Dopplerteknik för kontroll av läckage och om hälsan påverkas av lättflyktiga ämnen från 

PEX-rör. 

Programmet har utifrån inkomna förslag satts ihop av en programkommitté bestående av: 

Charlotte Frambøl, Danva, Danmark 

Annika Lindholm, Nordvand, Danmark 

Riina Liikanen, VVY, Finland 

Veli-Pekka Vuorilehto, HSY, Finland 

Gústaf Adolf Skúlason, Samorka, Island 

Kjetil Furuberg, Norsk Vann, Norge 

Vidar Lund, FHI, Norge 

Gullvy Hedenberg, Svenskt Vatten Sverige 

Daniel Hellström, Svenskt Vatten, Sverige 

Johanna Ansker, Stockholm Vatten, Sverige 

Utöver föredragsprogram och posterutställning görs ett studiebesök på Görvälnverket som 

distribuerar dricksvatten till 14 kommuner i norra Storstockholm. Kommunalförbundet 

Norrvatten ansvarar för vattenverket, som ligger i Järfälla kommun och tar råvatten från 

Mälaren. 

Under konferensen utdelas också årets ”The pumphandle award”. Det kommer från The 

John Snow Society, en organisation som arbetar med kvalitet och säkerhet inom dricksvattenförsörjning. 

John Snow var den som 1854 utförde den första epidemiologiska studien 

i världen, vilken kom fram till att kolera spreds med dricksvatten. Genom att se till att ett 

pumphandtag togs bort vid en misstänkt brunn fick han en pågående epidemi att upphöra. 

Stockholm juni 2012 

Gullvy Hedenberg

Innehåll 

Program 

Posterutställning 

Sida CD-numrering 

Session 1- Management 

Drick kranvatten – utvärdering och handledning 

av ett kommunikationsprojekt 9 1-1 

Implementering av managementsystem i vattentjänstföretag 15 1-2 

Regional riskbedömning av dricksvattenförsörjning 23 1-3 

Exempel på och erfarenheter av svenska arbetsmetoder för HACCP 31 1-4 

Benchmarkingmodell för dricksvattenförsörjning i Sverige 36 1-5 

Session 2- Säker dricksvattenförsörjning 

Riskhantering i vattenförsörjningen 42 2-1 

Förbättrad SCADA-säkerhet vid dricksvattenanläggningar 47 2-2 

Hantering av känslig information inom dricksvattenförsörjningen 

QMRA som stöd i säkerhetsplaneringen – minskning och 

55 2-3 

hantering av risk för norovirus via dricksvatten 

Kan klordioxid fungera som hygienisk barriär i 

58 2-4 

interna distributionssystem? 

Samband mellan nederbörd uppströms ett dricksvattenverk 

62 2-5 

och samtal till sjukvårdsupplysningen gällande mag-tarm symtom. 67 2-6 

VISK – Minskad risk för vattenburen smitta trots förändrat klimat 71 2-7 

Erfarenheter från workshopar om GDP och MRA 75 2-8 

NORVID projektet – analys av norovirus i dricksvatten 80 2-9 

Detektion av adenovirus i floden Glomma 85 2-10 

Ultrafilter – en oberoende mikrobiologisk barriär 

Modellering, övervakning och källspårning av 

86 2-11 

mikrobiologiska risker i råvatten 94 2-12

Innehåll 

Sida CD-numrering 

Session 3- Dricksvattenkvalitet 

Övervakning av förändringar av vattenkvaliteten i distributionssystem 

Nya metoder för on-line-detektering av mikrobiologisk 

100 3-1 

dricksvattenkvalitet 

Effekten av förbättrad vattenrening på mikroorganismer i Oslos 

105 3-2 

distributionssystem för vatten 115 3-3 

Mixed bed-filtrering i ytvattenrening 123 3-4 

Dricksvattenkriser berör oss alla! 131 3-5 

Ökad kunskap om snabbsandfilter 

Förändringar i sammansättningen av organiskt kol under 

133 3-6 

dricksvattenproduktion 

Analys av bakteriestammar i biofilmer i dricksvattennät i 

138 3-7 

södra Sverige 

Avancerad analys av hålrumsmembran i pilotförsök med 

142 3-8 

UF/koagulering 146 3-9 

Praktiska erfarenheter av avhärdning i fluidiserad bädd 151 3-10 

Session 4- Distributionssystem 

Förbättrad läckagekontroll genom Dopplerteknik och tryckreglering 156 4-1 

On-line-simulering av distributionssystem för dricksvatten 

Aqua fingerprint – en metod för att karakterisera löst organiskt 

161 4-2 

material i dricksvatten 165 4-3 

Påverkar lättflyktiga organiska ämnen från PEX-rör hälsan? 

Identitet och nedbrytbarhet för organiska ämnen från 

169 4-4 

PEX-rör i byggnader 

Sektionering i Hvidovre Forsyning – planering, 

173 4-5 

genomförande och övervakning 176 4-6 

Relining av huvudledningar och byggnadsinstallationer 

Säker dricksvattenkvalitet i vattenledningsnätet: 

184 4-7 

Åtgärder för att upprätthålla trycket i ledningsnätet 189 4-8 

Inträngning av markföroreningar i distributionsnätet 199 4-9 

Svensk utveckling av material i kontakt med dricksvatten 203 4-10

Program • Tisdag 19 juni 

10.00 Välkomstanförande 

Lena Söderberg, Svenskt Vatten. 

Session 1: Management 

Ordförande: Charlotte Frambøl, Danva. 

Drick kranvatten – utvärdering och 

handledning av ett kommunikationsprojekt 

Nordkvist-Persson M, Sydvatten. 

Implementering av managementsystem i vattentjänstföretag 

Rosen Balder C, Schmidt S, Sidenius S, NIRAS. 

Regional riskbedömning av dricksvattenförsörjning 

Lindhe A, Rosén L, Pettersson T, Chalmers. 

Bergstedt O, Chalmers, Göteborg Vatten. Nordensten C, Livsmedelsverket. 

Exempel på och erfarenheter av svenska arbetsmetoder för HACCP 

Bennet M, WSP Sweden AB. 

Posterpresentation 

Benchmarkingmodell för dricksvattenförsörjning i Sverige 

Bondelind M, Pettersson T J R, Chalmers. Malm A, Bergstedt O, 

Göteborg Vatten. Lindgren J, Svenskt Vatten. 

Lunch 

13.00 Session 2: Säker dricksvattenförsörjning 

Ordförande: Riina Liikanen, Finlands vattenverksförening (VVY). 

Riskhantering i vattenförsörjningen 

Corfitzen C B, Albrechtsen H-J, Arnbjerg-Nielsen, Danmarks Tekniska 

Universitet. Andersen H S, Jørgensen C. DHI. Jacobsen P, Århus Vand A/S. 

Mollerup F, VandCenter Syd A/S. Lind S, Københavns Energi A/S. 

Heidemann G, Naturstyrelsen. Jensen R, Odense Kommune. 

Förbättrad SCADA-säkerhet vid dricksvattenanläggningar 

Johansson E, Kungliga Tekniska Högskolan. 



Wikström A-S, Vatten & Miljöbyrån AB. 

QMRA som stöd i säkerhetsplaneringen – minskning 

och hantering av risk för norovirus via dricksvatten 

Petterson S, Seidu R, Vraale L, Heistad A, Universitet för miljö- 

och biovetenskap. Ottoson J, Sveriges Lantbruksuniversitet.

Program • Tisdag 19 juni 

Kan klordioxid fungera som hygienisk 

barriär i interna distributionssystem? 

Tryland I, Wenneberg A C, Liltved H, NIVA. 

Samband mellan nederbörd uppströms ett dricksvattenverk 

och samtal till sjukvårdsupplysningen gällande mag-tarm symtom. 

Tornevi A, Forsberg B, Umeå Universitet. 

VISK – Minskad risk för vattenburen smitta trots förändrat klimat 

Blom L B, Friberg J, Kretsloppskontoret, Göteborg. Furuberg K, Norsk 

Vann. Lindgren P-E, Linköpings Universitet. Morrison G M, Chalmers. 

Myrmel M, Norges Veterinärhögskola. Ottosson J, Statens Veterinärmedicinska 

anstalt. Schultz A C, Danmarks Tekniska Universitet. 

Sal L S, Nedre Rommerike Vannverk. Simonsson M, Livsmedelsverket. 

Kaffe 

Ordförande: Veli-Pekka Vuorilehto, Helsingforsregionens miljötjänster (HSY) 

15.00 Erfarenheter från workshopar om GDP och MRA 

Heinicke G, DHI. Abrahamsson J, Almqvist H, Athley L, Göteborg 

Vatten. Häggström P, Stockholm Vatten. Pott B-M, Sydvatten. 

Hedenberg G, Svenskt Vatten. 

NORVID projektet – analys av norovirus i dricksvatten 

Nyström F, Lindgren P-E, Linköpings Universitet. Ansker J, Häggström P, 

Stockholm Vatten. Ericsson P, Norrvatten. Athley E, Göteborg Vatten. 

Pott B-M, Sydvatten. 

Detektion av adenovirus i floden Glomma 

Rosado R C, Myrmel M, Norges Veterinärhögskola. 

Ultrafilter – en oberoende mikrobiologisk barriär 

Almqvist H, Rydberg H, Bergstedt O, Kjellberg I, Johansson A, 

Göteborg Vatten. 


Modellering, övervakning och källspårning 

av mikrobiologiska risker i råvatten 

Sokolova E, Pettersson T J R, Chalmers. Åström J, Tyréns AB. 

Bergstedt O, Chalmers, Göteborg Vatten. Kjellberg I, Göteborg Vatten. 

Hermansson M, Göteborgs Universitet. 

16.30 John Snow Society 

Om John Snow, prisutdelning samt ”pump handle” föredrag. 

19.00 Konferensmiddag

Program • Onsdag 20 juni 

09.00 Session 3: Dricksvattenkvalitet 

Ordförande: Johanna Ansker, Stockholm Vatten. 

Övervakning av förändringar av vattenkvaliteten i distributionssystem 

Ikonen J, Juntunen P, Miettinen I T, Institutet för hälsa och välfärd (THL). 

Nya metoder för on-line-detektering 

av mikrobiologisk dricksvattenkvalitet 

Bjergaarde N E, Københavns Energi. Lindholm A, Nordvand. 

Hansson E, Roskilde Forsyning. 

Effekten av förbättrad vattenrening på 

mikroorganismer i Oslos distributionssystem för vatten 

Hem L J, SINTEF. Lund V, Anderson-Glenna A, Folkehelseinstituttet. 

Skaar I, Veterinaerinstituttet. 

Kaffe 

10.30 Mixed bed-filtrering i ytvattenrening 

Härkki H, Hiillos K, Helsingforsregionens Miljötjänster. 

Dricksvattenkriser berör oss alla! 

Nyström P-E, Nordensten C, Livsmedelsverket, Abrahamsson E-M, AKRAB 

Ökad kunskap om snabbsandfilter 

Albrechtsen H-J, Gülay A, Lee C, Tatari K, Lin K, Musovic S, Smets B F, 

Danmarks Tekniska Universitet. Boe-Hansen R, Borch Nielsen P, Krüger. 

11.30 Posterpresentation 

Förändringar i sammansättningen av 

organiskt kol under dricksvattenproduktion 

Lavonen E, Köhler S J, Sveriges Lantbruksuniversitet. Tranvik L, 

Uppsala Universitet. Gonsior M, Linköpings Universitet. Ansker J, 

Stockholm Vatten. 

Analys av bakteriestammar i biofilmer i dricksvattennät i södra Sverige 

Lührig K, Persson K M, Lunds Universitet, Sydvatten. 

Canbäck B, Johansson T, Tunlid A, Rådström P, Lunds Universitet. 

Avancerad analys av hålrumsmembran i pilotförsök med UF/koagulering 

Keucken A, VIVAB. Donose B C, The University of Queensland. 

Persson K M, Sydvatten. 

Praktiska erfarenheter av avhärdning i fluidiserad bädd 

Midlöv E, VA SYD. McCleaf P, Uppsala Vatten och Avfall. 

Pott B-M, Persson K M, Sydvatten.

Program • Onsdag 20 juni 

Lunch 

13.20 Session 4: Distributionssystem 

Ordförande: Kjetil Furuberg, Norsk Vann 

Förbättrad läckagekontroll genom Dopplerteknik och tryckreglering 

Ekblad T, Moberg F, Göteborg Vatten. 

On-line-simulering av distributionssystem för dricksvatten 

Aksela K, Aalto Universitet. 


Aqua fingerprint – en metod för att 

karakterisera löst organiskt material i dricksvatten 

Boe-Hansen R, Krüger. Stedmon C, Arvin E, 

Danmarks Tekniska Universitet. 


Lund V, Anderson-Glenna M, Steffensen I-L, Folkehelsoinstituttet. 

Skjevrak I, Statoil. 

Identitet och nedbrytbarhet för 

organiska ämnen från PEX-rör i byggnader 

Arvin E, Albrechtsen H-J, Corfitzen C B, Jelinkóva Z, Lützhøft H-C H, 

Olsson M E, Ryssel S T, Waul C K, Danmarks Tekniska Universitet. 

Kaffe 

15.00 Sektionering i Hvidovre Forsyning 

– planering, genomförande och övervakning 

Isager Hedegaard L, Hvidovre Forsyning. Jansen G M, Eiris M B, ALECTIA. 

Relining av huvudledningar och byggnadsinstallationer 

Pelto-Huikko A, Kaunisto T, WANDER. 


Åtgärder för att upprätthålla trycket i ledningsnätet 

Mosevoll G, Skiens kommun. 


Inträngning av markföroreningar i distributionsnätet 

Bäckström M, Eklund M, Wikström A-S, Vatten & Miljöbyrån. 

Svensk utveckling av material i kontakt med dricksvatten 

Rod O, Swerea KIMAB. 

16.20 Sammanfattning


Postrar knutna till posterpresentationer 


Bondelind M, Pettersson T J R, Chalmers, Malm A, Bergstedt O, Göteborg Vatten, Lindgren J, Svenskt Vatten. 


Wikström A-S, Vatten & Miljöbyrån AB. 

QMRA som stöd i säkerhetsplaneringen – minskning 

och hantering av risk för norovirus via dricksvatten 

Petterson S, Seidu R, Vraale L, Heistad A, Universitet för miljö- och biovetenskap, 

Ottoson J, Sveriges Lantbruksuniversitet. 

Kan klordioxid fungera som hygienisk barriär i interna distributionssystem? 

Tryland I, Wenneberg A C, Liltved H, NIVA. 

Samband mellan nederbörd uppströms ett dricksvattenverk och 

samtal till sjukvårds upplysningen gällande mag-tarmsymtom. 

Tornevi A, Forsberg B, Umeå Universitet. 

VISK – Minskad risk för vattenburen smitta trots förändrat klimat 

Blom L B, Friberg J, Kretsloppskontoret, Göteborg, Furuberg K, Norsk Vann, Lindgren P-E, Linköpings Universitet, 

Morrison G M, Chalmers, Myrmel M, Norges Veterinärhögskola, Ottosson J, Statens Veterinärmedicinska anstalt, 

Schultz A C, Danmarks Tekniska Universitet, Sal L S, Nedre Rommerike Vannverk, Simonsson M, Livsmedelsverket. 

Modellering, övervakning och källspårning av mikrobiologiska risker i råvatten 

Sokolova E, Pettersson T J R, Chalmers, Åström J, Tyréns AB, Bergstedt O, Chalmers & Göteborg Vatten, 

Kjellberg I, Göteborg Vatten, Hermansson M, Göteborgs Universitet. 


Nyström P-E, Nordensten C, Livsmedelsverket, Abrahamsson E-M, AKRAB. 

Förändringar i sammansättningen av organiskt kol under dricksvattenproduktion 

Lavonen E, Köhler S J, Sveriges Lantbruksuniversitet, Tranvik L, Uppsala Universitet, 

Gonsior M, Linköpings Universitet, Ansker J, Stockholm Vatten. 

Analys av bakteriestammar i biofilmer i dricksvattennät i södra Sverige 

Lührig K, Persson K M, Lunds Universitet & Sydvatten. 

Canbäck B, Johansson T, Tunlid A, Rådström P, Lunds Universitet, 

Avancerad analys av hålrumsmembran i pilotförsök med UF/koagulering 

Keucken A, VIVAB, Donose B C, The University of Queensland, Persson K M, Sydvatten. 

Praktiska erfarenheter av avhärdning i fluidiserad bädd 

Midlöv E, VA SYD, McCleaf P, Uppsala Vatten och Avfall, Pott B-M, Persson K M, Sydvatten. 

Aqua fingerprint – en metod för att karakterisera löst organiskt material i dricksvatten 

Boe-Hansen R, Krüger, Stedmon C, Arvin E, Danmarks Tekniska Universitet.



Lund V, Anderson-Glenna M, Steffensen I-L, Folkehelsoinstituttet, Skjevrak I, Statoil. 

Identitet och nedbrytbarhet för organiska ämnen från PEX-rör i byggnader 

Arvin E, Albrechtsen H-J, Corfitzen C B, Jelinkóva Z, Lützhøft H-C H, Olsson M E, Ryssel S T, Waul C K, 

Danmarks Tekniska Universitet. 

Inträngning av markföroreningar i distributionsnätet 

Bäckström M, Eklund M, Wikström A-S, Vatten & Miljöbyrån 

Svensk utveckling av material i kontakt med dricksvatten 

Rod O, Swerea KIMAB 

Postrar 

Automated monitoring of fecal contamination of water source 

improves the raw water quality in Gothenburg 

Movig T, Colifast 

Disinfection of fungi in drinking water biofilms 

Pursiainen A, Institutet för hälsa och välfärd (THL) & Kuopio Universitet, 

Wortberg T, University of Duisberg-Essen, Hyvärinen A, Miettinen I T, Institutet för hälsa och välfärd (THL). 

Drinking water reservoirs – problem areas and preventive maintenance 

Mattsson M, Amphi-tech Service 

Effect of strainer pore size distribution on residual particle content 

in lake water for artificial recharge in the Vomb basin 

Persson K M, Pott B-M, Sydvatten, Eckberg C, Hérail E, Since C, Universite de Limoges. 

GenoMembran – removal of natural organic matter from lake water with membrane technology 

Persson K M, Sydvatten 

Investigating drinking water outbreaks and monitoring micribiological raw water quality 

Hallin E, Allestam G, Schönning C, Smittskyddsinstitutet 

Microbial removal of manganese in rapid sand filters 

Lin K. Smets B F, Albrechtsen H J, Danmarks Tekniska Universitet 

Microbiological pollution from small traffic related urban catchments 

Czemiel Berndtsson J, Persson K M, Sydvatten 

On-line modelling and active leakage management 

Høgh K, NIRAS 

Operational use of hydraulic on-line modelling 

Elkjaer L, NIRAS


Satellite data for raw water quality mapping 

Persson K M, Sydvatten, Philipson P, Brockmann Geomatics Sweden AB, Carlsson M, Länsstyrelsen i Jönköpings län, 

Stibe L, Länsstyrelsen i Hallands län, Andersson M, Länsstyrelsen i Kronobergs län. 

Ultrafiltration for detection of bacterial biothreat contaminants in drinking water 

Karlsson L, Totalförsvarets forskningsinstitut (FOI), Hallin E, Schönning C, Smittskyddsinstitutet, 

Lundin-Zumpe A, Ågren P, Lavander M, Livsmedelsverket, Stephansson O, Statens Veterinärmedicinska Anstalt. 

Water disinfection using ultraviolet light emitting diodes 

Rantalankila M, Lappeenranta Universitet

Session 1: Management 

Drick kranvatten – utvärdering och 

handledning av ett kommunikationsprojekt 12 

Implementering av managementsystem 

i vattentjänstföretag 15 

Regional riskbedömning av 

dricksvattenförsörjning 23 

Exempel på och erfarenheter av svenska 

arbetsmetoder för HACCP 31 

Benchmarkingmodell för dricksvatten- 

försörjning i Sverige 36 

11

Drick kranvatten – ett kommunikationsprojekt 

Marie Nordkvist Persson 

Sydvatten AB, Skeppsgatan 19, 211 11 MALMÖ 

Abstract: The largest communication project in drinking water in Sweden has been carried out in the 

owner-municipalities of Sydvatten during three years. The project Drink tap water aims at schools and is 

co-financed by Sydvatten and the 15 owner-municipalities. The aim is to increase knowledge about tap 

water and to raise the status of tap water among the customers in order to get young people to drink more 

tap water. 

In the spring 2012, the project has been evaluated and a tutorial on how knowledge and experiences of 

communication about drinking to teenagers has been developed. The feedback from participating teachers 

and students has been documented and compared with the theories of strategic communications. A 

tutorial on how a corresponding communication project aimed at schools can be implemented targeting 

other players in the water industry has also been developed. 

Kranvatten är hälsosamt, billigt och miljövänligt. Det är det huvudsakliga budskapet i skolprojektet Drick 

kranvatten som riktar sig till elever i årskurs 6-9. Projektets omfattning och karaktär saknar motstycke i 

Sverige. Drick kranvatten drivs av Sydvatten AB, en av landets största dricksvattenproducenter, i 

samarbete med företagets delägarkommuner. Syftet är att informera unga konsumenter om kranvattnets 

många förtjänster. 

På produktens egen webbplats www.drickkranvatten.se finns vattenfakta och färdiga lektionsförslag som 

underlättar för lärarna att lyfta in olika aspekter av vatten i undervisningen. Lektionerna är kopplade till 

kursplanernas centrala innehåll i Lgr11, grundskolans läroplan, för NO, SO med flera ämnen. 

Frågesporter, vattentävlingar och en Facebook-grupp har också lagts till för att stödja initiativet. 

100 skolor och 30 000 elever 

Målet med Drick kranvatten-projektet i sin helhet är att göra kranvatten till en naturlig del av skolans 

miljö- och hälsoarbete. Efter att ha arbetat med Drick kranvatten bör eleverna känna till: 

att tillgång till rent vatten är avgörande för vår hälsa. 

att floder, sjöar och grundvatten är viktiga som dricksvattenkällor. 

att svenskt kranvatten är av mycket hög kvalitet. 

att kranvatten är ett hälsosamt dryckesval. 

att kranvatten är billigt, ca 1 000 gånger billigare än flaskvatten eller läsk. 

att kranvatten är ett bra miljöval. 

Eleverna bör dessutom kunna reflektera över: 

vattenproblematik i världen med ledorden: fördelning, tillgång och brist. 

behovet av friskt vatten i ett globalt perspektiv och vilka följder bristen på rent vatten kan få. 

vatten som orsak till konflikt och samarbete mellan regioner respektive länder. 

Projektet omfattar 100 skolor med sammanlagt cirka 30 000 elever. En projektledare, som är både lärare 

och journalist, har värvats för att introducera Drick kranvatten på skolorna, utveckla det pedagogiska 

materialet samt stödja lärarna under arbetet med tema vatten. 

När eleverna har arbetat med vattentemat får skolan en kranvattenautomat som ger både kylt vanligt 

kranvatten och kolsyrat kranvatten. Alla elever får även sportflaskor med Drick kranvatten-tryck. 

När kranvattenautomaten är installerad arrangerar skolorna invigningsceremonier med underhållning och 

aktiviteter kopplade till kranvattentemat, till exempel sånger, frågesporter, fototävlingar, uppvisningar 

och maskerader. 

På den skola i varje kommun som först kommer med i Drick kranvatten-projektet arrangerar Sydvatten en 

kommunpremiär då en grupp parkour-artister uppträder för skolans elever och personal. 

12 Session 1: Management

För att ytterligare öka intresset för kranvattenautomaterna utrustas vissa av dem med en så kallad 

pratkran. En rörelsesensor startar inspelade vattenbudskap som slumpmässigt spelas upp när någon 

närmar sig för att hämta vatten. 

Samarbete för affärsmässig samhällsnytta 

Sydvatten AB är ett kommunägt företag som producerar dricksvatten till 850 000 invånare i 16 

delägarkommuner i Skåne. Bolaget levererar dricksvattnet till kommungränserna, därefter tar respektive 

kommun över distributionen inom det egna området. 

Då Sydvatten är ett kommunägt aktiebolag är samarbete för affärsmässig samhällssnytta en av 

grundstenarna. Bolaget ska vara konkurrenskraftigt, ta del av utvecklingen inom branschen samt bidra till 

kommunernas utveckling. Samhällsnyttan går före vinstmaximering genom ett mycket långsiktigt 

ansvarstagande för att säkerställa dricksvattenleveranserna till ett rimligt pris. Ett av ägarnas uppdrag till 

bolaget är att skapa ytterligare samhällsnytta genom att kommunicera värdet av kranvatten och lyfta fram 

kranvattnets höga kvalitet. 

Behov och hot 

Till för några år sedan fanns knappast något behov av att sprida information om kranvatten. Sverige har 

mycket vatten av god kvalitet. Tjänsterna för att leverera vatten och ta hand om avloppsvatten är 

offentligt ägda. De finansieras genom taxor, enligt självkostnadsprincipen, och får inte generera vinst. De 

flesta framtidsfrågor som diskuterades inom branschen rörde teknik och produktion, till exempel 

klimatförändringars inverkan på försörjningstryggheten. 

Men saker har förändrats. Produkten kranvatten började under 1990-talets slut att utsättas för nya typer av 

hot och konkurrens: 

Kommersiella intressen, bryggerinäringen, producerar bordsvatten som beskrivs såsom 

hälsosammare och renare än kranvatten. 

Livsstilsprogram uppmanar folk att köpa och dricka vatten på flaska. 

Restauranger serverar kranvatten som har filtrerats lokalt och påstås vara renare och smaka 

bättre än vanligt kranvatten. 

Debatter om medicinska och kemiska rester i kranvatten riskerar att skapa osäkerhet hos 

allmänheten. 

Med hänsyn till ovanstående gjordes på Sydvatten bedömningen att det förelåg ett uppenbart 

informationsbehov om kranvatten som en nyttig, billig och klimatsmart dryck. 

Mål och målgrupper 

Målsättningen med Drick kranvatten är att öka medvetenheten om kranvattnets värde, att stärka 

kranvattnets varumärke och att bibehålla tilliten till och förtroendet för vårt dricksvatten. Valet av 

målgrupp är grundskoleelever i åldrarna 13–16 år och baseras på: 

att ungdomar i denna ålder är stora läskkonsumenter. 

att många tonåringar börjar reflektera över kropp, diet och sportaktiviteter på ett nytt sätt. 

att unga människor behöver uppmuntras att tänka på hur deras val av dryck påverkar hälsa, 

ekonomi och miljö. 

att ungdomar har egna pengar, gör egna inköp och skapar sina egna vanor. 

att ungdomar har avsevärt inflytande över sina familjers inköpsvanor. 

Ett kommunalt samarbete 

Inom bolaget finns sedan länge tre plattformar för samarbete mellan delägarna. På dessa plattformar möts 

representanter från teknik-, finans- och kommunikationsavdelningarna regelbundet och håller sig 

uppdaterade om utvecklingen inom dricksvattensektorn. Drick kranvatten-projektet har förberetts av 

kommunikationsgruppen. Projektet är ett samarbete mellan Sydvatten och delägarkommunernas VAorganisationer. 

Den totala budgeten för projektet är omkring 5 miljoner kronor – hälften av beloppet 

kommer från bolaget och hälften från delägarkommunerna. 

Session 1: Management 13

Preliminära slutsatser 

Drick kranvatten utvärderas regelbundet genom att lärare och elever besvarar enkäter. Enkätsvaren visar 

på positiva resultat av projektet. 78 % av eleverna svarar att de under skoltid väljer att dricka kranvatten 

istället för annan dryck efter att ha arbetat med Drick kranvatten. 52 % anger att de dricker mer 

kranvatten under skoltid jämfört med tidigare. 28 % anger att de dricker mer kranvatten även på fritiden. 

Drygt 70 % menar att de har fått ökad förståelse för hur viktigt vatten är för hälsa och miljö. 70 % anser 

att de har fått ökad förståelse för vad vatten kostar jämfört med andra drycker. 

Lärarnas enkätsvar tyder på att webbplatsen är ett användbart pedagogiskt redskap. En lärare beskriver 

den så här: ”En enorm samling mycket bra information som man kan använda för elevernas skull. Den 

sparade tid, och gav mig nya idéer.” 

Det allmänna stödet från lärarna är överväldigande. 97 % av lärarna säger att de har haft nytta av 

lektionsförslagen och att de har besparat dem förberedelsetid. 99 % av lärarna är positiva till Drick 

kranvatten och projektets resultat på den egna skolan. 

Under 2012 genomför Institutionen för strategisk kommunikation vid Lunds Universitet, Campus 

Helsingborg, en utvärdering av elev- och lärarenkäterna. Den kvantitativa analysen har kompletterats med 

en kvalitativ undersökning i form av intervjuer med lärare och elever i ett antal skånska skolor. 

Utvärderingen, samt en handledning för att genomföra ett motsvarande kommunikationsprojekt av andra 

aktörer inom VA-branschen, kommer att redovisas under hösten 2012. Utvärderingen/handledningen 

finansieras av Sydvatten tillsammans med medel från Svenskt Vatten Utveckling och kommer att 

publiceras som SVU-rapport. 

Handledningen utgår från konkreta erfarenheter och praktiska tips. Drick kranvatten har genomförts i tre 

steg: förankring i kommunerna, introduktion på skolorna och genomförande på skolorna. 

Introduktionen har sett olika ut beroende på kommun och kommunstorlek. I mindre kommuner har 

projektledaren vanligen fått möjlighet att presentera Drick kranvatten på ett möte med alla rektorer. I 

vissa fall har projektledaren uppmanats av skolchefen att ta kontakt med respektive rektorer direkt. I stora 

kommuner, med mer än en skolförvaltning eller motsvarande organisation, har det krävts fler möten både 

horisontellt och vertikalt i kommunorganisationen. Målet har varit att även i de stora kommunerna få 

tillgång till skolchefernas/stadsdelarnas rektorsmöten. 

Underlätta och spara tid är nyckelord för att skolorna ska utnyttja erbjudandet om att ansluta sig till Drick 

kranvatten. Projektet ska ses som ett intressant erbjudande till skolorna och ett användbart hjälpmedel i 

den pedagogiska verksamheten. 

Det verkar inte finnas någon idealisk tidpunkt för att presentera ett projekt i skolorna. Skolpersonalen har 

alltid mycket att göra med planering inför en ny termin, avslut före ett lov, utvecklingssamtal, nationella 

prov, betygsättning, oväntade situationer som har uppstått osv. Vi har provat många olika tidpunkter. Det 

har fungerat något bättre om vi har nått rektorer och lärare väldigt tidigt på terminen eller helst innan 

terminen har startat, under personalens studiedagar. 

Rektorerna har sällan tid att ägna sig åt Drick kranvatten och för vår del är det viktigare att få 

direktkontakt med den eller de lärare som ska arbeta med projektet. Bäst har projektet fungerat på de 

skolor där vi har etablerat en positiv kontakt med en engagerad lärare. Kopplingen till kursplanernas 

centrala innehåll betonas vid introduktionen för att projektet nyttovärde ska framgå tydligt för lärarna. 

Vårt pedagogiska material ska ses som en hjälp till lärarna. Det är också viktigt att framhålla att lärarna 

inte behöver redovisa vad de gör i projektet, om de inte själva vill det genom att till exempel ladda upp 

eget material på hemsidan. 

De preliminära resultaten tyder på att fördjupad kunskap och förståelse för vattenfrågor bäst uppnås 

genom tematiskt och ämnesövergripande arbete på skolorna. Elever med en initialt positiv inställning till 

kranvatten tenderar att förstärkas i sin uppfattning genom Drick kranvatten-projektet. 

Vi konstaterar att ett kommunikationsprojekt kan påverka vanor och dryckesbeteenden. Vi är dock 

medvetna om att det är svårt att uppnå bestående förändringar i attityder och beteenden. För att lyckas är 

det avgörande att fortsätta bygga kunskap och förtroende hos målgruppen, i detta fall lärare och elever. 


Implementation of Management Systems in Water and Sewerage 

Utility Companies 

*Christian Rosen Balder, **Thomas Haurdahl, ***Stefan Schmidt 

* NIRAS, Sortemosevej 19, 3450 Allerød, crb@niras.dk, ** NIRAS, Sortemosevej 19, 3450 Allerød, 

tho@niras.dk, *** NIRAS, Åboulevarden 80, Postboks 615, 8100 Århus C, sts@niras.dk 

Abstract. The Danish branch of municipality owned water and sewerage companies has undergone major 

changes the last few years. From being an integrated part of the municipal organisation they have been 

separated from the municipality and turned into independent utility companies. At the same time there has 

been a major reconstruction of Danish municipalities going from 270 to less than 100. As a result hereof 

these newly started companies need to establish their own way of management. In this article we describe 

how to implement management systems successfully (ISO 14001, ISO 22000, ISO 9001, and OHSAS 

18001) in order to change the company culture from reactive to proactive. Experiences documented in this 

article are based upon project results from Danish utility companies: 

1. Guldborgsund: Implementation of Risk Management System in Water Supply 

2. Vordingborg: Implementation of Management Report in Multi Utility Company 

3. Hjørring: Strategic Development Plan for Assets in Water Supply 

4. Esbjerg: Implementation of Management Information System 

5. Energiforsyning Køge: Risk Management at Waste Water Treatment Plant 

and results from an interview study conducted in 2011 by NIRAS among 25 Managing Directors of larger 

utility companies in Denmark. 

Vand og afløbsselskaber - en ny industri 

Den danske forsyningssektor har undergået store forandringer. Der er på få år gennemført en 

kommunalreform, hvor antallet af kommuner er reduceret fra ca. 270 til ca. 100 og efterfølgende er den 

kommunale drift af vand- og afløbsaktiviteter udskilt i selvstændige selskaber. Med introduktionen af 

selvstændige selskaber og flere forsyningsgrene under samme selskab er kravene til ledelsen og deres 

systemer blevet ændret. Derfor er der skabt behov for et mere dedikeret fokus på selskabets forpligtelser i 

forhold til kunder, myndigheder og samfund. Det betyder et skifte i holdninger og driftsfilosofi. Hvor 

man tidligere så udgifter som hovedfokusområde, må man nu også se på områder som interessenternes 

krav og forventninger samt selskabets behov for udvikling af kompetencer. I januar 2012 gennemførte 

NIRAS en interviewundersøgelse med deltagelse af 25 direktører fra nyetablerede kommunalt ejede 

forsyningsselskaber. Analysen viste en klar tendens til, at ledelserne i de danske vand- og afløbsselskaber 

er indstillet på at gennemføre en markant udvikling af selskabernes effektivitet, økonomistyring, miljø og 

forsyningssikkerhed (inkl. drikkevandskvalitet). Reformen i vand- og afløbsselskaberne har med andre 

ord dannet grundlag for, at der er skabt en ny industri i Danmark. 

Dette skifte betyder, at vi i stigende omfang ser forsyningsselskaber implementere ledelsessystemer, som 

i dag er gængse inden for de traditionelle industriområder. 

Forudsætninger for succes med ledelsessystemer 

Det er vores erfaring, at forsyningsselskaberne må gå fra et reaktivt ledelsessyn til et proaktivt og 

forudsigende ledelsessyn, se figur 1. Populært sagt må man væk fra holdningen, at planlægning og 

forebyggelse ikke kan betale sig og man må tro på, at der er et forbedringspotentiale, som kan indfris 

gennem løbende forbedringer. Det reaktive ledelsessyn kommer bl.a. til udtryk, når man bevidst fravælger 

forebyggende vedligehold. Det kan forsvares, hvis man alene ser det ud fra et rent driftsøkonomisk 

synspunkt. Det er bare ikke driftssikkert, det er ikke miljøvenligt, og det er ikke udviklende for selskabet. 


Investeringer i ledelsessystemer handler derfor om mere end driftsøkonomi, det handler om at opnå et 

mere sikkert og miljøvenligt vand- og afløbsselskab. 

Ledelsessystemer er ikke et mål i sig selv. Der er nogle, som fejlagtigt betragter et ISO certifikat som et 

mål i sig selv. Ledelsessystemet er et middel/værktøj, der hjælper selskabet til at nå ønskede mål. 

Vellykket implementering af ledelsessystemer i forsyningsselskaber starter med ledelsens udtrykte ønske 

om at ville forbedre selskabets resultater gennem forebyggelse og gennem løbende forbedringer. Ledelsen 

skal ville det så meget, at de ikke kan lade være med at efterspørge (ofte kaldet: Træk på engelsk: Pull), at 

der er styr på tingene. Dvs. de efterspørger, at arbejdsopgaver planlægges, resultaterne evalueres og 

indsatserne løbende forbedres med udgangspunkt i beslutninger baseret på fakta. 

Figur 1: Holdnings- og kompetenceskifte ved indførelse af ledelsessystemer 

Vision, mission og værdier 

Fastsættelse og kommunikation af vision, mission og værdier danner et grundlag, hvor der bakkes op om 

de aktiviteter, der udgør ledelsessystemet. I visionen formuleres den idealsituation, som ledelsessystemet 

skal hjælpe med til at opnå, fx: Vi vil levere drikkevand af høj kvalitet, effektivt og til rimelige priser med 

respekt for miljøet. 

I missionen fastsættes den grundpræmis, som skal være til stede for, at visionen kan opnås, fx: Det er os, 

der styrer anlæggene - ikke anlæggene, der styrer os. 

Formulering af værdierne kan hjælpe med til at fremme nye holdninger og adfærd hos medarbejderne. 

Det kan fx handle om samarbejde (åbenhed, ærlighed, loyalitet, fællesskab), hvordan man arbejder (efter 

planer, standardiseret, gør tingene rigtigt første gang/effektivt, disciplineret osv.). 

Når selskaber ønsker at opnå endnu bedre resultater, ønsker de samtidigt forandringer i medarbejdernes 

værdier, holdning og adfærd. Det er i dette lys, at vision, mission og værdier kan anvendes som 

argumentation for en ønsket forandring. Med vision, mission og værdier har ledergruppen en ensartet, 

gennembearbejdet, og (forhåbentlig) overbevisende argumentation, når de skal svare på spørgsmål som: 

Hvorfor skal vi bruge ekstra tid til at planlægge, vi har jo travlt nok i forvejen? Svar: (vision) Det er 

fordi, vi gerne vil levere drikkevand af høj kvalitet. (mission) Det kan vi kun gøre, hvis det er os, der 

styrer anlæggene og ikke anlæggene, der styrer os. (værdier) For at vi kan styre anlæggene, skal vi 

samarbejde, være åbne osv. osv. 

Ledelsessystemer (ISO 9001/14001/22000 og OHSAS 18001) bygger på otte fælles principper, som 

udtrykker den grundindstilling, der ligger bag. De er gode at sætte sig ind i, når man skal arbejde med 

ledelsessystemer. 

1. Kundefokus 


Virksomheder er afhængige af deres kunder, og de bør derfor forstå nuværende og fremtidige kundebehov, 

opfylde kundekrav og stræbe efter at overgå kundernes forventninger 

2. Lederskab 

Ledere skaber en helhed af formål og udviklingsretning for virksomheden. De bør skabe og opretholde et internt 

miljø i virksomheden, hvori medarbejderne kan blive fuldt involveret i at nå virksomhedens mål 

3. Involvering af medarbejdere 

Medarbejdere på alle niveauer er det væsentlige i en virksomhed, og deres fulde involvering gør det muligt, at 

deres evner anvendes til gavn for virksomheden 

4. Procesorientering 

Et ønsket resultat opnås mere effektivt (ressourcerelateret), når aktiviteter og tilhørende ressourcer styres som en 

proces 

5. Systemorienteret ledelse 

At identificere, forstå og styre indbyrdes relaterede processer så et system bidrager til virksomhedens effektivitet 

(resultatrelateret og ressourcerelateret) med hensyn til at nå dens mål 

6. Løbende forbedringer 

Ledere skaber en helhed af formål og udviklingsretning for virksomheden. De bør skabe og opretholde et internt 

miljø i virksomheden, hvori medarbejderne kan blive fuldt involveret i at nå virksomhedens mål 

7. Faktuel beslutningstagning 

Effektive beslutninger er baseret på analyse af data og informationer 

8. Gensidige fordelagtige leverandørrelationer 

En virksomhed og dens leverandører er afhængige af hinanden, og en gensidig fordelagtig relation øger begge 

parters værdiskabende evne 

Mål 

••For den, der ikke ved hvilken havn han styrer imod, er ingen vind gunstig•• Seneca, romersk filosof. Det 

er et fåtal af de danske vand- og afløbsselskaber, der aktivt anvender målstyring som ledelsesværkstøj til 

forcering af udviklingen af selskabets resultater. Balanced Scorecard modellen er et godt udgangspunkt 

for identifikation af relevante mål, se figur 2. 

Figur 2: Eksempel på Balanced Scorecard modellen anvendt til udpegning af mål i vand- og afløbsselskab 

Indførelse af målstyring er ofte en krævende proces. Arbejdet med at indføre målstyring handler mere om 

at ændre vaner end om at indsamle og behandle data. Målstyring omfatter: Fastsættelse af mål 

(talbestemte, tidsbestemte), indsamling af data og beregning af nøgletal (fx på uge og månedsbasis) samt 

analyse og evaluering af resultater i forhold til opstillede mål. I figur 3 er givet et eksempel på, hvordan 

data der indsamles kan visualiseres og danne grundlag for en månedlig management rapport. 


Figur 3: Eksempel på visualisering af resultater i månedlig managementrapport i vand- og afløbsselskab. 

Strategi 

Med strategi skal her forstås ••plan for at nå langsigtede mål••. Strategier hjælper selskaberne med at 

udvælge anlægs- og forbedringsprojekter, som både løser aktuelle udfordringer og samtidigt tager højde 

for udfordringer, der forventes på lang sigt, fx klimapåvirkninger, ændrede udledningskrav, ændringer i 

befolkningsgrundlag osv. Ser vi på anlægsstrategien, så indeholder den svarene på spørgsmål som: 

Hvilken anlægsstruktur vil være den bedste i vores forsyningsområde de kommende 1- 5 år, om 20 eller 

80 år med de forventninger, vi har til fremtiden. Ser vi på forbedringsstrategien, så giver den svarene på, 

hvordan selskabet bedst muligt og mest hensigtsmæssigt kan organisere arbejdet med løbende 

forbedringer og hvilke metoder, der kan anvendes. 

Udarbejdelse af en anlægsstrategi er en kompleks opgave. Vores erfaringer er, at det er en hjælp at opdele 

arbejdet i fire faser. I første fase fastsættes de langsigtede mål for forsyningens anlæg (de skal være 

bæredygtige, miljøvenlige, effektive osv.), datakilder identificeres og arbejdet organiseres. I fase to 

udpeges de funktioner og områder i anlæggene, som på kort og lang sigt vurderes at være kritiske i 

forhold til de opstillede mål. Her ser man på anlæggenes kapacitet, alder, pålidelighed og driftsøkonomi. 

Man vurderer de fremtidige grundvandsressourcer, recipienter, udvikling i befolkningsgrundlag og 

forventninger til klimapåvirkningers eventuelle betydninger. I tredje fase kan man opstille mulige 

scenarier for udviklingen inden for nogle af de parametre, der kan blive kritiske, herunder alternative 

løsningsmodeller for den fremtidige anlægsstruktur, anvendelsen af forskellige grader af automation i 

styring og overvågning, in- eller outsourcing af arbejdsopgaver samt de økonomiske konsekvenser. I 

fjerde fase udarbejdes strategiplanen, så aktiviteter på kort og lang sigt er beskrevet, og der er udarbejdet 

en investeringsplan og en plan for fremtidige takster og cashflow. 


Figur 4: Proces til udarbejdelse af anlægsstrategi i vand- og afløbsselskab 

Udarbejdelse af en forbedringsstrategi kan hjælpe selskabet til at italesætte, organisere og iværksætte en 

effektiv forbedringsindsats, hvor der skabes en synergi mellem selskabets forskellige funktioner. Synergi 

kan skabes i et vand og afløbsselskab ved at se på, hvordan selskabets forskellige funktioner bidrager til 

selskabets samlede performance. Det gør de fx, når man i teknik og anlægsafdelingen sørger for, at 

anlæggene og processerne er stabile og pålidelige ••dvs. de er ikke for gamle og kapaciteten passer ••så 

giver man drift- og vedligeholdsfunktionen de bedste vilkår for at kunne gennemføre forebyggende 

arbejder og være beredt til hurtig udrykning i tilfælde af havari eller anden form for fejl. I figur 5 er denne 

sammenhæng illustreret. Synergien ses ved den accelererede forbedring af performance. Der vil være 

flere sammenhænge, som giver synergi. Når synergien er indset, handler det om at finde ud af, hvilke 

metoder man kan benytte til at forbedre sig efter. Det er vores erfaringer, at følgende tre tilgange er 

anvendelige i vand- og afløbsselskaber: 

1. I de ISO baserede ledelsessystemer bygger forbedringer på, at man dels arbejder med en 

handlingsplan (fx som beskrevet ovenfor med anlægsstrategien) og dels ved identifikation af 

afvigelser, årsagsanalyse og gennemførelse af korrigerende handlinger (til fjernelse af årsager) 

2. LEAN de fleste forbedringsmetoder fra LEAN kan anvendes. Eksempelvis: 5S kan hjælpe med til at 

skabe orden og ryddelighed på værksted, i biler og på kontorer, værdistrømsanalyse kan anvendes til 

forbedring af beredskab (fx ved ledningsbrud) 

3. Pålidelighed og six sigma ••her anvendes statistik som grundlag ( fx vedr. brud, fejl og 

procesvariation) til fastsættelse af optimale levetider, serviceintervaller og reduktion af 

procesvariation (fx fra beluftning og filtrering af drikkevand eller fra rensning af spildevand) 

Figur 5: Sammenhænge mellem forskellige indsatser og performance i vand- og afløbsselskab 

Opbygning af ledelsessystem 

ISO-ledelsessystemer (herunder kvalitet, miljø, fødevaresikkerhed og arbejdsmiljø) har alle et fælles 

udgangspunkt, idet de: 


Identificerer risici, sætter prioriteter og etablerer dynamiske programmer og planer, der 

omkostningseffektivt skaber forbedringer 

Udviklingen går i retning af, at man i stigende omfang benytter risikostyring som udgangspunktet for 

ledelsessystemer. Vores erfaringer i vand- og afløbsselskaber viser, at det giver enklere og mere 

værdiskabende systemer. Enklere, fordi man benytter samme ordvalg, uafhængigt af om man taler om 

service, kvalitet, arbejdsmiljø eller miljø. Mere værdiskabende, fordi man opnår en mere klar og 

pædagogisk let forståelig sammenhæng mellem risici (de forhold, der har med værdi at gøre) og indsatser 

(fx rutiner, instruktioner, måling og registrering). Det har de fordele, at man sætter fokus på de 

værdiskabende ting, det er ikke svært at gøre det sammen med medarbejderne og det kræver ikke særlig 

megen dokumentation. I figur 6 er princippet for opbygning af ledelsessystemet vist. Her fremgår 

sammenhængene mellem den værdiskabende proces og de forskellige elementer i ledelsessystemet. 

Figur 6 Principper for opbygning af et ledelsessystem, her eksemplificeret med kloaker og renseanlæg 

Ud over de aktiviteter, der er skitseret i figur 6, stiller ISO systemerne krav til, at selskabet har beskrevet 

politiker (kvalitet, miljø, sikkerhed), fastsat mål, fastsat ansvar og beføjelser samt procedurer for træning, 

uddannelse og kompetencer, dokument- og datastyring, intern audit og korrigerende handlinger. Der er 

mindre forskelle mellem standarderne, men de overordnede principper er ens. 

Ledelsessystemerne er målrettet forskellige områder. Kvalitet er orienteret mod kunderettede processer, 

miljø handler om ressourcer (energi, vand og materialer), forurening (jord, luft, vand, støj og gener), 


drikkevandskvalitet handler om kemiske, bakteriologisk og fysiske forureninger af drikkevand. I tabel 1 

har vi givet eksempler på typiske processer, aktiviteter og hændelser. 

Tabel 1: Eksempler på processer, aktiviteter og hændelser der kan indgå i ledelsessystemer i vand og 

afløbsselskaber 

Typiske processer/aktiviteter/hændelser i vand- og afløbsselskaber Ledelsessystem 

Kunderettede processer: 

Produktinformation, vandregulativ, indgåelse af aftaler, tilkobling, installation, 

måleraflæsning, forbrugsafregning, tømningsordning, indkøb, lagerstyring 

Miljøforhold: 

Vandindvinding, elforbrug til pumper, beluftere m.v., udledning af skyllevand, 

håndtering af farlige stoffer og materialer, håndtering af affald, styring og 

overvågning af processer, overholdelse af vilkår i spildeandstilladelser fra 

renseanlæg og overløbsbygværker, vedligehold af pumpestationer og 

rensningsanlæg, brand og eksplosion 

Drikkevandssikkerhed: 

Analyse af grundvandskvalitet, boringskontrol, brud på vandledninger, hygiejne 

ved arbejde med vandbehandlingsanlæg, tilsyn, kontrol og vedligehold af 

vandbehandlingsanlæg, anvendelse af godkendte materialer og komponenter, 

tilsyn med entreprenører ved ledningsarbejder, kontrol med installationer hos 

kunder, håndtering af vandforurening 

Arbejdsmiljø: 

El-sikkerhed, håndtering af kemi, kloakarbejde, tunge løft, vibrationer, ergonomi, 

løfteudstyr, ulykkesrisici med stiger, taljer, seler, ATEX krav i forbindelse med 

rådnetanke og gas, vaccinationer, førstehjælp 

ISO 9001, kvalitetsledelse 

ISO 14001, miljøledelse 

ISO 22000, fødevaresikkerhed 

OHSAS 18001, 

arbejdsmiljøledelse 

Selskaber, der indfører mere end et ledelsessystem, vil med fordel kunne have fælles procedurer vedr. fx 

dokument- og datastyring, afvigelser og korrigerende handlinger, så systemerne så vidt muligt integreres. 

Implementering 

Udfordringen er ikke at udarbejde et ledelsessystem men at skabe bedre resultater ved at få 

organisationen til at arbejde systematisk i henhold til systemet. Denne erkendelse bør anvendes som 

grundlag for implementeringen. Det er vores erfaring, at de metoder, der anvendes i driften af vand- og 

afløbsselskaber, er baseret på en lang tradition. Mange af selskaberne har eksisteret i mere end 100 år, så 

erfaring i, hvordan man driver et vand- og afløbsselskab, er der som regel rigeligt af. Det, som er nyt, er 

involveringen af alle medarbejderne i at arbejde forebyggende og sikkert samt i at evaluere indsatser og 

resultater. Det kræver fælles billeder og forståelse af, hvad der vigtigt og, hvorfor det er vigtigt. Vores 

erfaringer med implementering af ledelsessystemer i vand- og afløbssystemer kan opsummeres til: 

Aktiviteter med udvikling og implementering bør gennemføres i teams med 5-12 deltagere (alle 

medarbejderne i selskabet bør principielt deltage i processen) 

Aktiviteterne bør ikke vare mere end 2,5 time ad gangen (så mistes koncentrationen) 

Kortlægning bør altid suppleres med konkrete anlægsbesøg (så er der mulighed for at konkretisere 

principperne) 

Dokumentation af selskabets driftsstyring bør tage udgangspunkt i den praksis, der er, og ikke forsøge 

at revolutionere praksis 

Dokumentationen skal være minimalistisk, dvs. hvad, hvornår og hvem ••ikke hvordan, med mindre 

det er strengt nødvendigt 

De mangler, der evt. identificeres ved kortlægning af den nuværende praksis, bør indgå i en prioriteret 

handlingsplan, hvor man gennemfører forbedringerne i en takt, der er realistisk i forhold til selskabets 

ressourcer og øvrige planlagte aktiviteter 


Der bør gennemføres et træningsforløb for selskabets teams i ressourceplanlægning, evaluering af 

indsatser og resultater samt gennemførelse af løbende forbedringer 

Træningsforløbet kan gennemføres over en tre-måneders periode, hvor teams lærer at benytte 

teknikkerne på ugemøder 

Ledergruppen er også et team og bør også deltage i træningsforløb 

Implementering af et ledelsessystem tager fra 6-12 måneder afhængigt af selskabets kompleksitet og 

størrelse, tiden er ikke det afgørende 

Man bør altid afgrænse sit ledelsessystem og ikke forsøge at tage alle typer risici med i en omgang, fx 

alene fokusere på drikkevandskvalitet, eller miljø. 

Referencer 

Balder C.R. m.fl. (2012). Analyse af forsyningssektoren, Rapport kan rekvireres hos NIRAS (crb@niras.dk) 

EN ISO 9000, 2000, Quality Management Systems ••Fundamentals and vocabulary 

DS/EN ISO 9001, Kvalitetsledelsessystemer ••Krav, 4. udgave, 2008-12-09 

DS/EN ISO 14001, Miljøledelsessystemer ••Krav med anbefalinger om anvendelse, 2. udgave, 2004-11-30 

DS/OHSAS 18001, Arbejdsmiljøledelsessystemer ••Kravbeskrivelse, 2. udgave, 2008-01-14 

DS/EN ISO 22000, Ledelsessystemer for fødevaresikkerhed ••Krav til virksomheder i fødevarekæden, 1. udgave, 

2005-12-22 

Robert S. Kaplan og David P. Norton: The Balanced Scorecard ••Measures that Drive Performance, Harvard 

Business Review , January-February 1992. 


Regional risk- och sårbarhetsanalys för dricksvattenförsörjning 

Andreas Lindhe*, Olof Bergstedt* / **, Lars Rosén*, Thomas J.R. Pettersson*, 

Christina Nordensten*** 

* Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 

Gothenburg, andreas.lindhe@chalmers.se, lars.rosen@chalmers.se, thomas.pettersson@chalmers.se 

** Göteborg Vatten, Box 123, SE-424 23 Angered, Sweden, olof.bergstedt@vatten.goteborg.se 

*** The National Food Agency, Box 622, SE-751 56 Uppsala, Sweden, christina.nordensten@slv.se 

Abstract. Water utilities have to manage a wide range of risks to guarantee the consumers a safe and 

reliable supply of drinking water. Current risks and emerging risks due to e.g. climate changes call for 

different measures that may have local but also regional effects. The drinking water supply in one 

municipality may be dependent on the supply system in one or several other municipalities. For example, 

municipalities may share the same raw water source and the distribution systems may be interconnected 

so that water can be transferred between municipalities. It is thus important to assess risks on a regional 

level. Such assessments facilitate analyses of effects due to e.g. centralisation where several smaller 

water sources are replaced by one larger water source and/or the distribution systems in adjacent 

municipalities are interconnected to increase redundancy. The World Health Organization emphasises the 

use of water safety plans, which implies a risk-based and integrated approach considering the entire 

supply system, form source to tap. This approach may be further extended to not only consider one supply 

system but an entire region including several systems in different municipalities. In this paper, an approach 

and a set of tools are presented that enable regional risk assessment of drinking water supplies. By 

combining different risk assessment tools, water quality aspects as well as supply interruptions and the 

access to reserve water supplies are considered. The overall approach and the tools are applied in a case 

study including thirteen municipalities in the western part of Sweden. The efficiency of the microbial 

barriers was analysed for each treatment plant and compared to required treatment levels defined by the 

raw water quality. System reliability related to supply interruptions was analysed using a logic model 

considering possible failure events and interconnections between supply systems. The case study results 

show that the approach can be applied to identify and quantify risks affecting smaller as well as larger pats 

of the analysed region. The risks levels are expressed in the same way for all parts of the region which 

enables a simple comparison of how potential risk-reduction measures affect different parts of the 

analysed region. The presented approach and the tools for regional risk assessment facilitate long term 

planning of water supplies including decisions on risk reduction and contingency planning. 

Inledning 

För att uppnå och bibehålla en säker dricksvattenförsörjning krävs ett kontinuerligt arbete med såväl 

daglig drift som långsiktig planering. Ett viktigt underlag för detta arbete är analyser av de risker och 

sårbarheter som finns. Förutom att analysera vattenförsörjningen i enskilda kommuner är det viktig att 

också undersöka beroendet mellan kommunernas system. För att belysa dessa aspekter och visa hur 

regionala analyser kan ge viktigt beslutsstöd genomförs projektet Regional risk- och sårbarhetsanalys för 

centraliserad dricksvattenförsörjning i samarbete mellan Livsmedelsverket, Chalmers tekniska högskola 

och 13 fallstudiekommuner i Västsverige (Ale, Alingsås, Göteborg, Härryda, Kungsbacka, Kungälv, 

Lerum, Lilla Edet, Mölndal, Partille, Stenungsund, Tjörn och Öckerö). I denna artikel beskrivs ett 

arbetssätt för regional risk- och sårbarhetsanalys och dess tillämpning exemplifieras. 

Problembakgrund 

De risker dricksvattenförsörjningen är utsatt för kan orsaka konsekvenser lokalt i en kommun, men även 

regionalt i flera kommuner. Den risk ett vattenförsörjningssystem är utsatt för beror bl.a. på yttre 

förutsättningar, det egna systemet status och funktion samt eventuella beroenden mellan olika kommuner. 

Beroenden kan t.ex. innebära att ledningsnäten är sammankopplade eller att samma vattentäkt utnyttjas. 


En kommun kan ha uteslutande egen vattenproduktion, försörja både sig själva och andra, komplettera 

den egna produktionen med försörjning från en eller flera andra eller försörjas helt från andra. I de fall det 

finns sammankopplingar mellan olika kommuner kan syftet vara att komplettera eller helt ersätta den 

egna produktionen, alternativt att få en reservförsörjning om något skulle inträffa. Orsaken till behovet av 

en sammankoppling kan t.ex. vara brist på råvatten, begränsad produktionskapacitet eller otillräckliga 

barriärer. I Figur 1 illustreras fyra exempel på sammankopplingar för sex kommuner. De olika 

sammankopplingarna har olika styrkor och svagheter, och det går inte att säga vad som är den bästa 

lösningen eftersom förutsättningarna skiljer sig åt. En generell tolkning är dock att sammankopplingar 

kan öka redundansen, men sårbarheten kan bli stor om systemet bygger på att alla sammankopplingar 

måste fungera och om fel kan fortplanta sig. Ett omfattande utbyte av vatten mellan olika kommuner kan 

också påverka spridningen av smittämnen och spårbarheten i händelse av ett vattenburet sjukdomsutbrott. 

Regionala analyser är således viktiga för att belysa både möjligheter och begränsningar. 

Inga sammankopplingar Vissa sammankopplingar Central vattenproducent Omfattande 

sammankopplingar 

Figur 1 Illustration av fyra sammankopplingstyper mellan sex kommuner (cirklarna motsvarar 

kommunerna och pilarna visar hur vattnet överföras mellan kommunerna). 

Behovet av att identifiera, analysera och i stort hantera risker framhålls av många inom 

dricksvattenområdet (CDW/CCME, 2004; IWA, 2004; NHMRC/NRMMC, 2004). 

Världshälsoorganisationen betonar vikten av ett riskbaserat angreppssätt där hela dricksvattensystemet 

beaktas, från råvatten till tappkran (WHO, 2011). Som en del av detta angreppssätt föreslås framtagandet 

av så kallade vattensäkerhetsplaner (water safety plans), vilka bygger på att risker identifieras och 

analyseras. Detta angreppssätt kan utvidgas till att inte bara innefatta vattenförsörjningen i en kommun 

utan en hel region med flera kommuner. För att underlätta genomförandet av regionala risk- och 

sårbarhetsanalyser inom dricksvattenbranschen krävs det dock lämpliga angreppssätt och verktyg. Det 

finns verktyg för att analysera olika dricksvattenrisker men ett regionalt angreppssätt och en anpassning 

av verktygen till det regionala perspektivet saknas. Behovet av ytterligare utveckling och vägledning 

belyses av den utvärdering Riksrevisionen (2008) presenterat, i vilken det konstateras att det finns 

svagheter i de risk- och sårbarhetsanalyser som genomförs inom svensk dricksvattenförsörjning och hur 

de används för att stärka krisberedskapen. 

Resultaten från en regional risk- och sårbarhetsanalys syftar till att beskriva möjligheter och 

begränsningar och utgöra ett beslutsstöd för prioritering av riskreducerande åtgärder och liknande. 

Analysen är således ett underlag för VA-planeringen både lokalt och regionalt. 

Syfte 

Det övergripande syftet med det projekt som ligger till grund för denna artikel är att visa hur regional 

risk- och sårbarhetsanalys för dricksvattenförsörjning kan genomföras. Resultaten från projektet kommer 

att presenteras i en vägledning med bl.a. en omfattande fallstudiebeskrivning. Syftet med denna artikel är 

att principiellt beskriva det arbetssätt som föreslås, de ingående verktygen samt illustrera vilken typ av 

resultat som erhålls och hur denna information kan användas som beslutsstöd. 


Exempel på händelse av regional betydelse 

Den kalla vintern 2009/2010 medförde att vattenförsörjningen i Göteborgsregionen var ansträngd. 

Händelsen kunde inneburit allvarliga konsekvenser och visar att beroendet mellan kommuner kan vara av 

stor betydelse. I Göteborg finns två vattenverk som, utöver den egna kommunen, även förser fyra andra 

kommuner (Ale, Mölndal, Partille och Öckerö) med vatten i olika omfattning. Ale köper lite drygt hälften 

av sitt vatten från Göteborg och resterande del från Kungälv. Mölndal och Partille har egna vattenverk, 

men kompletterar produktionen med vatten från Göteborg. Öckerö köper allt sitt vatten från Göteborg. 

Vintern 2009/2010 var antalet rörbrott betydlig högre än normalt i många kommuner. Den låga 

vattentemperaturen begränsade maxproduktionen på vattenverken, vilket är normalt, genom att längre 

uppehållstider krävs i avskiljningsstegen för att upprätthålla den mikrobiologiska barriärverkan. I 

Göteborg upptäcktes cirka 100 rörbrott under januari och februari. Åtgärder vidtogs men läckaget ökade 

markant och dricksvattenbehovet var därför 20 % högre än normalt. En skada uppstod på en av två 

matningar från ett av vattenverken samtidigt som maxproduktionen var begränsad till följd av den låga 

temperaturen. Detta medförde åtta dygns balansgång mellan omfattande leveransavbrott och 

kokrekommendation för en halv miljon människor. Samtidigt uppstod en vattenbrist och periodvis 

leveransavbrott i Partille kommun till följd av bl.a. ett svåridentifierat rörbrott. Detta kunde ha påverkat 

möjligheten till nödvattenförsörjning till ett akutsjukhus, som normalt försörjs från Göteborg. 

Invånarna i Öckerö kommun kunde inte förses med vatten eftersom det uppstod läckor på en av 

sjöledningarna. Leveransen till Ale kunde upprätthållas och invånarna där påverkades inte. Mölndals 

kommun drabbats inte av allvarliga läckor eller liknande under denna period, men om så varit fallet hade 

situationen kunnat bli påfrestande då möjligheten att förses med vatten från Göteborg var begränsad. 

Den ovan beskrivna händelsen visar att sammankopplingar mellan kommuner kan vara av stor vikt för 

att både täcka det dagliga vattenbehovet och fungera som reservförsörjning. Beroendet mellan 

kommunerna kan dock medföra att effekten av oönskade händelser påverkar flera kommuner, detta gäller 

både leveransavbrott och spridning av smittämnen. 

Viktiga faktorer som bidrog till att konsekvenserna av händelsen i Göteborgsområdet inte fick mer 

omfattande konsekvenser är god kommunikation, tillgång till snabba analysresultat och stöd från den 

nationella vattenkatastrofgruppen VAKA. Vissa riskreducerande åtgärder har vidtagits efter händelsen. 

Regional risk- och sårbarhetsanalys 

Det finns olika metoder och verktyg för att analysera risker och dessa har ofta olika syften (Pollard, 2008; 

Rosén et al., 2007). Livsmedelsverket (2007) presenterar en kvalitativ metod för risk- och 

sårbarhetsanalys, men den är inte specifikt anpassad för det regionala angreppssättet. En central fråga är 

hur en regional analys bör genomföras för att belysa viktiga aspekter samtidigt som detaljeringsnivån inte 

blir för omfattande? Utformningen av det här presenterade angreppssättet och de tillhörande verktygen 

baserades på följande kriterier: (1) risker kopplade till både vattenkvalitet (hälsorisk) och 

leveranssäkerhet måste beaktas, (2) analyserna skall kvantifiera risken och inte baseras på kvalitativa 

beskrivningar, och (3) effekten av riskreducerande åtgärder skall kunna kvantifieras. 

Eftersom hälsorisker och leveranssäkerhet är av olika karaktär är det lämpligt att kombinera olika 

verktyg för att analysera båda aspekterna. Genom att studera hur effektiva de mikrobiologiska barriärerna 

i respektive vattenverk är kan en bedömning göras av hälsorisken både lokalt och i regionen som helhet. 

Förmågan att reducera smittämnen jämförs med råvattenkvaliteten för att se om nuvarande förmåga är 

tillräcklig eller inte. Denna typ av analys kan genomföras på olika sätt, här används angreppssättet enligt 

God DesinfektionPraxis (GDP) som utvecklats och beskrivs av Ødegaard et al. (2009). 

Leveranssäkerheten kan analyseras genom att en modell byggs för att beskriva hur oönskade händelser 

kan inträffa i försörjningssystemet och på olika sätt leda till leveransavbrott. Metodiken som här föreslås 

gör det möjligt att ta hänsyn till sammankopplingar mellan kommuner, möjlig försörjning via 

reservvattentäkter m.m. Det föreslagna verktyget bygger på felträdsanalys och har utvecklats och tidigare 

tillämpats i dricksvattensammanhang av Lindhe et al. (2009; 2011) och Lindhe (2010). Med 

felträdstekniken kan risken uttryckas som förväntat antal avbrottsminuter per år och resultaten kan 

studeras för respektive kommun och regionen som helhet. Det är också möjligt att se hur olika delar av 

försörjningskedjan (råvatten, beredning och distribution) bidrar till den totala risken. 


Det finns alternativ till de verktyg som här föreslagits, t.ex. kan kvantitativa mikrobiella riskanalyser 

användas för att bedöma hälsoriskerna (se t.ex. Abrahamsson Lundberg et al., 2009; Haas et al., 1999). 

De föreslagna verktygen anses dock lämpliga då de ger en rimlig detaljeringsnivå, kvantifierar risken på 

ett sätt som lätt kan jämföras mellan kommunerna och effekten av åtgärder kan på ett relevant sätt 

analyseras. 

I Figur 2 beskrivs översiktligt vilken information som krävs för de olika analyserna samt vilka resultat 

som erhålls. Ytterligare beskrivning av hur verktygen tillämpas och vilka resultat de ger presenteras i 

fallstudieexemplet nedan. 

INFORMATIONSBEHOV 

Råvattendata och processparametrar, 

beskrivning av existerande barriärer, 

beskrivning av möjliga åtgärder. 

Beskrivning av händelser (från råvatten till 

tappkran) som kan leda till leveransavbrott, 

antalet brukare som drabbas, tillgången till 

reservtäkter och annan redundans, 

beskrivning av möjliga åtgärder. 

Ytterligare analyser kan genomföras för att 

belysa fler aspekter. 

Resultat från genomförda analyser, 

kostnader och annan information om 

möjliga åtgärder. 

ANALYS 

Barriäranalys 

(hälsorisker) 

Leveranssäkerhetsanalys 

Ytterligare 

analyser 

Resultatsammanställning 

RESULTAT 

Bedömning av om nuvarande barriärer är 

tillräckliga för en säker vattenförsörjning, 

behov och effekten av möjliga åtgärder. 

Risken uttryck som förväntade antalet 

avbrottsminuter per år, information om 

vilken del av systemet som bidrar mest till 

risken, osäkerheten i resultaten, behovet 

och effekten av åtgärder. 

Resultaten beror på vilken typ av analys 

som genomförts. 

Beslutsunderlag i form av nuvarande 

statusen på respektive kommuns 

vattenförsörjning och regionen som helhet, 

behovet av åtgärder, effekten av såväl 

beslutade som möjliga framtida åtgärder. 

Figur 2 Beskrivning av vilken information som krävs och vilka resultat som erhålls från respektive analys. 

Syftet med en risk- och sårbarhetsanalys är att resultaten i skall utgöra beslutsstöd då det exempelvis 

skall avgöras om nuvarande risknivå är acceptabel eller om möjliga åtgärder måste prioriteras. Den 

analys- och beslutsprocess som risk- och sårbarhetsanalysen är en del av illustreras i Figur 3. 

Syfte och omfattning 

Systembeskrivning och 

andra förutsättningar 

Analys av barriärer 

(hälsorisker) 

Leveranssäkerhetsanalays 

Ytterligare 

analyser 

Krav, mål m.m. 

Utvärdering 

Beslutsstöd 

Figur 3 Principiell beskrivning av den beslutsprocess som en regional risk- och sårbarhetsanalys är en del 

av (inspirerad av Aven, 2003). 

Illustrationen i Figur 3 visar att de analyser av barriärverkan, leveranssäkerhet och eventuella andra 

aspekter styrs av vilket syfte vi har, d.v.s. vilka frågor vi vill ha svar på och vilka beslut vi måste fatta. 

Analysresultaten måste utvärderas och ställas i relation till andra aspekter som inte behandlats i 

analyserna. Såväl vårt syfte som analyserna och utvärderingen av resultaten påverkas av de krav och mål 

som finns. Det kan handla om lagkrav, lokalt uppsatta mål eller andra beskrivningar av vad som utgör en 

acceptabel risk eller nödvändig servicenivå. Kombinationen av analysresultat och utvärderingen av dessa 

samt de krav och mål som finns ger information som kan betraktas som ett beslutsstöd. 


Fallstudieexempel 

I projektet Regional risk- och sårbarhetsanalys för centraliserad dricksvattenförsörjning genomförs en 

fallstudie med 13 kommuner i Västsverige. I inledningskapitlet beskrevs olika lösningar på 

vattenförsörjningen och många av dessa finns representerade bland fallstudiekommunerna. Detta innebär 

att vissa kommuner delar vattentäkt, det finns sammankopplingar med olika syften och detta gör 

fallstudien illustrativ. I detta avsnitt beskrivs ett exempel med sju kommuner som tagits fram för att 

illustrera viktiga delar av tillämpningen och resultaten. Exemplet är baserat på den omfattande fallstudien, 

men resultaten är inte nödvändigtvis direkt överförbara på en specifik kommun. 

Barriäranalys 

Analysen av de mikrobiologiska barriärerna har genomförts enligt God DesinfektionPraxis (GDP) 

(Ødegaard et al., 2009). Detta innebär att en nödvändig barriärhöjd bestämts utifrån råvattendata och 

antalet brukare, vilket sedan jämföts med effekten av existerande barriärer. Med barriärhöjd avses 

reduktionen av smittämnen (bakterier, virus och parasiter) uttryckt i log10-enheter (90 % reduktion 

motsvarar en log-reduktion på 1, 99 % reduktion motsvarar en log-reduktion på 2, o.s.v.). Samtliga 

kommuner i detta exempel har ytvattentäkter men vissa utnyttjar konstgjord infiltration. Generellt ligger 

barriärhöjdskravet på 5-6 log-enheter för bakterier och virus samt ca 4 log-enheter för parasiter. 

För att ta hänsyn till bl.a. osäkerheter analyserades olika driftfall i syfte att se vilka situationer som är 

mest kritiska. Ett konservativt angreppssätt bör användas eftersom optimala driftförhållanden inte alltid 

råder och barriärhöjden skall ändå vara tillräcklig. Vidare analyserades för de fall då det var aktuellt även 

effekten av beslutade åtgärder och eventuella framtida, men ej beslutade, åtgärder. Syftet med detta var 

att tydliggöra vilken barriärhöjd de olika åtgärderna ger samt var ytterligare åtgärder är nödvändiga. 

Exempelkommunerna som här analyserats illustreras i Figur 4 där också resultaten presenteras. 

i. 

ii. 

iii. 

i. 

ii. 

A 

b v p 

iii. b v p 

B 

b v p 

i. 

ii. 

iii. 

b v p 

b v p 

i. b v p 

ii. b 

iii. 

v p 

i. 

ii. 

iii. 

(2012/2022) 

C 

(2012) 

D 

b v p 

b v p 

E 

F 

b v p 

i. b v p 

ii. b 

iii. 

v p 

i. Nuvarande förhållande 

ii. Beslutade åtgärder (genomfört år) 

iii. Möjliga framtida åtgärder 

Barriärhöjden tillräcklig 

Barriärhöjden knappt tillräcklig 

Barriärnivån otillräcklig 

Session 1: Management 27 

G 

(2013) 

Figur 4 Huvudresultaten från barriäranalysen för exempelregionen med sju kommuner. 

Kommunerna A, B och C delar råvattentäkt men har idag olika beredning och därmed skiljer sig den 

uppnådda barriärhöjden. Kommun A uppfyller inte barriärkravet med avseende på något av smittämnena 

och det finns inga beslutade åtgärder för att förbättra situationen. Det finns däremot planer för hur 

situationen bör åtgärdas. Kommun B:s egen beredning uppfyller i dagsläget barriärkravet men kapaciteten 

är otillräcklig och därför förses delar av kommunen med vatten från kommun A som inte uppfyller 

kraven. Kommun C som även förser kommunerna D, E och F med vatten uppfyller inte barriärkravet för 

parasiter och under vissa driftfall är barriärhöjden även otillräcklig för virus. Det finns dock ett beslut om 

att installera membranfilter för att uppfylla kraven. Av olika anledningar förväntas installationen av 

membranfilter kunna var klar först 2022 och som en övergångslösning installeras därför UV 2012. 

Kommun D har egen vattentäkt men förses även till viss del med vatten från kommun C. Den egna 

produktionen har idag otillräckliga barriärer mot parasiter. Det finns planer för att förbättra beredningen, 

men inget slutgiltigt beslut har fattats. Kommun E förses med råvatten från en egen ytvattentäkt och har 

otillräckliga barriärer mot parasiter och ligger på gränsen för virus. För att åtgärda denna situation har ett 

beslut fattas om att installera UV som en ytterligare barriär (2012). Kommun E köper en viss mängd 

vatten från kommun C som har motsvarade situation vad gäller barriärhöjden. Det finns även en

sammankoppling mellan kommunerna E och G, vilken framförallt används för att förse delar av kommun 

G med vatten men vid behov kan även kommun E försörjas med vatten. Både kommun D och E är 

därmed till viss del beroende av att det finns tillräckliga barriärer i kommun C. 

Kommun F saknar egen produktion och försörjs uteslutande med vatten från kommun C. Redan i 

dagsläget har kommun E installerat UV i anslutningspunkten till kommun C vilket gör att barriärhöjden 

bedöms vara tillräcklig. Kommun G har egen vattentäkt och produktion som idag bedöms otillräcklig med 

avseende på framförallt parasiter men till viss del även virus. Uppgraderingar av beredningen är beslutade 

vilket (2013) kommer att ge en tillräcklig barriärhöjd. 

Resultaten visar att det krävs åtgärder i kommunerna A och D. Vattenkvaliteten i kommun A påverkar 

även kommun B dit en viss mängd vatten leveras. Leveransen mellan kommunerna visar också att en 

störning i en kommun kan påverka brukarna i andra kommuner. Genomförandet av vissa typer av 

åtgärder kan ta lång tid och då kan tillfälliga löningar såsom för kommun C vara viktiga. För vissa 

kommuner rekommenderas att ytterligare råvattenanalyser görs för att en säkrare bestämning av 

kvalitetskravet skall kunna göras. Ett konservativt angreppssätt har dock använts för att inte överskatta 

råvattenkvaliteten. Utifrån angreppssättet enlig GDP kan det för vissa kommuner konstateras att 

ytterligare åtgärder på råvattensidan skulle kunna ge en större säkerhetsmarginal vad gäller barriärhöjden. 

Leveranssäkerhet 

Leveranssäkerheten i respektive kommun har analyserats med hjälp av en felträdsmodell (Lindhe, 2010) 

som byggts för att beskriva hur leveransavbrott kan uppstå baserat på interaktionen mellan händelser 

såsom rörbrott, förorening av vattentäkt, pumphaveri, försörjning via reservtäkter eller annan kommun 

m.m. För de kommuner som t.ex. delar vattentäkt eller är sammankopplade har modellerna länkats, vilket 

innebär att en händelse kan påverka flera kommuner och därmed beaktas de beroenden som finns. I Figur 

5 illustreras översiktligt vilka händelser som kan ingå i en felträdsmodell. Modellen visar att hänsyn tas 

till om vatten kan levereras från en annan kommun, var i systemet felen uppstår och vilken möjlighet det 

finns att kompensera för felen via det egna systemet (reservtäkter, reservoarer m.m.) eller leverans från en 

annan kommun. Observera att i en modell beskrivs händelserna mer ingående med olika delhändelser. 

Avbrott i lev. från 

annan kommun 

Leveransavbrott 

Problem i annan 

kommun 

Ej kompensation 

via eget system 

Fel i råvattenförsörjning 

Råvattenfel 




via annan 

Figur 5 Översikt över huvudhändelser som kan ingå i en felträdsmodell. 

Fel i beredning Fel i distribution 

Beredningsfel 




via annan 

Distributionsfel 




via annan 

För att illustrera tillämpningen av felträdstekniken studeras här kommunerna C-G, vilka på olika sätt är 

sammankopplade (Figur 4). Kommun C har en central funktion och levererar ca 20 % av vattenbehovet 

till kommunerna D och E samt 100 % till kommun F. Kommun C kan dock vid krislägen och under viss 

tid täcka hela behovet i kommun D och E. Kommun G köper en mindre mängd vatten från kommun E, 

men sammankopplingen fungerar framförallt som en reserv för att under kortare tider kunna försörjas 

med vatten. Baserat på identifierade oönskade händelser samt information om hur ofta de kan inträffa, hur 

långvariga de är och hur många brukare som kan förväntas drabbas av olika leveransavbrott, byggdes en 

felträdsmodell för respektive kommun. Felträdsmodellerna för de olika kommunerna justerades så att 

även effekten av olika åtgärder/förändringar i systemen skall kunna analyseras. 

Felträdsmodellerna ger olika resultat, t.ex. risknivån uttryckt som förväntat antalet avbrottsminuter 

minuter per år för genomsnittsbrukare. I Figur 6 visas resultat från det exempel vi här studerar. Resultaten 

som beskrivs är risknivåerna för nuvarande system (6a), förväntade risknivåer efter det att kapaciteten i 

kommun C kraftigt ökats (6b) samt detaljerade risknivåer för kommun C efter kapacitetsökningen. 

Genom att indata till modellerna beskrivits med osäkerhetsfördelningar kan även osäkerheterna i 

resultaten presenteras, d.v.s. utöver medelvärdet presenteras även 5- och 95-percentilen (P05 och P95). 


Resultaten i Figur 6a visar risknivåerna för respektive kommun i nuläget. Det framgår att risknivåerna 

är högst för kommunerna C och D. Orsaken till detta illustreras delvis i Figur 4 där det framgår att 

kommun C saknar reservförsörjning från någon annan kommun. Kommun har dock denna reserv via 

kommun C men det finns begränsningar i kommunen som ger upphov till den relativt höga risken. 

Observera att resultaten inte presenteras separat för kommun F utan ingår i detta exempel i resultaten för 

kommun C. Kommun F försörjs med vatten uteslutande från kommun C, vilket gör att risknivåerna är 

tämligen lika för dessa kommuner. För att utvärdera risknivåerna måste de jämföras med en acceptabel 

nivå. I kommun C finns ett mål uppsatt som säger att medelbrukaren inte skall drabbas av leveransavbrott 

mer än 10 dygn under 100 år. Detta kan översättas till 144 avbrottsminuter per år för genomsnittbrukaren, 

vilket då kan jämföras med resultaten i Figur 6. Denna typ av mål finns inte fastställt för övriga 

kommuner, men om 144 min/år antas vara allmängiltigt framgår det att risken generellt är oacceptabel. 

Det finns ett beslut taget i kommun C om att öka kapaciteten i syfte att bl.a. förbättra 

leveranssäkerheten. Baserat på den effekt åtgärden förväntas ha på systemet har indata till modellen och 

modellstrukturen uppdaterats. Resultaten (Figur 6b) visar att kapacitetsökningen har en stor effekt på 

kommunerna C och D och en mindre effekt på kommunerna E och G. 

Leveranssäkerhetsanalysen ger möjlighet att analysera vilken del av systemet som bidrar mest till den 

totala risken, d.v.s. vilken del av systemet som initialt påverkas av en händelse och i slutändan orsakar 

leveransavbrott. I Figur 6c illustreras detta för kommun C där risknivåerna motsvarar situationen efter den 

beslutade kapacitetsökningen. Det framgår att händelser i råvattenförsörjningen och distributionen bidrar 

ungefär lika mycket och beredningen har ett lägre bidrag. Analyserar man ytterligare resultat 

(felintensitet, sannolikheten och varaktigheten för olika händelser samt antalet drabbade brukare) framgår 

det att händelser i råvattenförsörjningen inträffar sällan men kan påverka många brukare och vara 

långvariga. För händelser på distributionssidan är förhållandena de omvända, d.v.s. händelserna inträffar 

relativt ofta, har kort varaktighet och påverkar normalt sätt relativt få brukare. Jämförs resultaten i Figur 

6c med målet på högst 144 avbrottsminuter per år för genomsnittsbrukaren framgår det att medelvärdet 

klart ligger under denna nivå, men p.g.a. osäkerheterna finns det en viss sannolikhet att överstiga målet 

(8 %). Denna information är viktig då det beslutas om målet är uppfyllt eller inte. På motsvarande sätt 

som kapacitetsökningen i kommun C har analyserats kan nya sammankopplingar mellan kommunerna 

och andra förändringar i systemen analyseras. 

Avbrottsminuter per år och brukare 

1 800 

1 600 

1 400 

1 200 

1 000 

800 

600 

400 

200 

0 

6a 

P05 

Medel 

P95 

C D E G 


1 800 

1 600 

1 400 

1 200 

1 000 

800 

600 

400 

200 

0 

6b 

C D E G 

Session 1: Management 29 

P05 

Medel 

P95 


200 

180 

160 

140 

120 

100 

80 

60 

40 

20 

0 

6c 

P05 

Medel 

P95 

Tot. Råv. Ber. Dist. 

Figur 6 Resultatsammanställning för leveranssäkerhetsanalysen för kommunerna C-G. Till vänster (6a) 

presenteras risknivåerna för nuvarande system, i mitten (6b) resultatet efter kapacitetsökning i kommun C 

och till höger (6c) detaljerade risknivåer för kommun C efter kapacitetsökning. 

Diskussion och slutsatser 

Fallstudieexemplet som presenterats i denna artikel visar att en regional risk- och sårbarhetsanalys kan ge 

information om risken kopplad till både vattenkvalitet/hälsorisk och leveranssäkerhet för respektive 

kommun samt regionen som helhet. För exempelkommunerna A-G tydliggjordes det huruvida nuvarande 

barriärer är tillräckliga, var beslut om åtgärder fattats och om dessa är tillräckliga samt var ytterligare 

åtgärder är nödvändiga. På motsvarande sätt visar leveranssäkerhetsanalysen det förväntade antalet

avbrottsminuter per år och hur åtgärder förändrar risken. En viktig aspekt är möjligheten att analysera 

riskreducerande åtgärder och att effekten kan studeras såväl lokalt som regionalt. Beroendet mellan 

kommunerna kan ha en stor inverkan på risken och åtgärder i en kommun kan komma till nytta för flera 

andra, precis som att problem i en kommun kan fortplanta sig. Även om vattenförsörjningen i en specifik 

kommun i dagsläget inte är beroende av andra kommuner är en regional analys värdefull eftersom det 

visar möjligheter och begränsningar för t.ex. reservvattenförsörjning. 

För att avgöra huruvida riskreducerande åtgärder är nödvändiga eller inte måste nuvarande risknivå 

jämföras med en acceptabel nivå. För barriäranalyserna är acceptanskriteriet inbyggt i kravet på 

barriärhöjd, men för leveranssäkerhetsanalys finns inget sådant. I fallstudien antogs det mål på maximalt 

144 avbrottsminuter per år vilket används i en av kommunerna. Leveranssäkerhetsanalysen bidrar därmed 

till diskussionen om vilka mål och krav som bör ställas. Vidare tydliggör både barriär- och 

leveranssäkerhetsanalyserna frågan om vilka resurser som anses rimliga att satsa för att uppnå målen. 

Erfarenheterna från projektet om regional risk- och sårbarhetsanalys visar att de verktyg (GDP och 

felträdsanalys) som tillämpats är väl lämpade för regionala analyser. Genom det regionala angreppssättet 

identifieras och konkretiseras de beroenden som finns mellan kommuner med avseende på både hälsorisk 

och leveranssäkerhet. Tack vare att risknivåerna kvantifieras underlättas bl.a. jämförelsen av åtgärder. 

Väl genomförd kan en regional risk- och sårbarhetsanalys ge värdefull och användbar information som 

kan underlätta VA-planeringen på kort och lång sikt. Tydliggörandet av nuvarande risknivå och effekten 

av möjliga riskreducerande åtgärder ger ett bra beslutsunderlag som också kan underlättar samarbetet 

mellan olika kommuner. 

Fortsatt arbete 

Projektet om regional risk- och sårbarhetsanalys för dricksvattenförsörjning kommer att avslutas under 

hösten 2012. Resultaten kommer att redovisas i en vägledning som syftar till att visa hur regionala risk- 

och sårbarhetsanalyser kan genomföras, vilken information som krävs, vilka resultat som erhålls m.m. 

Tack 

Författarna vill tacka Myndigheten för samhällsskydd och beredskap för finansieringen av projektet. Ett 

stort tack riktas också till fallstudiekommunerna (Ale, Alingsås, Göteborg, Härryda, Kungsbacka, 

Kungälv, Lerum, Lilla Edet, Mölndal, Partille, Stenungsund, Tjörn och Öckerö) samt Göteborgsregionens 

kommunalförbund för det goda samarbetet som varit avgörande för ett lyckat projekt. 

Referenser 

Abrahamsson Lundberg J., Ansker J. & Heinicke G. (2009). MRA – Ett modellverktyg för svenska vattenverk, 

Rapport 2009-05, Svenskt Vatten Utveckling, Stockholm. 

Aven, T. (2003). Foundations of risk analysis a knowledge and decision-oriented perspective, Wiley, Chichester. 

CDW/CCME (2004). From source to tap: Guidance on the Multi-Barrier Approach to Safe Drinking Water, Federal- 

Provincial-Territorial Committee on Drinking Water and Canadian Council of Ministers of the Environment 

Water Quality Task Group, Health Canada. 

Haas C. N., Gerba C. P. & Rose J. B. (1999). Quantitative microbial risk assessment, Wiley, New York. 

IWA (2004). The Bonn Charter for Safe Drinking Water, International Water Association, London. 

Lindhe (2010). Riskanalys från råvatten till tappkran, Rapport 2010-08, Svenskt Vatten Utveckling, Stockholm. 

Lindhe, A., Rosén, L., Norberg, T. & Bergstedt, O. (2009). Fault tree analysis for integrated and probabilistic risk 

analysis of drinking water systems, Water Research, 43 (6), 1641-1653. 

Lindhe, A., Rosén, L., Norberg, T., Bergstedt, O. & Pettersson, T.J.R. (2011). Cost-effectiveness analysis of riskreduction 

measures to reach water safety targets, Water Research, 45 (1), 241-253. 

Livsmedelverket (2007). Risk- och sårbarhetsanalys för dricksvattenförsörjning, 

NHMRC/NRMMC (2004). National Water Quality Management Strategy: Australian Drinking Water Guidelines, 

National Health and Medical Research Council and Natural Resource Management Ministerial Council, 

Australian Government. 

Pollard, S.J.T. (2008). Risk Management for Water and Wastewater Utilities, IWA Publishing, London. 

Rosén, L., Hokstad, P., Lindhe, A., Sklet, S. & Røstum, J. (2007). Generic framework and methods for integrated 

risk management in water safety plans, Deliverable no. D4.1.3, D4.2.1, D4.2.2, D4.2.3, TECHNEAU. 

Riksrevisionen (2008). Dricksvattenförsörjning – beredskap för stora kriser, Riksrevisionen 2008:8, Stockholm. 

Ødegaard, H., Østerhus, S. & Melin, E. (2009). Veiledning til bestemmelse av god desinfektionspraksis, 170 - 2009, 

Norks Vann, Hamar. 


Exempel på och erfarenheter av svenska arbetsmetoder för 

HACCP 

Maria Bennet 1) , Johanna Westlund 2) , Derek Sutton 3) 

1) WSP Sverige AB, Laholmsvägen 10, 302 66 Halmstad, maria.bennet@wspgroup.se 

2) WSP Sverige AB, Lagergrens gata 8, 651 04 Karlstad, johanna.westlund@wspgroup.se 

3) WSP Sverige AB, 121 88 Stockholm-Globen, derrek.sutton@wspgroup.se 

Abstract 

According to the EU's hygiene regulation (852/2004/EC), companies are responsible for food safety, that 

hygiene rules are followed and that monitoring plans are based on HACCP (Hazard Analysis and Critical 

Control Point) principles. Industry guidelines on hygiene practices and how HACCP can be applied are 

important tools. The EU's Drinking Water Directive (98/83/EC) and hygiene regulation defines the quality of 

drinking water for human consumption from the time it reaches the consumer at the tap. The Swedish 

National Food Agency has defined regulations for drinking water for human consumption from the time 

withdrawal occurs from the source throughout delivery to the consumer’s tap. From January 1, 2012 

Swedish drinking water regulations require hygiene rules and HACCP to drinking water, protecting the 

chain from source to tap. 

The World Health Organization (WHO) has developed "Guidelines for Drinking Water Quality", which 

includes working with the Water Safety Plans (WSP). It is expected that this type of risk management will 

be included in coordination with the next revision of the EU's Drinking Water Directive in 2013. Sweden is 

considered at the forefront in this area in large part due to drinking water and water management 

regulations as these requirements include the creation of source water protection areas and the 

implementation of HACCP. 

HACCP is a system to prevent risks that impair water quality. The Swedish Water Association has 

developed a manual for self-monitoring with HACCP where guidance is available for identifying risks. Risks 

are based on the health hazards caused by microbial or chemical contamination that can occur in the 

water source, within the water treatment process or in the distribution network. A risk may, for example, be 

caused by a work routine or instruction that is missing or unclear, or a process step that does not provide 

adequate function. For each risk, the type of health hazard, the cause of the health hazard and the existing 

preventive measures are identified, plus whether the monitoring is measured online. The next step is to 

determine whether the risk is a critical control point (CCP). For the risks that are considered as CCPs, 

critical limits should be set for key parameters measured on-line. A critical limit is an alarm level with a 

margin of safety, so that corrective measures can be taken to prevent hazards to human health. 

Useful tools in HACCP include methods for good disinfection practices (GDP, guidance from the 

Norwegian Water Association) and quantitative microbiological risk analysis (MRA, modeling tools 

developed by the Swedish Water Association adapted for Swedish water utilities). 

Vad är HACCP? 

Enligt EU’s hygienförordning (EG 852/2004) ska företag ansvara för att livsmedel är säkra, att regler om 

hygien följs och att kontrollplaner bygger på HACCP-principerna (Hazard Analysis and Critical Control 

Point). I EU’s dricksvattendirektiv (EG 98/83) och hygienförordningen definieras dricksvattnet som 

livsmedel från det att det når konsumenten vid tappkranen och det är således från tappkranen som 

hygienförordningen tillämpas. De svenska dricksvattenföreskrifterna däremot, omfattar hygienregler och 

HACCP i hela kedjan från uppfodring till tappkran, vilket tydliggjorts från 1 januari 2012. 


Världshälsoorganisationen, WHO, har tagit fram “Guidelines for Drinking Water Quality” som omfattar 

arbetssätt med Water Safety Plans (WSP). Som ett minimum för att försäkra sig om att dricksvattnet är 

säkert omfattar WSP en bedömning av systemet från råvatten till tappkran (farobedömning), en effektiv 

operativ övervakning samt förvaltning av systemet (vid normal drift, incidenter och för åtgärder) och 

WSP omfattar också dokumentations- och kommunikationsrutiner. Vid nästa översyn av EU’s 

dricksvattendirektiv 2013, förväntas denna typ av riskhantering inkluderas i dricksvattendirektivet. Här 

bedöms Sverige ligga i framkant tack vare dricksvattenföreskrifterna med krav på HACCP och 

Vattenförvaltningsförordningen med krav på skydd av dricksvattenförekomster. 

Svenskt Vattens branschriktlinjer för HACCP 

HACCP är ett system för att förebygga risker som ger försämrad dricksvattenkvalité. HACCP grundar sig 

på sju principer enligt följande. 

Princip 1: Utför faroanalys. 

Princip 2: Bestäm kritiska styrpunkter, CCP. 

Princip 3: Fastställ kritiska gränser. 

Princip 4: Skapa ett system för övervakning av CCP. 

Princip 5: Fastställ korrigerande åtgärder som ska vidtas när övervakning indikerar att en viss 

CCP inte är under kontroll. 

Princip 6: Fastställ verifieringsmetoder för att bekräfta att HACCP-systemet fungerar effektivt. 

Princip 7: Fastställ dokumentation över alla rutiner och journaler som krävs för dessa principer 

och tillämpningen av dem. 

Svenskt Vatten har tagit fram en handbok för egenkontroll med HACCP som är en vägledning för 

upprättande av grundförutsättningar/allmänna hygienregler (rutiner), HACCP-analys och rutiner för 

exempelvis kontroll i efterhand (provtagningsprogram) och kommunikation. När det gäller HACCPanalysen 

utgår riskerna från hälsofaror orsakat av mikrobiell eller kemisk förorening. En risk kan 

exempelvis orsakas av att en rutin/instruktion saknas eller är otydlig eller att ett beredningssteg inte ger 

tillräcklig reningseffekt. För varje risk anges typ av hälsofara, orsaken till hälsofaran, befintliga 

förebyggande åtgärder och om övervakning sker online. 

Nästa steg är att avgöra om risken är en kritisk styrpunkt, det vill säga CCP (Critical Control Point). För 

de risker som bedöms som CCP ska kritiska gränser fastställas för viktiga parametrar som mäts online. En 

kritisk gräns är en larmnivå som är satt så att åtgärder kan vidtas för att förhindra hälsofaran. Om en 

kritisk gräns överskridits ska korrigerande åtgärder, för återställning till ett godtagbart läge, anges för 

respektive CCP. Det är därför viktigt att larmnivån (kritiska gränsen) har god marginal till oacceptabel 

hälsorisk då det ger tid att åtgärda problemet. En CCP kan således kontrolleras på ett effektivt sätt genom 

online-mätning, men övriga risker baserade på rutiner, underhåll, organisation, etc. kan vara svårare att 

effektivt kontrollera. 

CCP identifieras med hjälp av ett beslutsträd med frågor om det finns förebyggande åtgärder eller kontroll 

(vattenskydd, provtagning, övervakning, egenkontroll) och om det finns processteg eller hantering som är 

specifikt anpassade för att minska hälsofaran till en acceptabel nivå. De risker som identifieras och som 

inte kan övervakas online är inte CCP, men behöver inkluderas i egenkontrollen genom en 

rutin/instruktion eller genom en direkt åtgärd (exempelvis installation av utrustning). 

I HACCP-analysen kan sammanfattningsvis riskerna värderas. Detta är inget obligatoriskt moment men 

den här delen av HACCP gör att systemet blir ett verktyg för att prioritera åtgärder. Utifrån de befintliga 

förutsättningarna på vattenverket och distributionsanläggningen görs en bedömning av riskens 

konsekvens, sannolikhet och frekvens som vägs samman till ett risktal. 

Användbara verktyg tillsammans med HACCP är metoden för god desinfektionspraxis, GDP (vägledning 

från Norsk Vann) samt kvantitativ mikrobiologisk riskanalys, MRA (modellverktyg framtaget av Svenskt 

Vatten Utveckling anpassat för svenska vattenverk). Dessa ger en fördjupad kunskap om de 

mikrobiologiska barriärernas effekt. 


Genomförande av HACCP och exempel på resultat 

Vid genomförandet av HACCP bildas en grupp med projektledare och driftspersonal. Inledningsvis hålls 

en övergripande diskussion om hälsorisker och förebyggande åtgärder i råvattnet, kemikaliehantering, 

beredningsstegen och distributionsanläggningen. 

Vattentäkt 

Vid diskussion om hälsorisker i vattentäkten görs en genomgång av det befintliga skyddet. Finns 

vattenskyddsföreskrifter och efterföljs dessa? Vilka trafiksäkerhetsåtgärder har vidtagits? Har en risk- och 

sårbarhetsanalys genomförts? Finns en kris- och beredskapsplan för dricksvattenförsörjningen? Hur är 

kontrollen av råvattenkvalitén? 

Resultaten sammanfattas i HACCP-analysen och kan exempelvis leda till att skyddet av vattentäkten 

behöver förstärkas eller att kontinuerlig övervakning av råvattenkvalitén behövs. En sådan 

råvattenövervakning möjliggör styrning för driftsoptimering av vattenverkets beredningssteg. Lämpligen 

genomförs en MRA-modell av vattenverket för att öka kunskapen om den mikrobiologiska 

barriäreffekten utifrån variationer i råvattenkvalitén. 

Vattenverk 

En bedömning av möjliga hälsofaror (mikrobiella, kemiska, fysikaliska) genomförs i respektive 

beredningssteg i vattenverket. För varje hälsofara anges orsaken till den och vilka förebyggande åtgärder 

som finns. På vattenverket görs därför en grundlig genomgång av beredningsstegens utrustning, 

underhåll, drift, dimensionering, övervakning, rutiner och erfarenheter från inträffade incidenter. 

Ett exempel på resultat av en HACCP-analys i vattenverk är övervakning av turbiditet. I vattenverk med 

kemisk fällning och sandfiltrering är turbiditet en parameter som övervakas och är CCP. Gränsvärdet 

enligt dricksvattenföreskrifterna på utgående dricksvatten är 0,5 FNU eller NTU. På vattenverk 

förekommer att larmen är på samma nivå som gränsvärdet, vilket gör att larmnivån behöver justeras. Den 

normala variationen på turbiditeten ut från filtrerna kontrolleras för att bestämma halten för 

uppmärksamhetsnivån, d.v.s. den nivå när det sker en tydlig avvikelse från det normala. Nästa steg är att 

fastställa larmnivån där en direkt åtgärd måste vidtas för att inte överstiga gränsvärdet. Dessa kritiska 

gränser ska leda till att hälsorisken förebyggs genom en effektiv övervakning. 

Följande figur visar hur turbiditeten kan variera ut från ett beredningssteg med kemisk fällning och 

snabbsandfilter. På detta vattenverk mäts turbiditeten online på utgående vatten från respektive filter, 

vilket då tydligt visar hur respektive filter fungerar. Resultatet av genomförd HACCP är att larmnivåerna 

behöver justeras och att åtgärder behöver vidtas för att optimera beredningssteget, enligt tabellen nedan. 

HACCP-analysen har kompletterats med resultat från GDP, som visar att detta beredningssteg inte kan 

tillräknas som en pålitlig mikrobiologisk barriär och åtgärder behöver därför vidtas. 


Figure 1 Exempel på turbiditet från tre linjer efter kemisk fällning och sandfiltrering. Topparna visar 

turbiditet vid filterspolning. 

Table 1 Exempel kritiska gränser före och efter genomförd HACCP. 

Kritiska gränser 

Larmnivå innan genomförd HACCP 0,50 FNU 

Kritiska gränser efter genomförd HACCP 

Uppmärksamhetsnivå 0,15 FNU 

Larm för åtgärd 0,20 FNU 

Distributionsanläggning 

Det är viktigt att också distributionsanläggningarna besöks vid genomförandet av HACCP. När det gäller 

ledningsnätet genomgås rutiner för anläggningsarbete och arbete vid akuta läckor, uttag av vatten via 

brandposter, desinfektion av ledningsnätet, spolplaner samt underhåll av utrustning/installationer som 

exempelvis luftarventiler, brand- och spolposter, sprinklersystem och återströmningsskydd. Det är också 

viktigt att känna till förekomst av förorenad mark i områden med dricksvattenledningar på grund av risk 

för föroreningspåverkan. Samtliga reservoarer avstäms avseende utformning av bräddavlopp, ventilation, 

tak/väggar, reservoarluckor samt befintliga rutiner för underhåll, rengöring av lokaler och reservoarer 

samt vattnets uppehållstider. 

Exempel på resultat av HACCP-analys för distributionsanläggningen är att rutiner behöver dokumenteras 

eller att nödvändiga åtgärder behöver vidtas, som exempelvis att förse ventilationsrör med insektsnät eller 

pollenfilter och reservoarluckor med tätlister. Det förekommer att bräddavlopp inte har vattenlås och/eller 

att bräddavloppen är kopplade till spillvattenledning, vilket är allvarligt och leder till förebyggande 

åtgärder. 


Erfarenheter 

Vad är erfarenheterna av att genomföra en HACCP-analys och hur användarvänlig är sammanställningen 

med alla risker och risktal? 

Erfarenheterna visar att genomförandet med besök på alla anläggningar är betydelsefull. Personalen kan 

då gemensamt se statusen utifrån ett hygienperspektiv och förstå synsättet med hälsorisker i en HACCP. 

Det har visat sig att sammanställningen av riskerna i Excel innehåller mycket information och att den 

därför behöver förklaras för att tydliggöra upplägget. Resultatet av riskerna kan redovisas på alternativa 

sätt så att det passar den enskilde kommunen. Efter att den första HACCP-analysen sammanställts 

fortsätter det förebyggande arbetet. Exempelvis kan de prioriterade riskerna vara en stående punkt på 

agendan vid driftsmöten så att det finns ett tydligt fokus på HACCP-arbetet. När en åtgärd genomförts 

omvärderas frekvens, konsekvens och sannolikhet och på det viset jobbar man med att minska riskerna 

med hjälp av analysen. Ofta upplevs det som enklare att göra specifika tekniska åtgärder än att arbeta med 

dokumentation av rutiner och instruktioner. 

Ytterligare en erfarenhet är att det efter HACCP-analysen görs en omplacering av mätpunkterna för 

övervakning av CCP och att nivåer för larm ändras så att marginalen ökar för att med säkerhet uppnå 

hälsosamt dricksvatten. Det är också bra med förslag och påpekanden om åtgärder som framgår av 

analysen samt att HACCP kan användas som underlag för handlingsplaner tack vara bedömning av 

risktal. 

Sammanfattning 

Till skillnad från andra livsmedel går det inte att återkalla ett dricksvatten som distribuerats. Det är därför 

mycket viktigt att ha kontroll på hela dricksvattenproduktionen från råvara till produkt som rinner ur 

kranen. HACCP är ett användbart verktyg för systematisk riskhantering och resultatet innebär att 

hälsorisker har beaktats och värderats från vattentäkt via vattenverk och vidare ut till användarna. 

HACCP-analysen bedömer däremot inte leveranssäkerheten i systemet, då det är kvalité som regleras i 

dricksvattenföreskrifterna. 

Sammanfattningsvis ger HACCP-analysen följande resultat: 

Kritiska styrpunkter (CCP) och larmnivåer för kontroll av beredningen 

Eventuella brister i själva egenkontrollen (rutiner och instruktioner) 

Förebyggande åtgärder som behöver vidtas 

Behov av ytterligare kunskap 

Rangordnad prioritet av riskerna, används som underlag i handlingsplaner 

Ökad samsyn och kunskap om hälsorisker 

Referenser 

Livsmedelsverket (2011). Statens livsmedelsverks föreskrifter om dricksvatten SLVFS 2001:30 om 

dricksvatten. 

C. Johansson (2011). Säkrare dricksvatten, Svenskt Vatten konferens 2011-11-15 

M. Bennet (oktober 2010). Verktyg för systematisk riskhantering, Svenskt Vatten nr 5, 18-19. 

Svenskt Vatten (2007-06-26). Dricksvatten: Produktion och Distribution, Handbok för 

Egenkontrollprogram med HACCP. 

M. Bennet (2006-2012). HACCP för 30 vattenverk i Sverige. 

Norsk Vann (2009). Veiledning til bestemmelse av god desinfeksjonspraksis, Norsk Vann rapport 170. 

J. Lundberg Abrahamsson, m fl (2009). MRA – Ett modellverktyg för svenska vattenverk, Svenskt Vatten 

Utveckling nr 2009-05. 



M. Bondelind*, A. Malm**, O. Bergstedt**, J. Lindgren***, T.J.R. Pettersson**** 

* Chalmers, Inst. för Bygg- och miljöteknik 412 96 Göteborg, mia.bondelind@chalmers.se 

** Göteborg Vatten, Box 123, 42423 Angered 

*** Svenskt Vatten, Box 47 607, 117 94 Stockholm 

**** Chalmers, Inst. för Bygg- och miljöteknik 412 96 Göteborg 

Abstract. The Swedish Water & Wastewater Association has initiated a benchmarking project to assess the quality 

and quantity, safety and efficiency of drinking water systems in Sweden. An important part of the project is to develop 

a benchmarking model which provides a useful tool for the municipalities to evaluate the status of their drinking water 

systems in respect to a safe drinking water quality and quantity. The increased focus on a safe drinking water, in 

terms of microbiological contaminants, originates from recent outbreaks of waterborne diseases in Östersund and 

Skellefteå in Sweden. The derived benchmarking model presented in this paper evaluates the safety of the water by a 

few carefully selected parameters. The model will apply to both small and large drinking water systems and will 

provide a useful tool for comparison of drinking water systems within Sweden to encourage for a continued 

improvement of the systems. In addition, the model provides a straightforward and transparent tool for the 

municipalities to communicate the status of the drinking water systems to the public. 

Introduktion 

De flesta verksamheter strävar efter att effektivisera och förbättra sin verksamhet. Detta gäller även för 

vattentjänstbranschen (Vieira et al. 2008; Alegre et al. 2010; Balmér 2010). I Norge genomförs en årlig 

tillståndsvärdering av hela va-verksamheten indelad i vatten- respektive avloppsystem (Norsk Vann 2011). Syftet är 

att kunna visa tillståndet för det kommunala vattnet i Norge och ge kommunen en värdering av standarden av 

vattenproduktionen. Tillståndsvärderingen kan även användas för att förmedla resultat och visa på resursbehovet till 

kommunpolitiker. Datainsamlingen, som sker på vattenverksnivå, läggs sedan samman och presenteras på 

kommunnivå. Standarden på kommunens tjänster mäts med fem parametrar: Hygieniskt säkert vatten, Vattenkvalitet, 

Leveranssäkerhet, Alternativ försörjning och Ledningsnätets funktion. Parametrarna har tagits fram för att passa både 

små och stora vattenverk och de täcker in områdena råvatten, beredning och distribution. Varje parameter består av 

ett antal nyckeltal som värderas utifrån framtagna kriterier och acceptabla gränsvärden. De fem parametrarna 

betygsätts slutligen enligt skalan God, Otillräcklig samt Dålig. 

Sjukdomsutbrott orsakade av dricksvattnet i både Östersund och Skellefteå har aktualiserat frågan om ett säkert 

dricksvatten. I ett led att utveckla och utvärdera dricksvattensystemen och möjliggöra värdering av, i första hand, en 

säker produktion av dricksvatten har Svenskt Vatten initierat ett benchmarkingprojekt. Målsättningen med 

benchmarking är en systematisk jämförelse av verksamheten vilken leder till en utveckling och effektivisering av 

denna. 

Ett ramverk för en benchmarkingmodell för att beskriva tillståndet för vattenberedningen i Sveriges kommuner 

utifrån ett konsumentperspektiv presenteras i denna artikel. Det övergripande målet med modellen är att driva på 

utvecklingen mot ett säkrare dricksvatten samt att öka användandet av mikrobiologiska riskvärderingar. Genom väl 

definierade parametrar kan modellen mäta och värdera en säker dricksvattenkvalitet. 

Modellutveckling 

En första version av en benchmarkingmodell utifrån ett konsumentperspektiv presenteras i denna artikel. Den 

framtagna modellen ska övergripande visa om en säker dricksvattenkvalitet har uppnåtts i en kommun. Modellen 

baseras på den norska tillståndsvärderingen. 

Benchmarkingmodellen belyser hur långt en kommun har nått med att tillhandahålla en säker dricksvattenkvalitet 

baserat på tre parametrar: Hälsomässigt säkert vatten, Vattenkvalitet och Leveranssäkerhet, Tabell 1. Dessa tre 

parametrar består i sin tur av ett antal kriterier vilka värderas utifrån framtagna gränsvärden, Tabell 2. Genom 


gränsvärdena kan de tre övergripande parametrarna värderas på en skala från God till Otillräcklig till Dålig enligt 

uppfylld dricksvattenkvalitet. Det är viktigt att notera att denna modell endast behandlar råvatten och beredning 

eftersom distributionsnätet har behandlats i tidigare projekt. 

Tabell 1 Ramverket för benchmarkingmodellen bygger på tre parametrar, vilka består av ett antal kriterier. 

Parameter Kriterier 

Hälsomässigt säkert vatten H1 

H2 

H3 

Vattenkvalitet V1 

V2 

V3 

Leveranssäkerhet L1 

L2 

Rutinprov med anmärkning: Otjänligt 

Uppföljning och åtgärder 

Förenklad GDP (God Desinfektionspraxis) 

Rutinprov med anmärkning: Tjänligt med anmärkning 

Uppföljning och åtgärder 

Registrering och uppföljning av klagomål 

Tidsperiod som alternativ försörjning räcker 

Alternativ försörjning vid utslaget vattenverk 

Hälsomässigt säkert vatten 

Parametern Hälsomässigt säkert vatten säkerställer att vattnet är säkert att dricka utan att konsumenten bli sjuk. 

Parametern bedöms utifrån tre kriterier, Tabell 1. Gränsvärden som måste uppnås för att erhålla värderingen God, 

Otillräcklig eller Dålig status anges i Tabell 2. 

Det första kriteriet mäter andelen rutinprov tagna på utgående vatten från vattenverket samt ute på ledningsnätet 

som bedömts som ’Otjänliga’. Rutinprover tas kontinuerligt och antalet prov som tas är reglerade i 

Livsmedelsverkets föreskrifter om dricksvatten (SLVFS 2001:30) och baseras på antalet brukare. Varje prov bedöms 

enligt skalan tjänligt, tjänligt med anmärkning och otjänligt. I proven bedöms både vattenkvalitet samt 

mikrobiologisk förekomst. 

Det andra kriteriet säkerställer att rutinproven som bedömts som ’Otjänliga’ systematiskt följs upp och utreds. 

Det tredje kriteriet gäller att en förenklad GDP (God Desinfektionspraxis) ska utföras för varje vattenverk. GDP, 

tidigare benämnd ODP (Optimal desinfeksjonspraksis), är en metod som utvecklats i Norge (Norsk Vann 2009). 

Metoden ger en indikation på om man uppfyller de mikrobiologiska kraven för dricksvatten genom att en 

barriärshöjd beräknas. Barriärshöjden ger ett mått på hur stor avskiljning som krävs vid vattenverket för att uppnå ett 

mikrobiologiskt säkert dricksvatten. Metoden är anpassad för norska förhållanden och relativt krävande att utföra. 

Därför kommer en förenklad GDP-modell att utvecklas inom ramen för benchmarkingprojektet. Den förenklade 

GDP:n genomförs för varje vattenverk och resultatet aggregeras sedan till kommunnivå. 

Vattenkvalitet 

Parametern Vattenkvalitet säkerställer att konsumenten får en god vattenkvalitet. Kvaliteten bedöms utifrån tre 

kriterier, enligt Tabell 1. Gränsvärden som måste uppnås för att erhålla värderingen God, Otillräcklig eller Dålig 

status anges i Tabell 2. 

Det första kriteriet mäter andelen rutinprov, vilka tas på utgående vatten från vattenverket samt prov tagna ute på 

ledningsnätet, som bedömts som ’Tjänligt med anmärkning’. Rutinprover tas kontinuerligt och antalet prover som tas 

är reglerade i (SLVFS 2001:30) och beror på antal brukare. Provet bedöms enligt skalan tjänligt, tjänligt med 

anmärkning och otjänligt. I proven bedöms både vattenkvalitet samt mikrobiologisk förekomst. 

Det andra kriteriet säkerställer att rutinproven som bedömts som ’Tjänligt med anmärkning’ systematiskt följs 

upp och utreds. 

Det tredje kriteriet säkerställer att klagomål kring vattenkvaliten som lämnats av brukarna följs upp och utreds. 

Leveranssäkerhet 

Parametern Leveranssäkerhet visar om kommunen har tillräcklig säkerhet kring alternativa 

försörjningsmöjligheter. Parametern är uppdelad i två kriterier, enligt Tabell 1. Gränsvärden som måste uppnås för 

att erhålla värderingen God, Otillräcklig eller Dålig status anges i Tabell 2. 

Det första kriteriet mäter hur länge fullgod vattenkvalitet kan uppnås vid utnyttjande av tillgängligt reservvatten 

under en tidsperiod på 90 dagar. Reservvatten täcker in all tillgänglig nöd- och reservförsörjning exempelvis 

reservvattentäkter, tankbilar och paketerat vatten. 


Det andra kriteriet mäter hur länge brukarna kan försörjas vid ett utslaget vattenverk. 

Tabell 2 Benchmarkingmodellen med samtliga kriterier och gränsvärden. 

Värdering Kriterier samt gränsvärden 

Hälsomässigt säkert vatten: Brukarna har ett hälsomässigt säkert vatten 

God Hg1 24 h med vatten utan normal strömförsörjning 

genom reservkraft, tankbilar, reservoarvolym vid utslaget vattenverk. 

Otillräcklig Lo1 Alternativ försörjning kan upprätthållas utan fullgod vattenkvalitet i > 90 dagar. 

Lo2 Brukarna kan försörjas under > 12 h med vatten utan normal strömförsörjning 

genom t.ex. reservkraft, tankbilar, reservoarvolym vid utslaget vattenverk. 

Dålig Ld1 Alternativ försörjning kan upprätthållas utan fullgod vattenkvalitet i < 90 dagar. 

Ld2 

Brukarna kan försörjas under < 12 h med vatten utan normal strömförsörjning 

genom reservkraft, tankbilar, reservoarvolym vid utslaget vattenverk. 


Modellutvärdering 

Modellen har i ett första skede utvärderats för en liten och en stor kommun. Den större kommunen har två 

ytvattenverk vilka försörjer ca 500 000 invånare medan den mindre kommunen har 12 grundvattenverk vilka 

försörjer ca 20 000 invånare. Resultatet presenteras i Tabell 3. 

Tabell 3 Utvärdering av benchmarkingmodellen för två kommuner. 

Diskussion och slutsats 

Parameter Stor kommun Liten kommun 

Hälsomässigt säkert vatten Otillräcklig Dålig 

Vattenkvalitet God Dålig 

Leveranssäkerhet Dålig Dålig 

En första version av en benchmarkingmodell vilken utifrån ett konsumentperspektiv visar om en säker 

dricksvattenkvalitet uppnås inom en kommun har presenterats. Utvalda kriterier diskuteras kortfattat nedan. 

Gränsvärdet för kriteriet H1 anger andelen rutinprov med anmärkningen ’Otjänligt’ som får förekomma för att 

uppnå värderingen God. Det föreslagna gränsvärdet 1% otjänliga prov ger olika utfall beroende på storlek på 

kommunen, då antalet prover som tas baseras på antal brukare. En liten kommun som tar 100 prov eller färre 

kommer att nå över gränsvärdet 1% om de får ett enda otjänligt prov, medan en större kommun som tar fler än 100 

prov kan få flera otjänliga prov innan de når gränsvärdet på 1%. Ingen av kommunerna, Tabell 3, har uppmätt 

otjänliga prover, utan orsaken till att de inte uppnår värderingen God för parametern Hälsomässigt säkert vatten är 

att de inte uppfyller kriterium H3 fullt ut. 

Komplexiteten för den förenklade GDP:n bör varieras beroende på kommunstorlek och den bör kunna hantera 

både grundvattenverk och ytvattenverk. Man kan resonera kring om någon annan riskanalys ger motsvarande resultat 

som en genomförd GDP, exempelvis en Water Saftey Plan (WSP), Hazard Analysis and Critical Control Points 

(HACCP) eller Mikrobiologisk Risk Analys (MRA). Det är få vattenverk som genomfört en GDP och många verk 

kommer därför inte att uppnå värderingen God då benchmarkingmodellen tas i bruk. 

Det bör noteras att kommuner som kan tillhandahålla vatten med fullgod vattenkvalitet under en kortare period än 

90 dagar och sedan kan komplettera med vatten utan fullgod kvalitet under de resterande dagarna erhåller 

värderingen Otillräcklig för kriteriet L1. Det finns många möjliga scenarier som kan medföra att råvattentäkten 

förorenas eller att vattenverket inte kan leverera rent vatten till exempel genom en kontaminerad process på verket, 

förlorad kontroll av mikrobiologisk säkerhetsbarriär (kritisk styrpunkt), stora maskinhaverier, ledningshaveri inom 

anläggningen eller sabotage och olyckor inom vattentäkten. Kriterium L2 ska därför spegla hur länge brukarna kan 

försörjas vid ett utslaget vattenverk. 

En första version av en benchmarkingmodell utifrån ett konsumentperspektiv har presenterats i denna artikel. Den 

framtagna modellen visar övergripande om en säker dricksvattenkvalitet uppnås inom en kommun. Modellen är lätt 

att kommunicera till allmänheten och bör leda till att man inom kommunen reflekterar över varför man eventuellt 

inte uppfyller en säker dricksvattenkvalitet. 

Referenser 

Alegre, H., Baptista, J., Cabrera, E., Cubillo, F., Duarte, P., Hirner, W., Merkel, W. and Parena, R., Eds. (2010). Performance 

indicators for water supply services. 

Balmér, P. (2010). Benchmarking och nyckeltal vid avloppsreningsverk. Rapport nr 2010-10 Svenskt Vatten Utveckling. 

Norsk Vann (2011). Brukermanual for tilstandsvurdering. 

Vieira, P., Alegre, H., Rosa, M. J. and Lucas, H. (2008). "Drinking water treatment plant assessment through performance 

indicators." WST: Water Supply 8(3), 245-253. 

Norsk Vann (2009). Veiledning til bestemmelse av god desinfeksjonspraksis, Rapport nr 170-2009, ISBN 978-82-414-0307-1 



Session 2: Säker dricksvattenhantering 

Riskhantering i vattenförsörjningen 42 

Förbättrad SCADA-säkerhet vid 

dricksvattenanläggningar 47 

Hantering av känslig information 

inom dricksvattenförsörjningen 55 

QMRA som stöd i säkerhetsplaneringen 

– minskning och hantering av risk 

för norovirus via dricksvatten 58 

Kan klordioxid fungera som hygienisk 

barriär i interna distributionssystem? 62 

Samband mellan nederbörd uppströms 

ett dricksvattenverk och samtal till sjukvårds- 

upplysningen gällande mag-tarm symtom. 67 

VISK – Minskad risk för vattenburen smitta 

trots förändrat klimat 71 

Erfarenheter från workshopar om GDP och MRA 75 

NORVID projektet – analys av norovirus 

i dricksvatten 80 

Detektion av adenovirus i floden Glomma 85 

Ultrafilter – en oberoende mikrobiologisk barriär 86 

Modellering, övervakning och källspårning 

av mikrobiologiska risker i råvatten 94 

41

Risikostyring i vandforsyningen 

Corfitzen C B*, Arnbjerg-Nielsen K*, Andersen H S**, Jørgensen C**, Jacobsen P***, 

Mollerup F****, Lind S*****, Heidemann G ****** , Jensen R*******, Albrechtsen H-J* 

*DTU Miljø, Danmarks Tekniske Universitet, Miljøvej, bygning 113, DK-2800 Kgs. Lyngby, 

cbco@env.dtu.dk; karn@env.dtu.dk; hana@env.dtu.dk 

**DHI, Agern Allé 5, DK-2970 Hørsholm, hsa@dhigroup.com; clj@dhigroup.com 

***Århus Vand A/S, Bautavej 1, DK-8210 Århus V, pja@aarhusvand.dk 

****VandCenter Syd A/S, Vandværksvej 7, DK-5000 Odense C, fm@vandcenter.dk 

*****Københavns Energi A/S, Ørestads Boulevard 35, DK-2300 København S, soli@ke.dk 

******Naturstyrelsen, Haraldsgade 53, DK-2100 København Ø, guhei@nst.dk 

*******Odense Kommune, Flakhaven 2, DK-5000 Odense C, rij@odense.dk 

Abstract. Drinking water in Denmark is distributed with only few or no hygienic barriers between 

catchment and consumer, and it is therefore essential to monitor the drinking water quality. Traditionally, 

drinking water monitoring has been performed as a control of the delivered water quality rather than as a 

risk management, allowing to react timely on quality changes to prevent distribution of a deteriorated water 

quality. ‘From risk monitoring to risk management – risk assessment in water supply’ is a 3-year (2011- 

2013) innovation project under the strategic partnership ‘Water in Urban Areas’ (www.vandibyer.dk) carried 

out by the knowledge institutions DTU Environment, DHI, the water utilities Copenhagen Energy, Aarhus 

Water, VCS Denmark and the public authorities Odense municipality and the Danish Nature Agency. The 

purpose of the project is to develop and implement risk management as a part of the climate adaptation 

measures in the water supply. The risk management will be based on the development of a new and 

improved monitoring strategy from catchment to consumer - taking into consideration the possibilities and 

limitations of analytical methods and sensors - and the development and implementation of advanced 

quantitative risk analysis and management systems. The project work includes: a) Identification of focus 

areas based on experiences gathered from contamination cases in the involved water supplies; b) 

Identification of additional demand for management systems for monitoring based on experiences from the 

processes of implementing Water Safety Plans; c) Development of a new monitoring strategy; d) 

Development of quantitative risk assessment in water supply; e) Development of strategies for 

implementing extra hygienic barriers e.g. UV; f) Development of new software to cover identified demands 

for monitoring and management; g) Implementing and evaluating developed tools in demonstration 

projects, hereby ensuring further dissemination. The first part of the project has been a knowledge 

gathering based on the water utilities experiences from implementation of Water Safety Plans and from 

contamination cases. The knowledge gathering will be used to define monitoring strategies for the three 

scenarios a) the normal situation; b) a contamination situation; c) source tracking situation. 

Baggrund 

Vandforsyningen i Danmark er stærkt decentraliseret med over 2500 vandforsyninger og en årlig 

drikkevandsproduktion i størrelsesordenen 400 mio m 3 baseret udelukkende på grundvand. Efter en 

simpel behandling, der oftest kun består af iltning og sandfiltrering, distribueres drikkevandet uden 

desinfektionsresidual, og der er derfor ingen eller få hygiejniske barrierer mellem boring og forbruger. 

Monitering af drikkevandskvalitet bliver således essentiel. Historisk set bygger kvalitetssikring af 

vandforsyningsprocesser i langt højere grad på kontrol - det vil sige en måling af, om det leverede vand 

var i orden - end på styring, hvor der kan ageres ved ændring af vandkvaliteten så rettidigt, at distribution 

af forringet vandkvalitet hindres. Især på det mikrobiologiske område, hvor en vandanalyse kan tage 1-3 

døgn, er der behov for at kunne være mere på forkant. 

I forbindelse med de seneste års kraftige nedbørshændelser opstod der mikrobiologiske forureninger 

med efterfølgende kogeanbefaling i fx byerne Køge, Århus og København. Der er et udtalt behov for en 

forbedret overvågning af vandkvalitet i højdebeholdere og forsyningsnet, så risici ved øget 

nedbørsintensitet og efterfølgende oversvømmelse som konsekvens af klimaændring kan håndteres. 

42 Session 2: Säker dricksvattenförsörjning

Projektets formål 

Fra kontrol til styring – Risikovurdering i vandforsyningen er et tre-årigt (2011-2013) 

innovationsprojekt under det strategiske partnerskab Vand i Byer (www.vandibyer.dk). Projektgruppen 

består af vidensinstitutionerne DTU Miljø og DHI, vandforsyningerne Københavns Energi A/S, Århus 

Vand A/S og VandCenter Syd A/S samt de offentlige myndigheder Odense kommune og Naturstyrelsen. 

Projektet har til formål at udvikle og implementere risikostyring i vandforsyningen omfatter hele 

vandforsyningskæden – fra kilde, over vandbehandling, opbevaring og distribution til forbrugeren. 

Projektet vil således tage et skridt fra bagudrettet kontrol mod pro-aktiv styring af risici i forbindelse med 

levering af rent drikkevand. 

Risikostyring vil blive baseret på udvikling af nye og forbedrede moniteringsstrategier for 

vandforsyninger, på den nyeste teknologi (fx sensorer) og på udvikling og implementering af mere 

avancerede kvantitative risikoanalyser og kvalitetssikrings- og ledelsessystemer til sikring af vandets 

kvalitet, når det leveres til forbrugeren. Projektets aktiviteter inkluderer således: 

Identifikation af indsatsområder med hensyn til monitering baseret på erfaringsindsamling fra 

forureningssager hos de involverede vandforsyninger 

Identifikation af behov for styring baseret på moniteringen samt erfaringsopsamling fra 

implementeringen af kvalitetssikrings-/ledelsessystemer hos de i projektet involverede 

vandforsyninger 

Etablering af nye moniteringsstrategier – hvor skal der måles? for hvad? med hvilke 

metoder/sensorer? hvor ofte? for at opnå en strategisk optimal styring af risici fra kilde til forbruger 

Udvikling af kvantitativ risikovurdering i vandforsyningen 

Udvikling af strategier for placering af ekstra hygiejniske barrierer som fx UV-behandling i 

distributionssystemet baseret på fx ledningsnet modellering, risici og sårbare forbrugere 

Udvikling af værktøjer (software) der i videst muligt omfang dækker de identificerede behov for 

monitering og risikostyring, så de udviklede strategier kan gøres tilgængelige for andre 

vandforsyninger på en operationel måde 

Implementering og evaluering af de udviklede værktøjer i demonstrationsprojekter. Herved sikres, at 

de udviklede værktøjer testet i praksis, hvilket kan bidrage til efterfølgende udbredelse af de udviklede 

teknologier 

Erfaringsopsamlingen er gennemført i projektets første år, og denne danner grundlag for etableringen 

af moniteringsstrategier, der færdiggøres over sommeren 2012. 

Erfaringsopsamling 

Den danske miljøstyrelse gennemførte i 2004 et pilotprojekt, der skulle vurdere, om principperne fra 

ledelsessystemet ’Hazard analysis and critical control points (HACCP)’ – på dansk Risikofaktor analyse 

og kritiske styringspunkter – til fødevaresikkerhed var anvendelig i dansk vandforsyning: ”HACCP – et 

værktøj til risikostyring i vandforsyningen” (DANVA vejledning nr. 72) og DANVA nedsatte i 2004 et 

udvalg under Vandforsyningskomiteen til udarbejdelse af en vejledning for danske vandforsyninger om 

implementering af risikostyring efter HACCP principper støttet af Miljøstyrelsen: ”Vejledning i sikring af 

drikkevandskvalitet (Dokumenteret DrikkevandsSikkerhed - DDS) (Miljøprojekt 989, 2005). Disse to 

projekter anvendes som udgangspunkt ved indførelse af DDS i danske vandforsyninger. HACCP/DDS 

bygger på en gennemgang af processer og anlæg, risikovurdering og tiltag til forbedringer, hvor risikoen 

vurderes uacceptabel, hvorved styring af risici således er en af hjørnestenene. Det er i Danmark ikke et 

lovmæssigt krav, at en vandforsyning skal indføre DDS, og det estimeres, at kun omkring 10 

vandforsyninger har færdigimplementeret DDS, mens endnu 30-40 vandforsyninger estimeres at være i 

processen med at implementerer DDS. 

De tre vandforsyninger, der indgår i projektgruppen repræsenterer de største vandforsyninger i 

Danmark og udgør tilsammen ca. en femtedel af den samlede drikkevandsproduktion i Danmark. De har 

alle implementeret DDS (påbegyndt henholdsvis 2005, 2007 og 2008) og deltager regelmæssigt i 

forsknings- og udviklingsprojekter, hvorved de kan betragtes som ’first-movers’ indenfor branchen. På 

trods af implementering af DDS har vandforsyningerne oplevet forureningssager - inkluderende 

kogeanbefaling - indenfor de seneste år. Vandforsyningernes erfaringer fra implementering af DDS og 

Session 2: Säker dricksvattenförsörjning 43

oplevede forureningssager, vil således belyse områder, hvor DDS som værktøj kan forbedres, 

videreudvikles og tilpasses samt identificere risici og behov for yderligere monitering for at kunne styre 

disse risici. 

Erfaringsindsamlingen omfattede 

Indhentning og analyse af vandforsyningernes DDS dokumenter 

Interviews i vandforsyningerne om processen omkring implementering af DDS 

Interviews i vandforsyningerne om forureningssager 

Indsamling og analyse af data til udredning af udvalgte forureningssager 

Faglige diskussioner i projektgruppen ved projektmøder 

Hovedpointer fra erfaringsopsamlingen 

Erfaringsopsamlingen resulterede i en række elementer, der fødes ind i etablering af moniteringsstrategi. 

Af hovedpointer kan nævnes: 

Processen ved oprettelsen af de initiale DDS-dokumenter, og hvorledes de er implementeret i 

organisationerne varier hos de tre vandforsyninger, men hos alle tre er DDS forankret ved at blive en 

integreret del af ledelsessystemerne. Hos Københavns Energi A/S, der er den største af de tre 

vandforsyninger, har man desuden ansat en DDS koordinator, til at sikre den kontinuerlige forankring. Et 

essentielt element for en succesfuld implementering og forankringsproces er at motivere medarbejdere på 

alle niveauer i organisationen, og fastholde denne motivation ved at skabe en fælles ansvarsfølelse 

omkring DDS. Det er således vigtigt, at ledelsen melder ud, at DDS er en prioritering, og får tydeliggjort 

formålet og fornuften med de givne procedurer samt de resulterende konsekvenser/risici ved ikke at følge 

disse. Styring af risici afhænger i høj grad af, at der hos den enkelte medarbejder opnås forståelse for, at 

drikkevand er en fødevare, der kræver et højt hygiejneniveau. Det er lige væsentligt, at dette sker på 

ledelses/planlægningsniveau, som hos manden i marken, der rent faktisk arbejder med de åbne vandbaner. 

Udnævnelse af DDS-ambassadører på de forskellige niveauer i organisationen kan være et værktøj til 

dette. Forankringens succes vil dog forsat afhænge af, at DDS og hygiejne bliver en naturlig del af 

hverdagen, der kontinuert holdes opmærksomhed på fx ved at involvere medarbejdere i årlige 

introduktions- og genopfriskningskurser i DDS og hygiejne, gennemgang af specifikke cases, 

sidemandsoplæring, løbende interne og eksterne audits, og løbende opdatering af DDS dokumenter. Det 

er dog samtidig vigtigt, at der skabes åbenhed om indberetning af mangler og menneskelige fejl, der 

introducerer risici. Disse skal trygt kunne indberettes i en ikke-dømmende atmosfære uden konsekvenser 

for den enkelte medarbejder, så korrigerende aktioner kan foretages hurtigst mulig. 

Netop processen med specifikt at gennemgå egen vandforsyning og identificere risici og muligheder 

for styring gør DDS-dokumentationen unik for hver enkelt vandforsyning. Således er definitionen af 

sandsynlighed og konsekvens og den resulterende risiko (kategorisering som lav, mellem, alvorlig) 

individuel for de tre enkelte vandforsyninger, på trods af, at alle tre vandforsyninger har haft den samme 

konsulent tilknyttet arbejdet med at udarbejde de initiale DDS-dokumenter. 

Helt generelt for alle tre vandforsyninger vurderes relativt få identificerede risici som alvorlige under 

områderne ’Indvinding og Produktion’, dels på grund af at vandforsyningerne har relativt gode 

muligheder for styring i disse forsyningstrin, og mange konsekvenser vurderes lave på grund af stor 

fortynding. Det største antal identificerede risici vurderes alvorlige i området ’Distribution’, hvor antallet 

af risici for forurening er størst. End del risici vurderes som alvorlige under området ’Forbruger’, men 

dette er det forsyningstrin, hvor vandforsyningerne har mindst mulighed for styring, og oplysning af 

forbrugerne får stor betydning. Forskel på systemerne i de tre vandforsyningerne, variation i vurdering og 

de enkelte vandforsyningers mulighed for styring medfører, at en risiko identificeret i mere end én 

vandforsyning ikke nødvendigvis vurderes til samme kategori i alle tre vandforsyninger (eksempler i 

Tabel 1). 

Forældede anlæg og beholdere med dårligt design udpeges af vandforsyningerne som en særlig risiko, 

hvor, beholdere ofte er delvist bygget ind i terræn og har dårlig tilgængelighed, hvilket vanskeliggør 

tilstandsvurderinger. Utilstrækkeligt renoveringsbudget kan gøre det svært at eliminere risici forbundet 

med disse anlæg og beholdere, hvilket gør overvågning af risici meget vigtig. Er et anlæg eller beholder 

først kommet på renoveringslisten, er det nemt at glemme og overse de fortsat eksisterende risici indtil 

renoveringsprocessen reelt går i gang, og tiltag for at hindre dette bør tages. 


Tabel 1 Eksempler på vurdering af risici hos de tre vandforsyninger Århus Vand A/S (AAV), VandCenter 

Syd A/S (VCS) og Københavns Energi A/S (KE). Formulering af en given risiko i tabellen er ikke 

nødvendigvis ordret den samme i de forskellige vandforsyninger. Er en given vandforsyning ikke angivet 

ud for risiko, er risikoen ikke er specifikt identificeret i den enkelte vandforsyning. 

Risiko 

Indvinding 

Alvorlig Mellem Lav 

Indtrængen af kloakvand ved brud, infiltrering, 

utætheder 

AAV, KE VCS 

Indtrængen af overfladevand ved tilbagesug, brud, 

AAV, KE, 

utætheder, oversvømmelser 

Produktion 

VCS 

Dårligt vedligehold, dårligt/gammelt design AAV, KE VCS 

Manglende forståelse for processer og hygiejne 

(personale, håndværkere mf) 

AAV, KE VCS 

Trafik af personale, besøgende, håndværkere mm KE, VCS AAV 

(Forkerte) metoder til rengøring 

Distribution 

AAV, KE VCS 

Ikke muligt at ’stoppe vandet’ = spredning af 

forureningen 

AAV, KE, VCS 

Tilslutning af slamsuger til aftapningshane/brandhane AAV, KE VCS 

Forurening af ledningsnettet (fx overfladevand ved 

utætheder, brud, reparationer) 

KE, VCS AAV 

Krydskontaminering med kloakvand AAV, KE, VCS 

Overlevelse af patogener i ledningsnet (vanskelighed 

ved rengøring af nettet efter forurening) 

AAV, KE, VCS 

Adgang for fremmedlegemer og dyr ved uafproppede 

nye ledninger 

KE VCS 

Manglende forståelse for hygiejne og drikkevandssikkerhed 

AAV, KE VCS 

Manglende og sen tilbagemelding af fejl og afvigelser 

Forbruger 

AAV VCS 

Vækst af Legionella (og øvrige bakterier) i 

varmtvandssystemer 

AAV, KE, VCS 

Fejlagtig installationer/krydskontaminering med gråt 

spildevand/regnvand 

AAV, KE, VCS 

Tilslutning til højere anlægstryk end hvad kontraventil er 

beregnet til (udpumpning af forurening fra forbruger) 

KE, VCS 

Afgivelse af metaller fra installationer KE VCS AAV 

Det nuværende antal af sensorer i dansk vandforsyning er relativt begrænset. En opgørelse fra 2009 

(Corfitzen & Albrechtsen, 2011) af online-sensorparken i fem af Danmarks største vandforsyninger 

dækkende en fjerdedel af den samlede produktion (inklusiv projektgruppens tre vandforsyninger) viste, at 

når der anvendes online-sensorer på distributionsnettet er dette stort set udelukkende til måling af tryk, 

flow og temperatur i brønde. På vandværker var online-sensorer til turbiditet mest udbredt (15 værker), 

mens ilt blev målt online på 4 værker og pH samt ledningsevne på 2 værker. Disse sensorer var i de fleste 

tilfælde placeret ved afgang vandværk. I den mellemliggende periode er antallet af sensorer øget fordelt 

på flere vandværker, men der er forsat et relativt lille antal sensorer i dansk vandforsyning, og de er på 

vandværkerne oftest placeret på afgangen fra vandværket. 

En ting er at have sensorer installeret, en anden ting er bruge resultaterne. Både erfaringsopsamlingen i 

dette projekt og erfaringer fra Corfitzen & Albrechtsen (2011) viser et stort behov for værktøjer til at 

behandle og tolke de meget store datamængder fra online-sensorer og koble proxyparametre til 

kvalitetsparametre. Før vandforsyningerne har mulighed for aktivt at forstå og relatere informationen fra 

online sensorer til deres processer og distribution, vindes der ikke meget ved blot at foreslå flere sensorer 

opsat. 


En udfordring i dansk vandforsyning er desuden at identificere, hvilke parametre og sensorer, der kan 

bruges til overvågning af hvilke processer. Ved brug af fx overfladevand til drikkevandsproduktion vil 

proceskontrol kunne udføres ved overvågning af følgeparametre som fx farvetal, mikroalger, partikeltal, 

pH efter kemikaliedosering og desinfektionsresidual. Da der i Danmark anvendes grundvand og ikke 

desinficeres, er antallet af følgeparametre til proceskontrol stærkt begrænset. 

Alle tre vandforsyninger i projektgruppen tager i dag et langt større antal stikprøver end de lovpligtigt 

forskrevet. I denne sammenhæng skal prisen for et større antal prøver vægtes imod hvor meget ekstra 

information og sikkerhed, der opnås. Kriterierne for at fastlægge frekvens, antal og fordeling af stikprøver 

over distributionen for at opnå størst mulige forbrugersikkerhed og mulighed for styring udgør 

kerneelement i en moniteringsstrategi. I denne sammenhæng må også kriterier for det optimale prøvested 

fastlægges, fx at det skal være tilgængeligt på alle tider og ikke må kunne forurenes af en eventuel 

forbruger. 

Corfitzen et al. (2009) viste på baggrund af litteraturværdier for patogener i forureningskilder, at en 

coliform/100 mL kan repræsentere en sygdomsrisiko. Samtidig har Vang et al. (2011) vist, at 

indikatororganismerne kan overleve længe i drikkevandssystemer (uger), langt længere end patogener. 

Sammenfald imellem detektionsgrænse og grænseværdi for E. coli og coliforme stiller derfor 

vandforsyningerne i et dilemma om, hvordan der skal ageres på en periodisk opdukken af enkelte 

coliforme - repræsenterer de enkelte punktforureninger eller en lav kontinuert forurening. Efter en 

forureningssag er det ligeledes svært at skelne imellem en gammel forurening, der ikke er skyllet ud, og 

en vedvarende kontinuert forurening. Københavns Energi A/S har haft gode erfaringer med at bruge en 

døgnprøvetager, der kontinuert opsamler en delstrøm over et døgn til et filter, hvorved der over et døgn 

opnås en prøvestørrelse på fx 100 L, hvilket er en 1000 gange forøgelse af coliform / E. coli 

detektionsgrænsen. Derved opnås et mere nuanceret billede af fx et coliform-niveau. Brug af 

døgnprøvetager er ligeledes relevant i forbindelse med kildesporing, og var et væsentligt bidrag til daglig 

vurdering af, hvor kritisk situationen var under forureningssagen i Århus. 

Både til at forstå et vandforsyningssystem i normalsituationen, til at udarbejde et udbredelseskort ved 

forureninger og til at identificere omlægnings- og udskylningsmuligheder i forbindelse med 

forureningssager er der behov for ledningsnetmodeller, der kan belyse vandalder, flowretning, opblanding 

og tryk. Optimalt bør data fra online-sensorer kunne indgå som input til ledningsnetmodellerne. 

Funktionelle ledningsnetmodeller er yderst vigtigt værktøj i risikostyring, hvor det er afgørende, at 

modellerne er kalibrerede og afspejler den reelle virkelighed, fx at ventiler rent faktisk står, som de er 

indført i modellen. 

Næste skridt 

Erfaringsopsamlingen har gjort det klart, at risikostyring ikke opnås ved at fastlægge en universel 

moniteringsstrategi, men at man må arbejde med moniteringsstrategier for tre scenarier: 

Normalsituationen 

Forureningssituationen 

Kildesporing 

Disse scenarier har individuel fokus, som monitering og styringsværktøjer må tilrettelægges efter. 

Referencer 

Miljøprojekt 989 (2005) HACCP – et værktøj til risikostyring i vandforsyningen. Miljøstyrelsen 

DANVA vejledning nr. 72. Vejledning i sikring af drikkevandskvalitet (Dokumenteret DrikkevandsSikkerhed - 

DDS). DANVA 

Corfitzen, C.B.; Albrechtsen, H.-J. (2011) On-line kontinuert måling af drikkevandskvalietet. Naturstyrelsen 

(www,nst.dk), ISBN nr. 978-87-92708-29-8 

Vang, Ó.K.; Corfitzen, C.B.; Albrechtsen, H.-J.; Lindhardt, B. (2011) Overlevelse af indikatorbakterier og 

pathogener i ledningsnet. Naturstyrelsen (www.nst.dk) ISBN nr. 978-87-7279-240-8 

Corfitzen, C.B.; Vang, Ó. V.; Albrechtsen, H.-J. (2009) Risikovurdering og risikoprofil af forekomst af bakterier i 

drikkevand. Naturstyrelsen (www.nst.dk) ISBN nr. 978-87-92548-96-2 


Increased SCADA Security at Water Facilities 

- The need for improved technical and organizational awareness 

Ph.D. Erik Johansson 

Royal Institute of Technology (KTH), Dept. of Industrial Information and Control Systems, 

Osquldas väg 10, SE-100 44 Stockholm, Sweden, erik.johansson@ics.kth.se . 

Abstract. The supply of drinking water is largely dependent on maintaining the functionality of industrial 

control systems (also known as SCADA systems). Disturbances in SCADA systems for the production and 

distribution of drinking water are therefore indirectly a security risk. Not only to the water plant, but also to 

the society since water represents one of the populations’ most important provisions. Consequently, the 

Swedish Water and Wastewater Association (SWWA) and the Swedish Civil Contingencies Agency (MSB) 

supported a profound survey focused on SCADA security at Swedish drinking water suppliers. 

Findings from the survey confirmed that SCADA systems in the drinking water sector to a large extent are 

physically interconnected with administrative office networks. In several cases, SCADA systems have 

integrations not only to external stakeholders like SCADA system vendors but also to the Internet. This 

integration reduces overall security since SCADA systems are inherently vulnerable and not well protected 

against the increasing number of electronic threats from its environment. 

Since SCADA systems are increasingly exposed to threats they were not designed for, it is important to be 

aware of the many technical and organisational vulnerabilities that could impact their security and by 

extension their functionality.. 

The organisations ability to protect its SCADA systems and respond to different types of threats is a key 

issue for a reliable production and delivery of drinking water. 

However, the survey revealed that many drinking water organisations lack relevant security related 

procedures adapted to counter the vulnerabilities in SCADA systems. For instance, in order to perform 

appropriate risk and vulnerability analysis of SCADA systems, organisations need relevant security training 

and awareness of guidelines and standards. However, a vast majority of the respondents replied that there 

is a lack of necessary skills and knowledge about SCADA-security within their organisation. 

This paper highlights a number of findings from the survey and provides brief recommendations to mitigate 

weaknesses and increase security of SCADA systems in the drinking water sector. Furthermore, by calling 

attention to the need for further education and increased know-how regarding security in the drinking water 

sector, it will hopefully contribute to general SCADA security awareness. 

Keywords. SCADA, security, awareness, education, training. 


Introduction 

This section considers the general background and issues of SCADA security. 

Background 

Industrial information and control systems are widely used for control automation to enable services, 

quality and efficiency of water supply to the society. These industrial information and control systems are 

often denoted as SCADA systems (which is the abbreviation for Supervisory Control And Data 

Acquisition). SCADA systems still often use legacy technologies but have gradually, during the last 

decades, evolved and now use more modern computer-based systems (Cegrell 1994; Johansson 1996). 

Previously, SCADA systems have been relatively isolated. That is, stand-alone systems without 

connections to other systems or networks. However, with the advancements in microprocessor 

technologies, data could be multiplexed and collected from field stations and transmitted to a central 

location for supervisory control. Radio and leased phone lines were incorporated for communication 

between a central control room and field stations, resulting in the adoption of unattended monitoring and 

control capabilities for pump stations and water pipelines. 

Cost tends to be the primary motivational factor in modernizations of water utility plants. As a result, 

spending on IT systems and security tends to be relegated to the margins. As these plants began to 

automate from analog systems to digital control, they embraced "plug-n-play" systems to quickly 

interconnect remote and distributed sites over Internet Protocol (IP) because it was cheap and 

interoperable. In so doing, secure architecture wasn't a primary design consideration. In fact, the design of 

these SCADA systems did not really consider security at all (Johansson 1996; Johansson 2009; Krutz 

2006; Shephard 2002; Stamp 2003). 

The increasing use of computer-based components, and the integration with other IT systems has also 

affected the organisations staffing requirements. In several places, there are today fewer individuals that 

maintain the water supply to society than just a decade ago. One single operator can easily monitor and 

remotely control the waterworks pumps, valves and the entire water supply from a central workstation in 

a control room. And further development have now made it possible to move this workplace, it is not 

necessarily bound to a specific central control room, since applications exist to manage SCADA systems 

from mobile devices. 

Moreover, the computerization enabled the digitalization of other critical data, such as information 

about the location of pipelines and descriptions of systems and their configurations. This simplification of 

communicating data increases its availability to users and systems. However, this critical information is 

increasingly being sent across other networks, making it possible to reach data far beyond the local water 

companies' premises (Johansson 2007; Johansson 2009). 

Increased security concern 

Since many critical infrastructure services, such as water supply, depend on these SCADA systems, 

any vulnerability in them may result in undesirable consequences for citizens and society. In the light of 

the security breach that occurred more than ten years ago at Maroochy Water Services in Queensland, 

Australia, concern has thus been expressed regarding the security of SCADA systems (NIST 2008). 

Despite this concern, recent practical assessments implied that, information security is still weak when 

it comes to SCADA systems. One could approximate from these assessments that SCADA security is 

lagging roughly ten years behind traditional (office) IT-security. However, those findings might be 

anomalies and therefore not relevant to most of the water utilities in Sweden. 

In order to attain better understanding of the situation regarding information security at the drinking 

water sector in Sweden a more comprehensive survey of the SCADA environments and their security was 

initiated. This paper briefly illustrates and discusses the structure and general findings of this national 

survey. However, the paper will not go into any details of specific critical findings. 


The SCADA survey 

This section gives a short summary of purpose and method behind a survey that focused on SCADA 

security at Swedish drinking water suppliers. The Swedish Water and Wastewater Association (SWWA) 

together with the Swedish Civil Contingencies Agency (MSB) supported the survey. 

Purpose of the survey 

The main purpose of the survey was to highlight the current situation of information security related to 

the use of industrial information and control systems in production and distribution of drinking water. 

Therefore the survey focused on SCADA systems and typical activities relevant for security. 

The other more elusive yet important purpose was to increase the overall security awareness by getting 

organisations to discuss potential weaknesses while responding to the survey. The survey could introduce 

questions that the responding organisation never had been discussed or otherwise wouldn’t have brought 

up to attention. 

Structure of the survey 

The survey was conducted through a questionnaire that was distributed to all Swedish drinking water 

producers. The foundation for the questionnaire was based on experiences from previous practical 

assessments of SCADA security as well as existing national and international guidelines, standards and 

regulations (DOE 2003; DOE 2006; Fink 2006; ISO/IEC 2005; Johansson 2007; NISCC 2005;NIST 

2007; NFA 2003; NFA 2007; SEMA 2008; Stamp 2003). The work was also inspired by a similar study 

conducted in Holland on behalf of the Dutch National Cybercrime Infrastructure (NICC 2008). 

A large number of relevant issues emerged. Thus, the questionnaire became extensive and eventually 

included roughly 60 questions. The survey itself was structured into the following eight sections: 

1) Instructions to respondents – to inform about confidentiality. 

2) Reference model and terminology – to get common terminology. 

3) Background information – to get information about the respondent and their organization. 

4) Technical aspects of SCADA security. 

5) Organisational aspects of SCADA security. 

6) Threat and risk aspects of SCADA security. 

7) Other aspects – to get information about their dependence on external actors. 

8) Contact information – to be able to get further comments from respondents. 

In the introduction respondents were informed about the purpose and that the survey would be handled in 

a strictly confidential manner. 

Reference model of SCADA 

In order to explain the terminology used in the survey respondents were provided with a simple 

reference model, see figure 1 below. In the reference model four main areas were specified: the Operation 

centre’s computer network, the Process linked computer networks, the Administrative office computer 

network, and External computer network. 

Figure 1. The reference model to explain the overall environment of typical SCADA-systems. 


Note that in the survey (as well as in this paper), the expression SCADA is used as an overall term for 

all types of process control systems. Thus SCADA is mentioned in both operation centre’s computer 

network (the green cloud) and the production and distribution environment (the blue cloud). Other areas 

that often interact with SCADA systems are computer systems in the administrative office network (the 

yellow cloud), and computer systems from sub-contractors' services that are on the external network 

outside the organizations control (the red cloud), see figure 1 above. 

The survey, structured as a questionnaire, was sent out via letters to drinking water plants in Sweden. 

Together with the questionnaire a personal letter was included, describing the purpose and importance of 

the survey. One motivating factor for the respondents to invest time in this voluntary survey was that they 

in the long run could benefit from better support and guidance from SWWA. 

General findings 

Some general findings from the survey are briefly listed in this chapter. 

The response rate 

Six months after the survey was sent out 87 fulfilled answers had been received. Based on the background 

information given by respondents about their production, we could determine that the answers all together 

represented a production of more than 2 million cubic meters water per day. In relation to the total 

drinking water production in Sweden, this volume corresponds to a fairly high response rate, over 73 %. 

Aging organisations 

The survey had a couple of questions regarding the respondents’ background, experience and the size 

of their facility. These questions underlined the age profile of the respondents, see figure 2 below. 

Figure 2. The age profile of the respondents. 

The age profile indicates that there are competent and experienced staff on the water plants. However, 

large number of retirements in the future could reverse this age profile and cause problems unless plans 

are made to transfer knowledge from the employees who retire to their replacements (Johansson 2011). 

Absent isolation of SCADA systems 

A majority of SCADA systems in the drinking water sector was not isolated from other computerbased 

environments. Instead, they were increasingly being connected to administrative office networks 

and sometimes directly to the Internet. 

Dependence on external parties 

Findings indicate that knowledge in the security field is lacking. Only one out of four respondents 

believed that they had the necessary security skills within their organisation. This might explain the high 

degree of dependence on external parties (such as the vendors and system integrators). Only 12 % stated 

they were independent of other external parties to manage their SCADA environment. According to the 

survey a majority of respondents need increased support from the SWWA on how to manage information 

security for their SCADA-systems. 


Absent security policies and procedures 

The callow integration of SCADA systems might be related to the absence of well-established 

information policies and procedures regarding security. The survey indicates that SCADA systems are not 

really part of the regular risk and vulnerability analysis that is performed in the organisation, se figure 2. 

Figure 3. Only one quarter of the respondents include their SCADA-systems in business risk analysis. 

Use of default passwords 

Approximately 50 % of the respondents did not believe that there were default passwords, which could 

provide access to their system or equipment. Despite this, less than half said they had processes to change 

default passwords that have been set by the systems and infrastructure providers. 

Absent incident management 

Despite all vulnerabilities very few drinking water producers responded that they had been exposed to 

IT-related incidents. However, one explanation behind this might be that they probably would not even 

observe if an IT-related attack took place since they lack systems to monitor and detect intrusions. 

Furthermore, they lack business processes to systematically deal with subsequent incidents. Surprisingly 

few of the respondents had any management processes that described responsibilities if an IT-related 

incident were to occur. Thus, it might not be clear who is going to report to whom nor who is going to do 

what. 

Figure 4. A majority of the respondents did not have relevant incident management in place. 


Mitigations and proposal for further work 

In general, results from this survey corresponds to experiences from practical SCADA security 

assessments, i.e. the security is relatively weak in the water sector (Johansson 2007; Johansson 2009). 

The survey highlights several different weaknesses in areas that are important to security in SCADA 

systems. 

There are several things needed to mitigate the challenges to SCADA security that have been 

identified by this survey, for instance organisations should: 

• Increase security know-how and awareness by education and relevant training. 

• Identify misconfigurations in the infrastructure by mapping the network and its equipment. 

• Identify the critical assets that need to be protected. 

• Identify the vulnerabilities and the potential threats. 

• Ensure separation between networks by segmentation and topology hiding via firewalls. 

• Perform regular assessments and audits that include SCADA and external parties. 

• Monitor status of networks and equipment’s to determine visibility and changes. 

• Ensure that important equipment is being patched. 

• Introduce authentication and specify a strong password management. 

• Define clear roles and responsibilities regarding security. 

• Define and implement security policy and procedure that are suitable for the organization. For 

instance, practical procedures for how the organisation should handle removable media or how and 

when contractors may access any internal systems or networks. 

• Define and implement procedures for change management. 

• Define and implement procedures for incident management. 

• Introduce relevant security requirements in the procurement process. 

Maybe there is no “silver bullet”, i.e. there is no single straightforward solution that answers all the 

challenges mentioned above, but many of the mitigations listed above depend on the security awareness 

in the organisation. 

Proposals for further work 

The author would like to stress the importance to focus on increasing awareness and knowledge about 

SCADA security in the water sector and proposing further work in two areas, education and guidelines. 

Education and training 

To educate and increase the security awareness in the whole water sector is a long-term effort. The 

knowledge and awareness needs to be improved at all levels, among top managers as well as the 

operators/engineers. Several types of efforts needs to be made, such as practical assessments of SCADA 

systems, training and exercises on SCADA security, seminars/workshop arranged to discuss and share 

experiences of SCADA security, educational articles printed in industry publications or emails sent out 

with information regarding the actual threats and newly found weaknesses. 

Profound foundations for knowledge enhancement regarding SCADA security have been laid at FOI 

together with MSB. They have developed a two-day course on the security issues of SCADA and a 

mobile demonstration platform to enable on site customer training (FOI 2012). 

Checklists and guidelines 

Based on data from the survey SWWA have recently started work to develop a brief checklist that 

could assist organisations to identify weaknesses that could increase SCADA security in the drinking 

water sector. Besides additional checklists it is important to also develop practical guidelines that cover 

different aspects of security. For example, risk and vulnerability analysis, management of requirements 

during procurement, contract, monitoring and so forth. These checklists should correspond to current 

regulations, guidelines and standards in the field; see (ISO/IEC 2005; NFA 2008; SEMA 2008; SWWA 

2009; SWWA 2012). Existing advice and guidance needs to be regularly revised and adapted to technical 

and organisational needs. 


Summary 

This paper has given a brief summary of the survey on SCADA security performed in the Swedish 

drinking water sector. A survey that confirmed the warnings from earlier assessments regarding the weak 

security in SCADA systems in the drinking water sector. Besides the technical weaknesses of SCADA 

systems themselves the survey also reveal a general lack of security awareness in these organisations. 

It is important to remember the complication of SCADA systems that arises when one consider its 

environments. Three environmental factors impact security. Firstly, SCADA represent computer-based 

systems that if compromised can impact the physical water production/distribution and its equipment, 

which typically have safety concerns as well. Secondly, SCADA systems are highly vulnerable by nature, 

because by design they are command-and-control systems whose only purpose is to allow users to 

monitor and manipulate an automated process. In fact, current SCADA systems were never intended to be 

connected to the Internet, so they lack many of the security controls and features we see in modern office 

IT-systems. Thirdly, SCADA systems need to have high reliability, which is not always considered in 

traditional IT-security solutions. Despite these factors have SCADA systems have been increasingly 

integrated with office networks and sometimes even connected to the Internet. 

It is important for organisations to realise that there is often nothing that protect SCADA system if a 

valid username and password gets in the wrong hands. A SCADA system, like any other system, can only 

ever be as secure as those who use it. 

A kind of proof-of-concept intrusion was made in November 2011 by someone calling himself Pr0f. 

Pr0f posted proof that internet-connected SCADA systems controlling industrial equipment are easily 

accessible to unauthorized parties. He uploaded five pictures, what appears to be the human machine 

interface, controlling equipment used by South Houston's Water and Sewer (Register 2011), see figure 5. 

Figure 5. One of five images posted by 'pr0f' as a proof that internet-connected SCADA systems exist 

and are easily accessible to unauthorized parties (source: www.pastebin.com). 

However, with improved knowledge and increased security awareness, the water sector would be 

much better prepared and less likely to get undesirable IT-related incidents in the future. 


References 

Cegrell T. et al. (1994). “Industriella Styrsystem” (in Swedish), SIFU förlag, Borås, Sweden. 

DOE (2003). Office of Energy Assurance, 21 Steps to Improve Cyber Security of SCADA Networks, U.S. 

Department of Energy, USA. 

DOE (2006). Office of Energy Assurance, Roadmap to Secure Control Systems in the Energy Sector, U.S. 

Department of Energy, USA. 

Fink, R. et al. (2006). Lessons Learned From Cyber Security Assessments of SCADA and Energy Management 

Systems, U.S Department of Energy, USA. 

FOI (2012). “Säkerhet i industriella kontrollsystem (SIK)” (in Swedish), Swedish Defence Research Agency (FOI), 

Internet: http://www.foi.se/sik 

ISO/IEC (2005), ISO/IEC 27002:2005 Information technology - Security techniques - Code of practice for 

information security management, International Organization for Standardization (ISO). 

Johansson, E. (1996). Safety-Critical Control Systems - The challenge of migrating from hardware to software, 

Licentiate Thesis, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, Sweden. 

Johansson E. (2005). Assessment of Enterprise Information Security – How to make it Credible and efficient, 

PhD Thesis, School of Electrical Engineering, The Royal Institute of Technology (KTH), Stockholm, Sweden. 

Johansson, E. et al. (2007). “Aspekter på antagonistiska hot mot SCADA-system i samhällsviktiga verksamheter”, 

(in Swedish), Swedish Emergency Management Agency (SEMA), Sweden. 

Johansson, E. et al. (2009). Practical Security Assessment of SCADA-systems - Experiences from a drinking water 

facility, the American Water Works Association (AWWA) Annual Conference and Exposition, San Diego, USA. 

Johansson, E. (2011). Survey on Scada Security in Swedish Drinking Water Supply, Report C 29-120 (in Swedish), 

the Swedish Water and Wastewater Association (SWWA), Sweden. 

Krutz, R., (2006). Securing SCADA Systems, Wiley Publishing, Indianapolis, Indiana, USA. 

NICC (2008). SCADA Security Good Practices for the Drinking Water Sector, Report TNO-DV 2008 C096, TNO 

Defense, Security and Safety, The Netherlands. 

NISCC (2005). Good Practice Guide on Firewall Deployment for SCADA and Process Control Networks, National 

Infrastructure Security Coordination Centre, London, UK. 

NIST (2007) Guide to Industrial Control Systems (ICS) Security, Special Publication 800-82, National Institute of 

Standards and Technology (NIST), Gaithersburg, USA. 

NIST (2008) Malicious Control System Cyber Security Attack Case Study-Maroochy Water Services, Australia, 

National Institute of Standards and Technology (NIST), Gaithersburg, USA. 

NFA (2003). “Handledning för ökad IT-säkerhet inom dricksvattenområdet” (in Swedish), Report 4-2003, The 

National Food Agency (NFA), Sweden. 

NFA (2007). “Säkerhetshandbok för dricksvattenproducenter” (in Swedish), The National Food Agency (NFA) and 

the Swedish Water and Wastewater Association (SWWA), Sweden. 

SEMA (2008). ”Guide to Increased Security in Process Control Systems for Critical Societal Functions”, The 

Swedish forum for information sharing concerning information security – SCADA and process control systems 

(FIDI-SC), Swedish Emergency Management Agency (SEMA), Sweden. 

Shaw, W. T. (2006). Cybersecurity for SCADA systems. PennWell Corp, USA. 

Shephard, B. (2002). Information security - Who cares? Proceedings of Fifth International Conference on Power 

System Management and Control, London, UK. 

Stamp J. et al. (2003), Common Vulnerabilities in Critical Infrastructure Control Systems, Sandia National 

Laboratories Report 1772C, USA. 

SWWA (2009), “Säkerhet i IT-system” (in Swedish), the Swedish Water and Wastewater Association (SWWA) 

Electronically available: 

SWWA (2012), Updated “Säkerhetshandbok för dricksvattenproducenter” (in Swedish), The National Food Agency 

(NFA) and the Swedish Water and Wastewater Association (SWWA), Sweden. 

Register (2011), Second water utility reportedly hit by hack attack, San Francisco, USA. Article electronically 

available: 


Hantering av skyddsvärd information inom 

dricksvattenförsörjningen 

Ann-Sofie Wikström* 

* Vatten & Miljöbyrån, Bergvikskurvan 11C, 973 31 Luleå, ann-sofie.wikstrom@vmbyran.se 

Abstract. Drinking water supply is of essential importance for a community. Hence, it is defined as an 

important public function. Information handled on daily basis within the water supply management can, if in 

wrong hands, harm the water supply and therefore cause considerable damage on the community. The 

information may concern operational data, management, location and design of installations, emergency 

plans et c. Thus, it is important to consider how to handle the information. 

Also, security risks have to be considered if a person or an organisation gather non-classified information 

in order to combine it for inappropriate use. Separate, non-sensitive pieces of information may obtain a 

completely different importance when combined. 

Since the public, according to the Freedom of the Press Regulation, has the right to access public 

documents, it is important to make sure that sensitive information is classified in an appropriate way to 

avoid jeopardising the security of the water supply systems by giving away information too easily. 

The main laws where legal support for protecting information is given are the Principle of Public and 

Privacy Act (2009:400, Offentlighets- och sekretesslagen) and the Security Act (1996:627, 

Säkerhetsskyddslagen). 

The national organisation Swedish Water has issued a guideline on how to handle sensitive information 

within the water supply management. The guideline mainly addresses the responsible authorities within 

the municipal water supply management. 

Abstract. Vattenförsörjningen är en viktig hörnsten i ett väl fungerande samhälle och definieras därmed 

som en samhällsviktig funktion. Inom verksamheten produceras och hanteras dagligen uppgifter som i 

orätta händer kan skada dricksvattenförsörjningen och därigenom ge upphov till stor skada i samhället. 

Informationen kan omfatta uppgifter om lägen, utformning, drift och funktion av vitala anläggningsdelar 

samt sårbarhetsanalyser, skyddsåtgärder och beredskapsplaner. Det är därför viktigt att tänka över hur 

dessa uppgifter ska hanteras. 

Man måste även beakta den säkerhetsrisk som föreligger när information, som i sin enskilda form inte är 

skyddsvärd, samlas in och sammanställs av en aktör med mål att använda den nya informationen för 

otillbörliga syften. En sådan informationsinsamling kan innebära att uppgifter som i sin enskilda form inte 

är skyddsvärda får ett helt annat värde. 

Eftersom allmänheten enligt Tryckfrihetsförordningen har rätt att ta del av offentliga handlingar är det 

viktigt att se över skyddsbehovet för uppgifter kopplade till vattenförsörjningen för att säkerställa att känslig 

information inte hamnar i orätta händer. Det är främst Offentlighets- och sekretesslagen (OSL) 2009:400 

och Säkerhetsskyddslagen 1996:627 som ger lagstöd till skydd för uppgifter. 

Som ett stöd hur skyddsvärda uppgifter ska hanteras har Svenskt Vatten tagit fram Råd och riktlinjer för 

hantering av skyddsvärda uppgifter inom dricksvattenförsörjningen, i första hand avsedda för huvudmän 

inom kommunal vattenförsörjning. 

Bakgrund 

Under de senaste åren har vid några tillfällen privatpersoner krävt att få tillgång till uppgifter kring 

vattenförsörjningen som berörda kommuner och VA-bolag inte ansett lämpligt att lämna ut på grund av 

att uppgifterna anses känsliga. Enligt Tryckfrihetsförordningen, som är en av Sveriges grundlagar, har 


vem som helst rätt att ta del av en offentlig handling. Verksamhetsutövaren har inte rätt att efterforska 

varför personen vill ha vissa handlingar eller vad han eller hon heter eller ska ha handlingarna till. 

För att skyddsvärd information inte ska hamna i orätta händer är det viktigt att se över skyddsbehovet 

vid all hantering av uppgifter kopplat till dricksvattenförsörjningen. Det är främst Offentlighets- och 

sekretesslagen (OSL) 2009:400 och Säkerhetsskyddslagen 1996:627 som ger lagstöd till skydd för 

uppgifter. 

Offentlighets- och sekretesslagen innehåller bestämmelser om när en uppgift omfattas av sekretess. Av 

säkerhetsskyddslagen framgår hur skyddsvärda uppgifter som blivit sekretessbelagda ska skyddas. 

Råd och riktlinjer 

Svenskt Vatten har på initiativ av Norrvatten och Sydvatten tagit fram Råd och riktlinjer för 

hantering av skyddsvärda uppgifter inom dricksvattenförsörjningen som syftar till att ge konkreta 

råd hur skyddsvärda uppgifter ska hanteras och hur sådana uppgifter kan sekretessbeläggas. Vatten & 

Miljöbyrån har fungerat som projektledare och tillsammans med konsultföretaget Ekelöw ansvarat för 

utformningen och författandet. I projektet har även Livsmedelsverket och Myndigheten för 

samhällsskydd och beredskap (MSB) medverkat. 

Sekretessbedömning 

Redan när en handling upprättas ska samtidigt en metodisk sekretessbedömning av handlingens 

innehåll genomföras med hänvisning till offentlighets- och sekretesslagen. Det räcker alltså inte att göra 

en sekretessbedömning av handlingens innehåll i samband med en begäran om utlämnande av aktuell 

handling. Sekretessbedömningen ska göras av den som upprättar handlingen eller har handlingen i sin 

vård. 

Det första steget är att identifiera vilken typ av information som är skyddsvärd. Därefter görs en 

sekretessbedömning av handlingens innehåll. Slutligen upprättas rutiner för hantering av sekretessbelagda 

handlingar. 

Nedanstående lista ger en fingervisning om vilken typ av information som eventuellt kan vara 

skyddsvärd. En sekretessbedömning måste dock göras i varje enskilt fall av innehållet i den handling som 

ska sekretessbeläggas. Det är inte tillåtet att generellt stämpla en handling med sekretess utan konkreta 

grunder. Bedömningen kan påverkas av anläggningarnas storlek och om det finns speciellt sårbara eller 

”viktiga” abonnenter anslutna till den specifika anläggningen. 

Uppgifter som eventuellt kan bedömas som skyddsvärda: 

• Beskrivning av vitala delar i vattenförsörjningssystem (läge och utformning) 

• Uppgifter angående drift av vitala anläggningsdelar 

• Vitala anläggningars kapacitet, funktion och roll 

• Risk- och sårbarhetsanalyser, säkerhetsanalyser, förmågebedömningar, beredskapsplaner 

• Skyddsåtgärder (skalskydd, larm, bevakningsåtgärder) 

• Säkerhet kring styr- och övervakningssystem 

Om en handling delvis innehåller sekretessbelagda uppgifter täcks dessa över. Resterande del är 

offentlig och ska därmed lämnas ut. En övertäckning kan göras genom att man på en kopia av originalet 

stryker över de sekretessbelagda uppgifterna med en svart penna. 


Lagstöd 

I Råd och riktlinjer för hantering av skyddsvärda uppgifter inom dricksvattenförsörjningen listas 

exempel på handlingar och uppgifter inom dricksvattenförsörjningen som kan innehålla skyddsvärda 

uppgifter och därmed eventuellt kan sekretessbeläggas. Av förteckningen framgår även vilken eller vilka 

paragrafer i offentlighets- och sekretesslagen som kan användas som stöd i sekretessbedömningen. Det är 

dock inte möjligt att generellt hänvisa till ett visst lagrum i offentlighets- och sekretesslagen, varje uppgift 

och handling måste hanteras specifikt utifrån förutsättningarna i den egna verksamheten. Det måste ske en 

noggrann analys och övervägande av de skyddsvärda uppgifterna i varje enskilt fall innan uppgifterna kan 

sekretessbeläggas. 

I de flesta fall gäller offentlighet för uppgiften, vilket innebär att en uppgift kan sekretessbeläggas 

endast under förutsättning att ett röjande av uppgiften kan leda till men eller skada som framgår av 

bestämmelsen i offentlighets- och sekretesslagen. 

Det finns prejudikat där ett överklagande av sekretess prövats i Regeringsrätten (Regeringsrättens dom 

4508-1988), som slog fast att uppgifter om dricksvattenförsörjningen i den kommunala beredskapsplanen 

inte skulle lämnas ut till en privatperson. Det räckte att skadan var antaglig för att hemlighålla uppgiften. 

Det som är avgörande för hur rätten kommer att ställa sig är hur väl man kan motivera den skada man 

kan anta uppstår i händelse av att uppgifterna lämnas ut. Därför är det viktigt att det finns ett väl 

dokumenterat underlag för de beslut som fattas i samband med att en uppgift sekretessbeläggs. En 

riskanalys bör ingå som en del av denna dokumentation. 

Tips på vägen 

• Gör en bedömning av skyddsbehovet redan vid framtagande av uppgifterna – det är för sent 

när någon frågar! 

• Tänk på att information som i sin enskilda form inte är skyddsvärd, i samlad form kan få ett helt 

annat värde och därmed utgöra en risk. 

• Begränsa tillgängligheten, lägg inte slentrianmässigt ut information på intranät och gemensamma 

servrar med åtkomst för alla. Risken för en okontrollerad spridning av känsliga uppgifter ökar 

med ett ökat antal personer som förfogar över uppgifterna. 

• Upprätta rutiner för hantering av känsliga uppgifter, såväl internt som externt 

• Ställ krav och teckna sekretessavtal med externa konsulter, entreprenörer och leverantörer 

(support) av programvaror 


QMRA to support Water Safety Planning: mitigation and 

management of norovirus risks via drinking water 

Susan R. Petterson*, Arve Heistad*, Razak Seidu*, Thor Axel Stenström* and Jakob R. 

Ottoson ** 

* School of Mathematical Sciences and Technology, Norwegian University of Life Scinces, Ås, Norway, 

c/P.O. Box 1, Parramatta, Australia susan.petterson@umb.no 

** Sveriges lantbruksuniversitet och Statens veterinärmedicinska anstalt, Box 7028, 75007 Uppsala, 

jakob.ottoson@slu.se 

Abstract. A quantitative microbial risk assessment (QMRA) was undertaken for Nedre Rommerike 

Vannverk (NRV), using water from the Glomma River, taking into consideration failure events in water 

treatment. Before data on virus loads in the river are available norovirus concentrations in the source water 

was modelled from historical data on faecal indicators (E. coli and Clostridium perfringens) in the river and 

assuming a single faecal source ( raw or treated sewage). Results from this initial assessment indicate that 

NRV can supply safe water under expected (normal) conditions but is vulnerable to disinfection 

(chlorination) failure. Future data from the VISK project on source water quality and virus treatment 

removal will improve the risk models further enabling assessment of future events such as increased river 

flow as a consequence of climate change. 

Introduction 

An objective of the EU-VISK project is to apply the principles of water safety planning to assess, and 

provide recommendations for the mitigation and management of the risk of norovirus infection (via 

drinking water) in the Nordic region. Quantitative Microbial Risk Assessment (QMRA) has been shown 

to be a valuable tool in many aspects of the application of WSPs (Medema et al. 2006) including: system 

assessment (evaluation of whether the system is able to supply safe drinking water); monitoring 

(identification of critical limits for critical control points) and management (development of effective 

management strategies focused on system vulnerabilities). This study presents the first results from one of 

two planned project case studies: the Glomma River, Norway. 

Method 

Nedre Rommerike Vannverk (NRV) draws water from the Glomma River at Sørumsand, Norway which 

is then treated by conventional treatment, granular activated carbon and free chlorine disinfection before 

distribution to around 140,000 people. Norovirus exposure was calculated by determine virus 

concentration at NRV source water offtake and further virus reduction in the treatment plant as described. 

Source Water Concentration: The first step in the exposure assessment was to quantify the norovirus 

concentration (expressed as viral units per liter (vu.L -1 )) in raw water. The concentration was quantified 

by: fistly intial review of faecal indicator concentration in raw water: a gamma distribution was fitted to 

the reported E. coli (n=505) and Clostridium perfringens (n=271) concentrations from samples collected 

between 1999 and 2012 from the raw water intake to describe the variability in indicator concentration. 

Secondly, modelling of norovirus concentration in raw and treated sewage at the two closest sewage 

treatment plants (Rånåfoss and Fjellfoten) upstream of the offtake on the Glomma River. The 

concentration was predicted using the following formula: C=(N×d×l)/q where C was the concentration 

of norovirus in raw sewage (vu.L -1 ); N was the number of people excreting norovirus; d was the density 

of norovirus in the faeces of infected individuals (vu.g -1 ); l was the faecal load per person per day (150g); 

and q was the average daily flow to the treatment plant. N was assumed to follow a binomial distribution 

with probability equal to the point prevalence (for infection), and the number of trials equal to the 

population serviced by the treatment. Input values used in the modelling are summarised in Table 1. 

Thirdly, the faecal indicator concentration and the norovirus concentration in raw and treated sewage 

were used to predict the norovirus concentration at the raw water offtake. When only a single faecal 


source is assumed (either Rånåfoss OR Fjellfoten,; either raw OR treated ) the raw water concentration 

can be predicted using the ratio of indicators in raw water:indicators in sewage as a concentration 

reduction factor. Using this factor assumes that the environmental dispersion and inactivation norovirus is 

the same as the indicator organism. The model was implemented under the assumption of either Rånåfoss 

OR Fjellfoten (Raw or treated) as the faecal source, using either E. coli or Clostridium perfringens as the 

indicator organism for the ratio. 

Table 1 Model input values for predicting norovirus concentration in sewage 

Parameter Rånåfoss Fjellfoten 

Population (2011) 13195 592 

Average daily flow (m 3 .day -1 ) 2812 192 

C. perfringens E. coli Norovirus 

Point Prevalence a 

0.22 0.95 1.53×10 -3 

Excretion density (d) vu.g -1 

10 6.5 

10 8.0 

10 7.5 

Sewage treatment performance b (Log10) 2 3.5 1 

a 

Point prevalence for norovirus was the average of calculated values based on weekly reported incidence of 

norovirus in Sweden 2010 (SMI online data, 2010), corrected for underreporting (factor = 38); asymptomatic 

cases (30%); duration of excretion per case = 14 days. b (Ottoson et al. 2006) 

Treatment: The performance of the treatment train was evaluated under expected and sub-optimal 

operation conditions. Expected performance conditions: In the absence of local data the expected 

removal performance of each of the treatment barriers was evaluated based on reported values in the 

literature: Coagulation/Sedimentation/Rapid Sand Filtration: Hjinen and Medema (2007) undertook a 

meta-analysis and reviewed seven studies of virus removal by conventional treatment. Reported removal 

rates varied between 1.2 and 5.3 with a weighted average of 3.0 Log10 removal. Granular Activated 

Carbon: No removal was assumed to be achieved by GAC filtration (Hijnen et al. 2010). Free Chlorine 

Disinfection: The method presented by Petterson et al (2010) for quantifying virus reduction by chlorine 

disinfection was applied. For regulatory reasons the treatment plant must achieve a 0.05 mg. L -1 free 

chlorine residual after 30 minutes residence time. Dosing varies to achieve this target, but is in the range 

of 0.1 mg.L -1 . In the absence of local hydraulic data the reactor was assumed to behave as six CSTR s in 

series. Sub-optimal performance events: the impact of both coagulation and chemical dosing failures 

were evaluated. Coagulation failure: the removal of viruses by conventional treatment is strongly 

dependent upon coagulation performance. Failure of either coagulant (PAX or Polymer) was assumed to 

lead to no removal of viruses by conventional treatment. Filter breakthrough: Pathogen breakthrough of 

filters can occur, particularly at the beginning and the end of the filter cycle. When coagulation is 

performing adequately, filter breakthrough was assumed to reduce the virus reduction from 3.0 Log10 to 

1.2 Log10 (the lower range of reported removal rates in the literature). Chlorine failure: Failure of chlorine 

dosing was assumed to lead to no inactivation by disinfection 

Risk modelling: To explore the impact of the above assumptions, the risk model was run for several 

assumptions using the following inputs. Exposure volume: LogNormal distribution (Westrell, 2006) 

Dose-response model: Exact Beta-Poisson model (••=0.04, ••=0.055) (Teunis et al. 2008) Annual 

Infection: Annual infection was calculated from the infection risk (Pinf) and is given by Pann= 1-(1-Pinf) 365 

DALY weighting per infection: 7.16 × 10 -4 (Petterson et al. 2010). Scenario Analysis: Source water 

concentration estimates for risk simulations were based on assuming sewage was sourced from Rånåfoss 

or Fjellfoten, and using E. coli as the indicator (since it provided similar, and conservative results in 

comparison to C. perfringens based estimates). The following risk scenarios were modelled: 1.Expected 

removal to determine if the system is able to supply safe water, able to meet the health target of 1 ×10 -6 

DALY per person per year; 2. Coagulation failure, and determination of the required chlorine dose to 

achieve the health target during a coagulation failure event; 3. Filtration failure of one and three parallel 

lines.; and 4. Chlorination failure 


Results 

Source water quantification: The gamma distributions fitted to the reported E. coli and Clostridium 

perfringens concentrations are illustrated in Figure 1a. The mean (upper 95 percentile) of concentration 

was 395 (1687) org.L -1 and 60 (237) org..L -1 for E. coli and Clostridium perfringens respectively. The 

modelled cumulative distribution of nororvirus concentrations in raw sewage at Rånåfoss and Fjellfoten 

wastewater treatment plants is illustrated in Figure 1b. At Rånåfoss there is a high probability of zero 

concentration (~55%) which is due to the low prevalence and the small population (592), resulting in a 

lower probability of one or more excreters in comparison to the larger treatment plant at Fjellfoten. The 

modelled peak concentration at each treatment plant is similar and greater than 10 000 vu.L -1 . 

Figure 1 a) (left) Gamma distributions fitted to reported concentrations from samples analysed at the raw 

water intake to Nedre Rommerike Vannverk (zero values replaced with half the detection limit) b) (right) 

Modelled norovirus concentration in raw sewage at Rånåfoss and Fjellfoten sewage treatment plants 

The modelled cumulative distribution of norovirus concentrations at the raw water intake, based on the 

faecal indicator concentration and the sewage treatment plants as assumed sources are illustrated in 

Figure 2. The predicted concentration was much higher when the faecal source was assumed to be 

secondary treated effluent in comparison to raw sewage, since noroviruses were assumed to be poorly 

removed during sewage treatment in comparison to E. coli and C. perfringens. 

Risk simulations: The results of the risk simulations are reported in Table 2. The overall expected 

performance of the treatment train from literature estimates for norovirus was 8.5 Log10 which was 

adequate to achieve the 1× 10 -6 DALY; indicating that under expected conditions the systems is able to 

supply safe water. Under the assumptions of the model, coagulation failure led to a 3 Log10 increase in 

risk which could be reduced to below the health target by doubling the chlorine dosage. Filtration 

breakthrough had a relatively minor influence on the risk with chlorine failure being the most significant 

modelled failure event. 

Table 2 Results of risk simulations DALYs per person per annum 

Assumed source of faecal contamination 

(based on E. coli results) 

Rånåfoss Fjellfoten 

Mean 95% Mean 95% 

Source water concentration (vu.L -1 ) 62 475 63 440 

Expected performance (DALY) 1.4× 10 -8 

1.1× 10 -7 

1.4×10 -8 

1.0×10 -7 

Coagulation failure (DALY) 1.4× 10 -5 

1.1× 10 -4 

1.4×10 -5 

9.3×10 -5 

Coagulation failure + chlorine dosing 

@0.2mg.L -1 (DALY) 

3.7× 10 -7 

2.8× 10 -6 

3.8× 10 -7 

2.6× 10 -6 

Filtration (1 filter failing) (DALY) 1.2× 10 -7 

9.4× 10 -7 

1.3×10 -7 

8.7×10 -7 

Filtration (3 filter failing) (DALY) 3.4× 10 -7 

2.6× 10 -6 

3.5×10 -7 

2.4×10 -6 

Chlorination failure* (DALY) 7.2× 10 -4 

7.2× 10 -4 

7.2× 10 -4 

7.2× 10 -4 

*Risk of one or more infection per year = 1 


Figure 2 Modelled norovirus concentration at the raw water intake to the Nedre Rommerick Waterworks 

based on the measured faecal indicators concentration (E. coli, C. perfringens) and assuming a single 

faecal source: either Rånåfoss or Fjellfoten sewage treatment plants 

Discussion 

QMRA provides a useful approach for exploring risk factors within the water safety planning framework. 

Different faecal sources and treatment events have been modelled and prioritised. The modelled norovirus 

concentrations were strongly dependent upon the assumed source material: firstly whether it was raw or 

treated sewage (which led to ~ 2 Log10 difference in the predicted concentration) and secondly, the size of 

the population contributing to the treatment plant. This initial study has highlighted where additional data 

is needed including enumeration of noroviruses in sewage at each of the treatment plants; and at the raw 

water intake for comparison with the modelled values; and treatment performance quantification. 

Treatment failures or sub-optimal performance can lead to important fluctuations in risk, the likelihood 

and consequences of which need more detailed information on failure frequencies, durations and 

consequences. The treatment train at NRV is heavily dependent upon chlorination and more data is 

needed on the sensitivity of norovirus to chlorine in Nordic waters including the influence of organic 

matter on norovirus inactivation. These important factors have not yet been accounted for and a new 

simulation will take place this autumn when more data from VISK work packages 3, virus load in source 

water, and 4, virus reduction, are available. 

References 

Hijnen, W. A. and Medema, G. (2007). Elimination of micro-organisms by water treatment processes, 

KWR Watercycle Research Institute. 

Hijnen, W. A., Suylen, G. M. H., Bahlman, J. A., Brouwer-Hanzens, A. and Medema, G. J. (2010). GAC 

adsorption filters as barriers for viruses, bacteria and protozoan (oo)cysts in water treatment. 

Water research 44, 1224-1234. 

Medema, G., Loret, J.-C., Stenström, T. A. and Ashbolt, N. (2006). Quantitative Microbial Risk 

Assessment in the Water Safety Plan. Final Report on the EU MicroRisk Project. Brussels, 

European Commission. 

Ottoson, J., Hansen, A., Bjo¨rlenius, B., Norder, H. and Stenstro¨m, T. A. (2006). Removal of viruses, 

parasitic protozoa and microbial indicators in conventional and membrane processes in a 

wastewater pilot plant. Water Research 40, 1449-1457. 

Petterson, S., Grellier, J., Stenström, T., Meriläinen, P., Bucchini, L. and Nieuwenhuijsen, M. (2010). 

Development of a software tool for undertaking comparative risk assessment of DBPs and 

pathogens in drinking water Final report on risk/benefit analysis for the EU HiWATE Project. 

Brussels, European Commission. 

Teunis, P. F. M., Moe, C. L., Liu, P., Miller, S. E., Lindesmith, L., Barie, R. S., Pendu, J. L. and Calderon, R. L. 

(2008). "Norwalk Virus: How Infectious is It?" Journal of Medical Virology 80, 1468-1476. 


Chlorine dioxide as a hygienic barrier 

Ingun Tryland*, Aina Charlotte Wenneberg** and Helge Liltved*** 

Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, *Ingun.Tryland@niva.no 

**Aina.Charlotte.Wenneberg@niva.no *** Helge.Liltved@niva.no 

Abstract. Drinking water- and sewer pipes are often located in the same ditch. Under special conditions, 

including leakages and under-pressure in the drinking water pipes, intrusion of sewage contaminated 

water to the drinking water pipes may occur. This may have negative consequences, in particular for 

vulnerable consumers. Recently, there has been an increasing interest of using chlorine dioxide for 

controlling Legionella growth in e. g. hospitals- or hotels internal drinking water systems. The aim of the 

presented paper was to investigate to what extent chlorine dioxide, used under conditions simulating 

internal distribution systems operated to control Legionella growth, was able to inactivate faecal indicator 

bacteria added to the drinking water. In laboratory experiments, using tap water from the city of Oslo at 

temperatures of 5 and 20 °C, sewage was added to the tap water in dilutions from 1:10 to 1:500 for 

simulating contamination of drinking water during distribution. Disinfection experiments were performed by 

adding 0.1-0.5 mg/l chlorine dioxide for a contact time of 2.5, 5 or 7.5 minutes, for mimicking disinfection in 

internal distribution systems. The chlorine dioxide residual and the inactivation of Escherichia coli, total 

coliforms, intestinal enterococci and Clostridium perfringens were investigated. In general, the short 

contact time and the low chlorine dioxide doses applied were not sufficient to inactivate C. perfringens. E. 

coli and coliform numbers were reduced by 1-3 log10 units and intestinal enterococci by 0.8-1.5 log10 units, 

depending on the applied dose, contact time, temperature and the concentration of organic matter in the 

test water. The chlorine dioxide consumption was low in tap water (< 0.1 mg/l after 5 minutes), but 

increased with increasing amount of sewage added to the tap water. A contamination episode will not only 

introduce microorganisms, but also organic and inorganic matter that may cause a chlorine dioxide 

demand. The barrier efficiency of chlorine dioxide against bacterial pathogens introduced to the internal 

distribution system after a contamination episode depends on the applied dose, which has to be higher 

than the chlorine dioxide demand of the actual water. 

Introduction 

Many Norwegian drinking water treatment plants have been upgraded during the last decades. The 

drinking water is therefore generally considered safe when it leaves the drinking water treatment plants, 

and the potential deterioration of the water quality during distribution has come more in focus. Low or 

negative pressure events in drinking water distribution systems have the potential to result in intrusion of 

pathogenic microorganisms if an external source of contamination is present (e.g., nearby leaking sewer 

main) and there is a pathway for contaminant entry (e.g., leaks in drinking water main). In Norway, sewer 

lines are often located in the same ditch as drinking water pipelines. After heavy rain drinking water 

pipelines may potentially be surrounded by sewage-contaminated water. Nygard et al. (2007) showed that 

breaks and maintenance work in the water distribution systems caused an increased risk of 

gastrointestinal illness among water recipients. 

Low or negative pressure events in the drinking water distribution system are often brief and thus are 

rarely monitored or alarmed (Yang et al., 2011). The duration of increased risk of microbial pathogens in 

the drinking water, associated with such episodes, may be short, but may potentially have negative 

consequences for the affected recipients, in particular the vulnerable ones (hospitals, health care institutes, 

food producers etc.). The chlorine residual in water from Norwegian drinking water treatment plant is 

generally too low to act as a barrier against pathogens potentially introduced on the distribution system. 

Recently, there has been an increasing interest of treating the water at the main intake of buildings like 

hospitals-, nursing homes- or hotels for controlling Legionella growth in the internal water distribution 

systems. Chlorine dioxide is considered as a useful method, since it leaves a disinfectant residual which 

has an effect in the whole internal water system, not only at the incoming water like UV-treatment. It is 

also reported to remove old biofilm and reduce the development of new biofilm better than chlorine (at 


least at pH 8), as well as it does not react with natural organic matter to form trihalomethanes or 

haloacetic acids to the same degree as chlorine (Black & Veatch 2010). Chlorine dioxide is widely used 

for treating drinking water worldwide, but is not used at Norwegian drinking water treatment plants. It is 

allowed for use in Norwegian internal distribution systems at levels ≤ 5 mg/l ClO2, and chlorite (ClO2 - ) 

formation should be limited to less than 0.7 mg/l during use (Mattilsynet, 2012). A maximum level of 

chlorite of 0.7 mg/l may limit the maximum applied dose of ClO2 to about 1 mg/l since in worst case 1 

mg/l of ClO2 may be converted to 0.7 mg/l ClO2 - in a one electron shift during oxidation of organic 

matter. High levels of ClO2 may also cause unpleasant smell and corrosion which may be significant in 

cross-linked polyethylene pipes (Tanner, 2011). In practice, only low levels of ClO2 (0.1-0.4 mg/l) is 

therefore used, since these low levels are shown to be effective to prevent the growth of Legionella. For 

treatment of the internal distribution system, the ClO2 generator is placed at the main drinking water 

intake to the building, and ClO2 is dosed according to the water consumption. Such systems are optimized 

for preventing the growth of Legionella, but may also to some extent act as a defense/hygienic barrier 

against faecal contamination, e. g. introduced during negative pressure events in the external distribution 

system. Required Ct values (concentration of ClO2 multiplied with contact time) for inactivation of 

several enteric pathogens are available from the literature (Black & Veatch 2010; Lim et al., 2010), but 

must be supplemented with other information, such as the ClO2 demand of the water and contact times in 

internal distribution systems. The aim of the presented paper was to investigate to what extent ClO2, used 

under laboratory conditions simulating internal distribution systems, was able to inactivate faecal 

indicator bacteria in drinking water contaminated with sewage. 

Materials and methods 

Inlet municipal wastewater was collected at Bekkelaget wastewater treatment plant (Oslo) and filtered 

through 60 µm nylon filter to remove large particles. Tap water was collected at the NIVA laboratory, 

which receive water from Oset water treatment plant (Oslo) with coagulation, filtration, UV-treatment, 

chlorination (low doses) and pH adjustment. The tap water was stored overnight at 4 °C before use to 

reduce potential low levels of free chlorine (< 0.05 mg/l) to avoid interference with the ClO2 disinfection 

and measurements of residual concentrations. The tap water was then added sewage (in general 1:500, but 

in one experiment up to 1:10) for simulating contamination of drinking water during distribution. 

A ClO2 stock solution (2 g/l) was produced by a commercial ClO2 generator (Legio Zon type CDLa) 

which mixes sodium chlorite and hydrochloric acid. 

The sewage-contaminated drinking water was placed in 0.5 l bottles shielded from light (3 bottles for 

each experimental variable). ClO2 was added at levels 0.1-0.5 mg/l. The disinfection experiments were 

performed under gentle mixing at 5±1 °C or 20±1 °C. The effect of contact times of 2.5 min, 5 min and 

7.5 min were investigated. The disinfection process was terminated by addition of sodium thiosulfate to a 

concentration of 10 mg/l after the defined contact times. The experimental set-ups aimed to mimic actual 

ranges of ClO2 dosages, contact times and temperatures during continuous disinfection of internal cold 

water distribution systems. 

The numbers of faecal indicator bacteria were determined in the untreated and ClO2-treated water 

samples and LOG10-reductions were calculated. E. coli and total coliforms were enumerated using the 

commercially available kit Colilert 18® QuantiTray (IDEXX Laboratories). For intestinal enterococci the 

Norwegian Standard method NS-EN ISO 7899-1 was used. C. perfringens were quantified after 

membrane filtration, using mCP agar, anaerobic incubation at 44 C for 24 h, followed by exposure to 

vapours of ammonium hydroxide. 

The ClO2 concentration in the stock solution and the decay of ClO2 during the experiments were 

measured using the Hach 10101-DPD method for ClO2 (0-5 mg/l) utilizing a glycine reagent and DPD 

free chlorine reagent and a spectrophotometer for colorimetric measurements (Hach Company). 

The chemical oxygen demand (COD), total organic carbon (TOC) and pH was measured by standard 

methods. 

Results and discussion 

The sewage-contaminated tap water (1 part sewage and 500 parts tap water) had a pH of 7.8±0.2 and a 

COD of 8.3±0.2 mg O2/l (depending on the variations in the COD in the applied sewage). 


Addition of 0.5 mg/l ClO2 and a contact time of 5 minutes were not sufficient to inactivate C. 

perfringens, but some inactivation of E. coli, total coliforms and intestinal enterococci was observed even 

at the 0.1 mg/l dosage (Figure 1). At dosages typically used in Norwegian internal distribution systems 

(0.2-0.3 mg/l ClO2, 5 min contact time, 5 °C), E. coli was reduced by approximately 2 log10 units and 

intestinal enterococci by approximately 1 log10 units. The test water (Figure 1) had a COD of 8.1 mg O2/l 

and a low chlorine dioxide demand of about 0.1 mg/l after 5 minutes. The low ClO2 demand resulted in 

significant ClO2 residuals measured after the 5 min contact time at all dosages, except at the 0.1 mg/l 

dosage. When ClO2-disinfection is installed at the main intake to real internal distribution systems with a 

dosage 0.3 mg/l, residual doses are seldom measured in the buildings taps during the first months, due to 

biofilm and other ClO2-consuming components in the internal distribution system (Bekkelund, 2012). 

Residual levels are observed in the tap after some months operation, depending on local conditions, after 

the old ClO2-consuming biofilm has been reduced or removed. The effect shown in figure 1 does not take 

into account the ClO2-demand of biofilm in the piping system. The results may therefore only be 

transferred to “real conditions” of internal distribution system if the biofilm has been eliminated by 

previous ClO2-disinfection of the piping system. In addition to biofilm, components in the incoming 

water and pipe corrosion scales may affect the ClO2 consumption in drinking water distribution systems 

(Zhang et al., 2008). 

LOG reducton 

0 

1 

2 

3 

ClO2 dosage (mg/l) 

0 0,1 0,2 0,3 0,4 0,5 

Figure 1 Inactivation (LOG10 reduction) of faecal indicator bacteria in sewage-contaminated tap water 

(COD: 8.1 mg/l) by adding different amounts of ClO2, 5 minutes contact time at 5±1 °C. 

The ClO2 demand was generally low in tap water (< 0.1 mg/l after 5 minutes), but increased when higher 

fractions of sewage was added to the tap water (Table 1). A contamination episode will not only introduce 

microorganisms, but also other organic and inorganic matter that may cause a chlorine dioxide demand. 

When 0.3 mg/l ClO2 was added to sewage diluted 1:10 in tap water, no reduction of E. coli and coliforms 

were observed due to the high ClO2 demand (Table 1). It is probably unrealistic that such high amount of 

sewage will be introduced to drinking water in a negative pressure event, but Table 1 visualize the effect 

of organic matter on the ClO2 demand and bacterial inactivation. 

Table 1 Organic matter (measured as COD and TOC) in tap water and sewage-contaminated tap water 

and its effect on ClO2 demand and bacterial inactivation after addition of 0.3 mg/l ClO2. 

Addition of 0.3 mg/l ClO2 for 5 min, 5°C 

COD TOC ClO2 demand Log reduction Log reduction Ct- 

(mg/l) (mg/l) 5 min (mg/l) E. coli coliforms value 

Tap water (no sewage) 7.9 1.7 0.08 

Sewage-diluted 1:500 8.2 1.8 0.09 1.8 ±0.1 1.7 ±0.2 1.3 

Sewage-diluted 1:100 9.4 2.1 0.14 1.4 ±0.1 1.3 ±0.1 1.2 

Sewage-diluted 1:50 11 2.7 0.19 0.9 ±0.1 0.9 ±0.1 1.0 

Sewage-diluted 1:10 23 6.0 0.64* 0.1 0

The retention time of water in an internal distribution system will vary widely, e. g. depending of the size 

of the building, length of the plumping system, placement of the actual tap and the water consumption. In 

a typical nursing home the average retention time is calculated to 5-6 minutes, but may be both higher and 

lower (Bekkelund, 2012). As shown in figure 2, the inactivation of E. coli and intestinal enterococci after 

addition of 0.3 mg/l was lower when the contact time was reduced. 

LOG reduction 


(COD: 8,5 mg/l, pH 8.0) at different contact times after addition of 0.3 mg/l ClO2 at 5±1 °C. 

The temperature in the internal cold water distribution system will also vary, and this may affect the 

bacterial inactivation. The inactivation of E. coli and coliforms increased by about 1 log10 units when the 

temperature increased from 5°C to 20 °C (Figure 3). 

LOG reduction 

2,5 

Contact time (min) 

5 7,5 

0,5 

0 

1 

2 

3 

4 

1 

1,5 

2 

2,5 

E. coli Coliforms Int. entero 


(COD: 8,5 mg/l, pH 8.0) after addition of 0.3 mg/l ClO2 and 5 minutes contact time at 5 °C and 20 °C. 

In general, continuous disinfection of internal distribution systems with ClO2 may partially act as a 

hygienic barrier (1-2 log10 units reduction) against incoming bacterial pathogens with similar properties as 

E. coli (like Campylobacter and E. coli EHEC), assuming that the ClO2 demand imposed by organic and 

inorganic matter in the incoming water, and internal biofilm, is not too high. The ClO2 doses used for 

internal distribution systems are too low to inactivate incoming bacterial spores, as well as 

Cryptosporidium oocysts and most probably Giardia cysts (Black & Veatch 2010). Some viruses may 

however be inactivated to approximately the same extent as E. coli or intestinal enterococci (Black & 

Veatch 2010; Lim et al., 2010). UV (and a pre-filter) may be a better choice if the only purpose is to 

Session 2: Säker dricksvattenförsörjning 65 

E. coli 

Int. entero 

5 oC 

20 oC

inactivate enteric pathogens in the incoming water, but UV will not have a residual effect and inhibit the 

biofilm and potential Legionella growth in the internal distribution system. 

References 

Bekkelund, A. (2012). Norkjemi. Personal communication. 

Black & Veatch Corporation (2010). White’s handbook of chlorination and alternative disinfectants, 5 th edition. 

Chapter 14: Chlorine dioxide. John Wiley & Sons, Inc. 

Lim, M.Y., Kim, J-M. and Ko, G. (2010). Disinfection kinetics of murine norovirus using chlorine and chlorine 

dioxide. Water Research 44, 3243-3251. 

Mattilsynet (2012). Godkjente kjemiske produkter til behandling av drikkevann. 

http://www.mattilsynet.no/mattilsynet/multimedia/archive/00078/Vannbehandlingsprodu_78681a.pdf 

Nygard, K., Wahl, E., Krogh, T., Tveit, O.A., Bohleng, E., Tverdal, A. and Aavitsland, P. (2007). Breaks and 

maintenance work in the water distribution systems and gastrointestinal illness: a cohort study. International 

Journal of Epidemiology 36(4), 873-880. 

Tanner, B. (2011). Chlorine dioxide for Legionella spp. disinfection: a danger for cross-linked polyethylene pipes? 

Journal of Hospital Infection 78, 242-243. 

Yang, J., LeChevallier, M.W., Teunis, P.F.M. and Xu, M.H. (2011). Managing risks from virus intrusion into water 

distribution systems due to pressure transients. Journal of Water and Health 9(2), 291-305. 

Zang, Z., Stout, J.E., Yu, V.L. and Vidic, R. (2008). Effect of pipe corrosion scales on chlorine dioxide consumption 

in drinking water distribution systems. Water Research 42, 129-136. 


Samband mellan nederbörd uppströms ett dricksvattenverk och 

samtal till sjukvårdsupplysningen gällande mag-tarmsymtom. 

Tornevi Andreas*, Forsberg Bertil ** 

* Miljömedicin, Umeå Universitet, 901 87, Umeå, andreas.tornevi@envmed.umu.se 

** Miljömedicin, Umeå Universitet, 901 87, Umeå, bertil.forsberg@envmed.umu.se 

Abstract. 

Background: Climate change scenarios show that Sweden will be affected by more extreme precipitation. This 

indicates that water treatment plants will face greater challenges since more pathogens are expected to enter 

surface water supplies. Example of pathogen transmission to raw water due to precipitation is by run-offs and 

combined sewer system overflows. 

Göta River is one of two freshwater supplies in Gothenburg and is exposed to upstream combined sewer system 

overflows and farm runoffs. We have earlier analyzed the relations between upstream precipitation and indicator 

bacteria in river raw water, and found the most positive relation 2 days later. The aim of this study is to asses if 

variations in acute gastrointestinal illness (AGI) are explained by precipitation in the area, which may indicate that 

drinking water quality is not always ensured. 

Method: We accessed the daily number of telephone calls (1494 days) to Health Information Service (1177) from 

citizens living in Gothenburg area. It was specified if call considered AGI symptoms, or other symptoms (OS). We 

selected calls from individuals living in real-estates that use Göta River as fresh water supply. To investigate if 

variations in AGI symptoms can be explained by precipitation we fit a model by non-linear distributed lag Poisson 

regression, and control for temperature, day of week and holidays, trends and seasonal patterns. We study a 0-18 

lag day period after precipitation events. We also fit a similar model with OS as response, to study if contacts to 

1177 with AGI symptoms are uniquely related with precipitation. We let Akaike Information Criterion decide final 

structures of the models. 

Results: There is a significant increase of telephone calls regarding AGI symptoms during days with rain (lag 0) 

which relate linearly with amount of rain. Also, there is a significant increase at of calls regarding AGI symptoms 

at lags 4-6 that only occur after heavy rain. No significant relations with precipitation and daily number of phone 

calls regarding OS where found. 

Conclusion: The increase of AGI symptoms 4-6 days after heavy rain may indicate that drinking water quality is 

not always ensured and enhanced technical drinking water treatment could be motivated. 

1. Introduktion 

Klimatförändringsscenarier visar att Sverige kommer att utsättas av mer extrema temperaturer och mer extrem 

nederbörd tillsammans med ett varmare och blötare klimat i allmänhet. Enligt den svenska Klimat- och 

sårbarhetsutredningens rapport kommer ökad nederbörd, som en följd av klimatförändringen, att ha en direkt 

påverkan på dricksvattenkvalitet (SOU 2007:60). Med kraftigare regn kan fler patogener förväntas förekomma i 

råvattentäkter till följd av avrinning och avloppsbräddningar. Den pågående klimatförändringen kommer främst 

att påverka ytvattenkällor, eftersom ytvatten innehåller fler mikroorganismer och uppvisar större och snabbare 

variationer i kvalitet jämfört med grundvatten. 

Världshälsoorganisationen (WHO) har identifierat vattenburen smitta som den allvarligaste hälsorisken 

förknippad med vattenförsörjning. För de utvecklade länderna anser WHO att risken är störst när det gäller 

parasitära protozoer och belyser cryptosporidium som det främsta exemplet på nya hot mot folkhälsan. Sverige 

har nyligen haft två stora utbrott av kryptosporidios där över 20 000 personer både i Östersund (2010) och i 

Skellefteå (2011) uppskattas blivit smittade, och den huvudsakliga källan till smitta berodde på förorenat 

dricksvatten. Förutom studier på utbrottssituationer, har studier också visat dagliga samband mellan ökad 

förekomst av mag-tarmsjukdom vid ökad turbiditet i råvatten eller dricksvatten (Morris, Naumova et al. 1996; 

Schwartz, Levin et al. 1997; Schwartz, Levin et al. 2000; Egorov, Naumova et al. 2003). Även samband med 

nederbörd och besök på akutmottagningar för magsjukdom har rapporterats (Drayna, McLellan et al. 2010). 

Jämförelsevis finns det få studier som syftar till att upptäcka samband med dricksvattenkvalitet och akut 

magsjukdom när inga kända utbrott har inträffat. Det är troligt att utbrottssituationer endast utgör en bråkdel av 

verkliga fall (Reynolds, Mena et al. 2008). 

Göta Älv är en av två kommunala ytvattentäkter till Göteborg, och som utsätts för avrinningar från 

jordbruksmark och emellanåt avloppsbräddningar (Astrom, Petterson et al. 2007). Vi har tidigare analyserat 

relationerna mellan nederbörd uppströms och indikatorbakterier i älven och funnit positiva samband, tydligast 2 

dagar efter nederbörd. 

Syftet med denna studie är att analysera om variationer i mag-tarmsymtom hos befolkningen i Göteborg kan till 

viss del förklaras av mängden nederbörd uppströms Göta älv. Detta kan ge indikationer om 


dricksvattenkvaliteten inte alltid är säkerställd och mer avancerade barriärer i dricksvattenproduktionen kan 

motiveras, särskilt med hänsyn till klimatförändringarna. 

2. Material och metod 

2.1 Dricksvattenproduktion i Göteborg 

Göteborg använder två ytvattentäkter för kommunal dricksvattenproduktion: Göta Älv och Delsjöarna. Göteborg 

har också två kommunala vattenreningsverk, Alelyckan och Lackarebäck. Alelyckan ligger i den norra delen av 

staden och tar i huvudsak sitt råvatten från Göta älv, och distribuerar främst till norra delen av Göteborg. 

Lackarebäck förser dricksvatten främst till södra delen av Göteborg och använder sitt råvatten från Delsjöarna. 

Distributionsnätet är dock sammankopplat genom hela staden och cirka en tredjedel av distributionsnätet kan 

betraktas som en blandzon. 

För att behålla hög vattennivå i Delsjöarna pumpas det ständigt vatten från Göta älv genom en tunnel upp till 

Delsjöarna. Dessutom tillämpas stängningar av råvattenintaget på Alelyckan när råvattenkvaliteten i älven inte 

anses tillräcklig. Då låter man istället råvatten rinna tillbaka från Delsjöarna till Alelyckan, vilket gör att 

Delsjöarna får stå för dricksvattenproduktionen för båda vattenreningsverken. Även om distributionsnäten från 

de två vattenverken är sammankopplade kan geografiska beräkningarna skilja de hushåll som får dricksvatten 

från antingen Alelyckan och Lackarebäck. Vi har definierat Alelyckans leveransområde med de hushåll som 

använder dricksvatten från Alelyckan med sannolikhet 0,95. 

2.2 Miljödata 

Svenska meteorologiska och hydrologiska institutet (SMHI) har försett oss med dygnsnederbörd ca 30 km 

uppströms (Alvhem) från råvattenintaget till Alelyckan, samt dygnstemperatur från Göteborg. Valet av denna 

nederbördsstation grundar sig på att denna plats har i vår tidigare forskning visat på tydligast samband med 

råvattenkvalitet (turbiditet och indikatorbakterier) utanför intaget vid Alelyckan några dagar senare. 

Figur 1. Uppmätta nederbördsmängder under perioden 2007-11-29µ2011-12-31 i Alvhem, ca 3mil uppströms 

råvattenintaget på Alelyckans dricksvattenverk. Horisontella linjer representerar urval av nederbörds percentiler 

under perioden. Nederbörd förekommer 46 % av dygnen. 

2.3 Hälsodata 

Vi har inhämtat alla telefonsamtal till Sjukvårdsupplysningen (1177) från personer med hemadress i Göteborg. 

Data fanns tillgängligt under perioden 2007-11-29 ••2011-12-31. Data innehöll information om tidpunkt och om 

symptom var relaterat till akut mag-tarmsjukdom (AGI). Övriga symptom var ospecificerade. Samtal från 

individer boende i Alelyckans leveransområde separerades från övriga samt om kontaktorsak gällde AGIsymtom 

eller övriga symtom. Data aggregerades sedan till antal telefonsamtal per dygn. 


Figur 2. Antal samtal per dygn till 1177 gällande mag-tarmsymtom från personer med hemadress kopplat till 

Alelyckans vattenverk under perioden 2007-11-29µ2011-12-31. Totalt 25 659 samtal. En splinefunktion med 5 

frihetsgrader/år beskriver trend och säsongsvariationer. 

2.4 Statistisk analys 

Vi har studerat sambandet mellan dagligt antal telefonsamtal med AGI symtom, från Alelyckans leveransområde 

(PCAGI) till 1177, och dygnsnederbörd genom tidserieregression. Vi antar att PCAGI följer en 

Poissonfördelning, och för att undersöka om variationer beror på nederbörd anpassade vi en generaliserande 

additiv regressionsmodell (GAM). Vi justerade för säsongsvariationer, tidstrend, röda dagar och dagar i 

anslutning till röda dagar, veckodag och dygnstemperatur. Tidstrend och säsongsvariationer justerades med hjälp 

av en mjuk splinefunktion. För att modelera effekter på PCAGI som eventuell endast inträffar efter kraftigt regn, 

tillåter vi ickelinjära samband med mängden nederbörd. För att beakta inkubationstider av eventuell vattenburen 

smitta samt distribueringstiden från råvatten till tappkran, analyserade vi en 18 dagars lag-period efter 

dygnsnederbörd. För att ta hänsyn till den seriella korrelationen i väderförhållanden anpassade vi en icke-linjär 

lag-fördelnings modell (Gasparrini, Armstrong et al. 2010). Vi anpassade också en liknande modell för samtal 

gällande övriga symptom (PCOS) . Detta för att undersöka om samband mellan nederbörd och telefonkontakter 

gällande AGI-symtom skiljer sig från övriga kontaktorsaker. Vi lät Akikes Informations Kriterium välja 

lämpligast sambandsmodell för PCAGI och PCOS. Analyser har genomförts i R (version 11.1). 

3. Resultat 

Samband mellan nederbörd och antal samtal till 1177 gällande mag-tarmsymptom under perioden 2007-11-29 - 

2011-12-31 konstaterades signifikant under första veckan efter regn. De tydligaste sambanden påvisades samma 

dag som nederbörd (lag 0) samt omkring 5 dagar efter nederbörd. Sambandet vid lag 0 anpassas till ett i det 

närmaste linjärt positivt samband, medan effekten vid lag 4 - 6 förklaras som en icke-linjär relation, med positiva 

effekter vid kraftigt regn (> 20 mm/dygn). Figur 2 visar relationen mellan mängden nederbörd, 0-18 dagar 

tidigare och relativ effekt på antalet samtal med AGI symtom, samt vid 30 mm regn för att illustrera 

konfidensintervall. För samtal till 1177 gällande övriga symtom tillförde inte nederbörd till att 

modellanpassningen förbättrades, och inga signifikanta samband kunde fastställas. 


Figur 3. Relativa effekter av dygnsnederbörd, 0-18 dagar tidigare, på dagligt antal samtal till 1177 gälland magtarmsymtom. 

Vänster bild visar nederbörds mängder 0-45 mm. Höger visar relativ effekt vid 30 mm regn där 

skuggat område är konfidensintervall av modellerat samband. 

4. Diskussion 

Varför antal samtal gällande mag-tarmsymtom till 1177 påverkas av nederbörden samma dag finns i nuläget 

ingen hypotes för att det skulle vara dricksvattenrelaterat, men att människors välbefinnande påverkas av vädret 

har ofta diskuterats. Dock ser vi ingen signifikant ökning av samtal gällande övriga symtom vid dagar med 

nederbörd. Att vi påvisar en ökning 4-6 dagar efter kraftigt regn kan indikera dricksvattensmitta. Vi har tidigare 

sett att råvattnet är tydligast påverkat av nederbörd 2 dagar senare, samt kan man generalisera produktionstiden 

till 1 dygn. Om då ökningen PCAGI 4-6 dagar efter kraftigt regn beror på dricksvattnet har vi en inkubationstid 

på 1-3 dagar, förutsatt en kort tid till agerande för sjukvårdsrådgivning. Bakterier och virus beskrivs vanligtvis 

med denna inkubationstid. 

Analyser med data från sjukvårdsupplysningen (1177) har sina fördelar med att en relativt hög andel av 

befolkningen använder denna tjänst vilket gör att relationssamband blir lättare att identifiera. Dock så har denna 

typ av sjukvårdskontakt inga fastställda diagnoser vilket gör att slutsatser är svårare att fastslå. Denna studie 

motiverar till fortsatt forskning med hälsodata där diagnoser fastställts, men rapporterar att samband mellan 

nederbörd och mag-tarmsymptom förekommer. 

Referenser 

Regeringen (2007). SOU 2007:60 ••Sverige inför klimatförändringarna hot och möjligheter••. 

Bilaga B13 Dricksvattenförsörjning. 

Astrom, J., S. Petterson, et al. (2007). "Evaluation of the microbial risk reduction due to selective closure of the raw water 

intake before drinking water treatment." J Water Health 5 Suppl 1: 81-97. 

Drayna, P., S. L. McLellan, et al. (2010). "Association between rainfall and pediatric emergency department visits for acute 

gastrointestinal illness." Environ Health Perspect 118(10): 1439-1443. 

Egorov, A. I., E. N. Naumova, et al. (2003). "Daily variations in effluent water turbidity and diarrhoeal illness in a Russian 

city." Int J Environ Health Res 13(1): 81-94. 

Gasparrini, A., B. Armstrong, et al. (2010). "Distributed lag non-linear models." Statistics in Medicine 29(21): 2224-2234. 

Morris, R. D., E. N. Naumova, et al. (1996). "Temporal variation in drinking water turbidity and diagnosed gastroenteritis in 

Milwaukee." Am J Public Health 86(2): 237-239. 

Reynolds, K. A., K. D. Mena, et al. (2008). Risk of waterborne illness via drinking water in the United States. Reviews of 

Environmental Contamination and Toxicology, Vol 192. D. M. Whitacre. 192: 117-158. 

Schwartz, J., R. Levin, et al. (2000). "Drinking water turbidity and gastrointestinal illness in the elderly of Philadelphia." J 

Epidemiol Community Health 54(1): 45-51. 

Schwartz, J., R. Levin, et al. (1997). "Drinking water turbidity and pediatric hospital use for gastrointestinal illness in 

Philadelphia." Epidemiology 8(6): 615-620. 


Reduced risk for waterborne virus infections for society despite 

climate change - VISK 

1* Lena B Blom, 1 Joanna Friberg, 2 Kjetil Furuberg, 3 Per-Eric Lindgren, 4 Gregory M 

Morrison, 5 Mette Myrmel, 6 Jakob Ottoson, 7 Anna Charlotte Schultz, 8 Lena Solli Sal, 

9 Magnus Simonsson 

1* 

City of Göteborg, Department of sustainable Water and Waste Management, Box 11192 Göteborg 

2 

Sweden, lena.blom@kretslopp.goteborg.se, joanna.friberg@kretslopp.goteborg.se, Norsk Vann, 

kjetil.furuberg@norskvann.no, 3 Länssjukhuset Ryhov, Miljöbiologiska laboratoriet, Laboratoriemedicin, pereric.lindgren@liu.se 

4 Water Environment Technology, Department of Civil and Environmental Engineering, 

5 

Chalmers University of Technology, (greg.morrison@chalmers.se), Norges Vetrinärhöjskole, 

mette.myrmel@veths.no, 6 Statens Vetrinärmedicinska Anstalt, jakob.ottoson@slu.se, 7 Danmarks Tekniske 

Universitet, Födevareinstituttet, Afdeling for Mikrobiologi og Risikovurdering, acsc@food.dtu.dk, 8 Nedre 

Rommerike Vannverk, lena.sal@nrva.no, 9 Livsmedelsverket, SLV, magnus.simonsson@slv.se 

Abstract. There is some concern within the Nordic region concerning the presence and dispersion of 

waterborne pathogenic viruses in drinking source waters and with the added prospect of climate change. 

This concern is addressed in the EU-VISK project with the coordination of a number of ongoing studies 

and research projects. Further, VISK promotes knowledge and competence for societal action, which is 

relevant for human well-being and the quality of life. VISK will provide a basis for both preventive 

(decreased likelihood) and reactive (reduced consequence) actions based on the latest risk assessment 

research. The aim is to provide decisions and measures based upon performed risk assessment within the 

water cycle, from source to tap. 

VISK includes 18 partners, with stakeholders from municipalities, industrial organizations, academia and 

authorities, to provide a complete and holistic approach. This is the first inter-regional approach for 

pathogens in Scandinavia, which provides another link for the area. The project activities match 

competence, interests and geographical spread. The VISK work packages include; project leadership, 

epidemiology, mapping, virus reduction, risk communication, communication strategies, as well as 

dissemination and communication of results. 

VISK has formed a network of competence for sustainable and safe drinking water systems, where 

municipalities within the region and beyond can seek advice for contingency and water safety plans. VISK 

results will be collated in a communication and action plan, which will be disseminated to politicians, water 

industry stakeholders and society. The aim is to enable correct decision-making. An open home page 

already exists (www.VISK.nu) to promote the communication of VISK results through handbooks, 

newsletters and reports. One example of the results from VISK is an early warning system which has been 

identified as important. Further, a survey has proven that trust and confidence in the drinking water and its 

providers before a potential incident occurs is important. The modelling of the spread of viruses in a raw 

water source will provide support for risk assessment analyses. An indication of whether a pathogenic 

virus is viable, or not, has proven a significant challenge for analysis. Another challenge is to achieve 

concentration of the samples before analysis. 

Introduction 

A safe and healthy drinking water is essential for all humans. In structured analyses carried out within the 

municipality of Gothenburg, microbiological risk was identified as one of the most important aspects to 

achieve the goal of good and healthy drinking water. Predicted climate change will lead to more intense, 

and more frequent, rainfall events e.g. in the region of Kattegatt-Skagerack-Öresund and thereby increase 

the risk of microbiological influence on raw water sources (Thysell et.al. 2007). With heavier rain the risk 

of overflowing sewers increases. The VISK project handles increasing risk with predicted higher 

concentrations of pathogens in the raw water and best practises to produce safe drinking water. The aim is 


the provision of safe drinking water in the future and at the same time handling the risks for water borne 

virus infections and to enable correct decision making 

The use of water safety plans (WSP) can provide information about whether a water supply system is 

capable of producing drinking water that meets the health-based targets (Medema and Smeets 2009, 

Medena et.al. 2006). The use of quantitative microbiological risk assessment (QMRA) provides an 

estimation of the microbiological risk included in the water safety plan (Smeets et.al. 2010, Davison and 

Howard 2005). However, the quantitative assessment is limited due to knowledge gaps relating to the 

virus load in drinking water sources, the specific strains responsible for outbreaks of waterborne virus 

infections as well as the infectivity and virulence of these strains. A better understanding in the removal 

and inactivation of viruses in drinking water treatment processes is further needed. Early warning systems 

(EWS) are organization routines and information systems allowing us to systematize events in time and 

space, and evaluate single events differing from the norm as well as patterns of outbreaks (Guglielmetti et 

al. 2006). Finding ways to detect and characterize outbreak signals can support preventive work and early 

investigations, which in turn can reduce the size of the outbreak. 

Methods 

Water borne viruses are dispersed in the water cycle (Figure 1). The raw water may be influenced by 

untreated waste water especially during periods of heavy rain (Thysell et.al. 2007). Further, wastewater 

treatment plants may receive too much incoming sewage water with lowered treatment efficiency of the 

wastewater and sewage plant overflows. When this occurs citizens in the connected area may be exposed 

to potential sickness through microbiological virus infections, as viruses are released to the receiving 

water for the wastewater treatment plant. This recipient can be raw water for any municipality 

downstream e.g. if surface water from a river is used. The conventional drinking water process used today 

does not effectively remove viruses and parasites, being originally designed for reducing bacteria. Viruses 

and parasites might therefore pass through the drinking water treatment plant and may be distributed to 

the consumer. The consumer might get sick if drinking water contains viruses and parasites. There are 

also problems with detecting viruses as the analysis is time consuming and are impossible today to 

implement on line and to use as steering for the intake of the raw water or the drinking water process. 

Therefore today other parameters for controlling the drinking water plant are applied including e.g. other 

pathogens and upstream information such as EWS. 

Figure 1 The waterborne virus water cycle. 

Within the VISK project different experts are gathered from Nordic countries from different disciplines to 

work together to learn more and to be able to perform a structured work on waterborne viruses. VISK 

includes 18 partners, with stakeholders from municipalities, industrial organizations, academia and 


authorities, to provide a complete and holistic approach. This is the first inter-regional approach for 

pathogens in Scandinavia, which provides another link for the area. Within the VISK project the whole 

virus cycle is of concern and investigated with risk evaluation in focus. The work is divided into different 

work areas including epidemiology, mapping, treatment, risk communication, communication strategy 

and communication and results. 

In the epidemiology part of the work an investigation of an EWS is performed as well as a survey - the 

Ale H2O study of drinking water habits related to stomach sickness. The early warning system includes a 

systematisation of the sickness information data and the potential use in the drinking water industry. 

The mapping part includes a large scale sampling program in water of viruses in raw water, sewer outlets, 

inflow to sewage treatment plants and side flow in 15 sampling sites in the Göta River and a more limited 

number in the river Glomma. There is also mapping of selected human virus types and levels as well as 

faecal indicators in mussels outside the recipients of the rivers to achieve a baseline for a two-year 

monitoring program. Hydrodynamic modelling in the rivers Göta River and Glomma are performed using 

the mapping data for validation to investigate the spread of the viruses in the rivers. It is also possible to 

use potential scenarios in the modelling part of the work. 

In the treatment part of the project the main focus lies on viral removal during ultra filtration and virus 

inactivation in disinfection processes (UV light and chlorination) under Scandinavian conditions. The 

results will enhance the understanding of the mechanisms of viral removal and inactivation providing the 

opportunity for process optimization and reducing risk. 

The risk communication focuses on systemising the results of the epidemiology, mapping and the 

treatment in a risk model to be used by water treatment plants (WTPs) in their water safety planning. 

Relevant figures on the viral load in the source water, taking into account spatial and temporal variability, 

enables WTPs to target their treatment. Improved understanding of viral removal and inactivation 

mechanisms will help in monitoring and surveillance in order to guarantee that these targets are met. 

Tools to better predict when the source water is at its most vulnerable, thereby enabling corrective actions 

to be taken, minimizing the risk of outbreaks to occur, is another important outcome of the risk 

communication work package. Altogether this will enable correct decision making, giving possibilities 

for healthy and safe drinking water. 

Communication strategy is used to evaluate the necessity of trust and confidence in drinking water 

coupled to waterborne virus outbreak and also more importantly how social trust is built between 

outbreaks. This is investigated in an ongoing survey in a municipality in the Ale H2O study. It is known 

that confidence in drinking water is high, but that this is quickly eroded during an outbreak. At this point 

social trust in those who manage and operate the system becomes important. In the Ale H20 study we are 

for the first time investigating social trust between outbreaks and will provide advice to practitioners 

based on the results of the study. 


Investigation and evaluation of warning systems for water borne outbreaks of gastroenteritis have been 

conducted within the VISK project. Comparisons between different data sources and statistical analysis of 

the data showed that calls to the Swedish national medical care hotline, 1177, proved to be a specific and 

relevant source of outbreak signals. 1177 offers the possibility of a national system for early detection and 

profiling of outbreaks, but further development of IT-systems and information services, as well as 

regional and local establishment of common guidelines and routines, and systems for defining and 

handling signals of outbreak are needed. A suggestion is to develop a system with integrated functions for 

detection and profiling, which gives better support to the investigation. 

Preliminary data from the baseline study of levels of norovirus in mussels sampled downstream the 

sewage treatment plants of Göta River, shows a tendency towards a seasonal pattern (figure 2). 


Figure 2 Distribution of norovirus (genogroups, GI and GII) and E. coli in mussels during a 13-months 

sampling period from the south end of Göta River. 

A survey has proven that trust and confidence in the drinking water and its providers before a potential 

incident occurs is important. The modelling of the spread of viruses in a raw water source will provide 

support for risk assessment analyses. Whether a pathogenic virus is viable, or not, has proven a great 

challenge since the analyses does not give this answer. Another challenge is to achieve concentration of 

the samples before analysis. Since the viruses are very rare in raw water and extremely difficult to gather 

and requires large amounts of samples that needs pre-concentration before analysis. 

The main results for the project will be gathered in a network of competence for sustainable and safe 

drinking water systems in the Nordic countries. The results will also be collated in a handbook for the 

water industry, which will include examples of best practice, as well as guidelines for communication and 

action plans. 

References 

Guglielmetti P., Coulombier D., Thinus G., Van Loock F., Schreck S. (2006). The early warning and response system 

for communicable diseases in the EU: an overview from 1999 to 2005. Euro Surveillance. 11(12):215-20. 

Medema, G., Loret, J.-C., Stenström, T. A. and Ashbolt, N. (2006). Quantitative Microbial Risk Assessment in the 

Water Safety Plan. Final Report on the EU MicroRisk Project. Brussels, European Commission. WHO (2011). 

Guidelines for Drinking-water Quality Fourth Edition. World Health Organization, Geneva. 

Medema G., Smeets P., (2009) Quantitative risk assessment in the Water Safety Plan: case studies from drinking 

water practice, Wat. Sci. Tech. Wat. Supp. 9(2) 127-132. 

Smeets P. W. M. H., Rietveld, L. C. van Dijk J. C. and. Medema G. J, (2010) Practical applications of quantitative 

microbial risk assessment (QMRA) for water safety plans, Wat. Sci. Tech. 61(6), 1561-1568. 

Thysell U., Kant H., Moberg S., Bäckman H., Svensson G., Hernebring C., Ljunggren O., (2007) 

Klimatförändringarnas inverkan på allmänna avloppssystem- Underlagsrapport till Klimat- och 

sårbarhetsutredningen, Svenskt Vatten rapport, M134, ISSN nr: 1651-6893. 


Experience from workshops on Good disinfection practice 

(GDP) and microbial risk assessment (MRA) 

Gerald Heinicke 1 , Josefin Abrahamsson 2 , Peder Häggström 3 , Britt-Marie Pott 4 , Helena 

Almqvist 5 , Elisabet Athley 6 , Gullvy Hedenberg 7 

1 DHI, ghe@dhigroup.com, 2 Göteborg Vatten, josefin.lundberg.abrahamsson@vatten.goteborg.se, 

3 Stockholm Vatten, peder.haggstrom@stockholmvatten.se, 4 Sydvatten, britt-marie.pott@sydvatten.se, 

5 Sweco Environment, helena.almqvist@sweco.se, 6 Göteborg Vatten, 

elisabet.athley@vatten.goteborg.se, 7 Svenskt Vatten, gullvy.hedenberg@svensktvatten.se 

Abstract. In the autumn of 2011, workshops were held in four Swedish cities on the application of two 

methods for assessment of the microbial barriers necessary in water works: Good Disinfection Practice 

(GDP) and the Microbial Risk Assessment (MRA) tool. This paper describes recent developments and 

summarizes the experience from the workshops. 

GDP was developed in Norway as a method to identify the need for additional disinfection barriers, 

based on water analysis (indicator organisms and cryptosporidium, if available), and the existing 

treatment. Its application is outlined in a guidance document (Ødegaard et al., 2009). 

The MRA modelling tool was developed for Svenskt Vatten and adepts Quantitative Microbial Risk 

Assessment for application on Swedish surface water works (Abrahamsson et al., 2009). Several 

modules of the MRA were updated during 2011, especially conventional treatment and chlorination. 

Workshops were held in Uddevalla, Gävle, Eskilstuna and Växjö, first on GDP and some weeks later on 

MRA. In total, about 80 participants from about 35 municipalities joined the workshops, which included 

an introduction of the method, followed by hands-on work with participantÑs own water works. 

GDP was the more easily accessible method, as it only requires information that is commonly available 

at water supplies. It is a relatively rigid guidance method with built-in safety margins that relatively easily 

leads to recommendation regarding the disinfection method and dose (inactivation barrier). 

The MRA tool is more suited for specific investigations, and demands more initiative by the user. The 

tool allows for a close adaptation to the water supply modelled, also for filtration processes that remove 

microorganisms rather than inactivate. In addition to the assessment of the treatment barriers under 

normal (baseline) conditions, the method is especially suitable to assess the risk related to incidents, 

such as events with heavy pollution of the raw water, or failure of a process. 

To optimize the benefit of the tools it is recommended to start with a survey of fecal pollution sources in 

the raw water source. The second step is to generate a recommendation on the necessary barrier effect 

by using the GDP tool. Finally, a scenario analysis of normal behavior of the waterworks (baseline 

conditions) and specific risk events may be created with the MRA tool. 

It is our experience from the workshops that GDP and MRA work quite well as complementary methods 

for quantifying the need for microbial barriers in water supplies. Measures have been identified to further 

increase their applicability. These include the preparation of a guidance document to the use of GDP 

specific under Swedish conditions and the inclusion of new functionality in the MRA modelling tool. The 

chlorination modules of the two methods should be made more compatible. 

Introduction 

The most important function of drinking water treatment is to produce safe drinking water that does not 

cause microbial infections of the consumers. Bacteria, virus and protozoan parasites pathogenic to 

humans may be present in surface and ground waters. Protozoan parasites have been identified in many 

Swedish surface waters, and two large outbreaks have occurred recently(SMI, 2011). 

As a guidance whether the microbial barriers at a water works are sufficient, Swedish water supplies 

have three sources of information. 

1. Livsmedelsverket••s regulations (SLV, 2011) state that a water supply needs sufficient 

microbial barriers. The corresponding guideline document (SLV 2006) details that for ground 

waters, generally 1-2 microbial barriers are sufficient while surface waters generally need 2-3 

independent barriers. The guidelines also suggest that if several barriers are applied, they 


should apply different mechanisms. A combination of barriers that physically remove particles 

(i.e. filters) and inactivating barriers (disinfection processes) is preferred. 

The barrier concept in the regulations is necessarily simplified. In reality, the efficacy of barriers is 

known to vary between different types of microorganisms. For example, the protozoan parasites 

Giardia and Cryptosporidium are largely resistant to chlorination, while some viruses are quite 

resistant to UV irradiation. 

Recently developed risk-based guidelines and tools include ••God desinfektionspraxis••(GDP) and 

Microbial Risk Assessment, which regard the microbial barriers at waterworks quantitatively for 

bacteria, virus and protozoa. These methods can be applied to further investigate the height of the 

microbial barrier in the waterworks: 

2. GDP was developed in Norway as a method to identify the need for additional disinfection 

barriers, based on water analysis (indicator organisms and cryptosporidium, if available), and 

the existing treatment. Its application is outlined in a guidance document (Ødegaard et al., 

2009). Method development was co-financed by Svenskt Vatten. 

3. The MRA modelling tool was developed for Svenskt Vatten (Abrahamsson et al., 2009), 

based on research work carried out at Smittskyddsinstitutet and other research institutes. The 

tool adepts the scientific method ••Quantitative Microbial Risk Assessment•• (QMRA) for 

application on Swedish surface water works. Several modules of the MRA modelling tool 

were updated during the autumn of 2011, especially regarding conventional treatment, 

membrane filtration and chlorination. 

Svenskt VattenÑs workshops 2011 

Workshops were held in Uddevalla, Gävle, Eskilstuna and Växjö, first on GDP and some weeks later 

on MRA. In total, about 80 participants from about 35 municipalities joined the workshops, which 

included an introduction of the method, followed by hands-on work with participant••s own water 

works. Furthermore, Smittskyddsinstitutet (SMI) informed about their sampling program for 

pathogens. 

Public information 

A public project site on GDP and MRA was established and offers shared documents, news and the 

possibility to post questions and messages. 

Address: http://mra.team.dk.dhigroup.com 

General user name for visitors (read only): TEAM\besoekare.mra 

Password: odpmra 

A personal user name with the right to contribute is available through contact with the author. 

Experience from workshops 

Although the level of preparation by the participants and the water supplies investigated were widely 

different, it was possible for everybody to do some meaningful work using the methods. 

Application of GDP and MRA on the same water supply 

The GDP method only requires information that is normally available at water works, and this makes it 

easy to start with. For most users, it was not too difficult to end up with a recommendation regarding 

method of disinfection and a suitable dose using GDP. 

The MRA tool needs more input and initiative by the user and is thus more suited for specific 

investigations, for example failure of a process. If good input data is available, the tool may be well 

adapted to the specific water works and may take care of both inactivation and filtration processes. 

After tuning the model to match the water works under normal conditions, it is suitable for risk 

assessment regarding incidents such as polluted raw water or failure of some process component. The 

MRA tool is available for free and open for further extensions, improvements and updates of the 

default data. 


It was found that the GDP approach with assumptions and calculations regarding the Ct-values 1 in 

chemical disinfection work quite well to prepare in-data for the corresponding modules in the MRA 

tool. GDP and MRA however use two separate concepts to describe the hydraulics in the contact tank. 

In GDP, the effective residence time is used, i.e. when 10% of the dosed concentration has passed the 

tank. The MRA modelling tool uses the number of completely stirred tanks (CSTR) concept. While a 

translation is not straightforward, Table 1 states an empirical relationship between the two. Especially 

in the MRA tool, the log-reduction achievable by chlorination result is extremely dependant on the tank 

hydraulics. 

Table 1 Chlorination contact tank hydraulics: estimate of the number of completely stirred tanks (CSTR) 

in the MRA modelling tool compared to the t10/t values applied in GDP (adapted from Ødegaard et al., 

2009). 

Degree of plug 

flow 

None (ideal 

mixing) 

t10/t Description from GDP Approx no. of 

CSTR 

0.1 No screens, completely mixing, high velocity flow at 

inlet and outlet. 

Poor 0.3 No screens, one or several in- or outlets 3 

Intermediate 0.5 Screens at inlets and outlets, some baffles 5 

Quite good 0.7 Screens at inlets and outlets, some baffles, much 

longer than wide 

Very good 0.9 Screens at inlets and outlets, some baffles, extremely 

much longer than wide 

Plug flow 1.0 Flow as in an ideal pipe •• 

The MRA tool in its current form explicitly addresses surface water works. For water supplies based on 

ground water or artificial recharge, it was difficult to state realistic pathogen concentrations in the raw 

water. In case of artificial recharge, it was assumed that the processes achieved log-reductions of model 

pathogens in the higher end of the range reported for slow sand filters. For ground water supplies 

normally not affected by surface waters, it was attempted to define possible contamination events, and 

do a risk assessment of these. 

When the same surface water supply was investigated, both methods normally identified lacks in 

barrier height. Water works with raw water affected by wastewater that apply final disinfection by 

chlorination typically lack barrier height against protozoan parasites, while works with UV-disinfection 

may be close to the limit for viruses. 

In both methods, the description of the raw water is problematic. In GDP, even a single measurement 

of E.Coli above 10/100 ml during the last three years results in a pre-classification as heavily polluted 

(class D). In many cases, a risk-based sampling program of at least 24 samples a year including 

Giardia and Cryptosporidium is unrealistic to implement. Then, the source water is assumed to be in 

the worst category. In this way, a well-protected lake with faecal indicator organisms absent in most 

samples may end up in the same category as a heavily polluted river. In MRA, the user needs to state 

the concentrations of eight model pathogens. As such data currently are not available for source waters, 

default values are commonly applied. As these values are quite high and somewhat arbitrary, also 

MRA can be assumed to generally overestimate the pathogen load in the source water. However, 

results from large sampling programs abroad, reported in the literature, have shown instances with high 

pathogen loads. 

Actions towards improved applicability 

After the workshops, the group of people involved identified issues and actions to improve the 

applicability of the GDP method and the MRA modelling tool. 

1 Concentration integrated over time 

Session 2: Säker dricksvattenförsörjning 77 

1 

18 

>170

GDP: The method was found applicable for Swedish water works, but aspects such as the attribution of 

barrier height (log-credits) to properties of the water were not in line with the current regulations. It 

was decided to prepare a guidelines document for application under Swedish conditions, including 

relevant examples. The main issues to be addressed are: 

Artificial groundwater recharge is a common practice in Sweden, and currently difficult to 

address using the GDP method. 

Currently, the upper limit regarding the log-credit given for water treatment and operational 

monitoring (3-log bacteria, 3-log virus, 3-log protozoa) may result in an underestimation of 

consecutive and independent treatment barriers. As a result, UV-disinfection may be the only 

way to satisfy GDP. The guideline should open for granting higher log-credit for other 

independent filtration barriers. 

Furthermore, it was decided to call the method God desinfektionspraxis (Good disinfection practice, 

GDP) instead of the earlier Optimal desinfektionspraxis (Optimal disinfection practice). 

MRA: A list was created with issues identified during the workshops, to improve the applicability of 

the tool: 

Model bugs and data errors in the existing modules (to be fixed). One important uncertainty is 

the choice regarding the use of data for chlorine susceptibility of microorganisms. Several data 

sets exist in the scientific literature, and the values are quite different. 

Suggestions for improved documentation. One misleading issue is the case of Adenovirus, 

which with current assumptions regarding raw water concentrations and high UV-resistance 

often results in probabilities of infection above acceptable risk thresholds. The microbiologists 

in the group did not regard Adenovirus as a relevant human pathogen under Swedish 

conditions. A detailed statement is necessary. 

Suggestions for new and extended functions (wish list), including chloramination, chlorine 

dioxide, and artificial recharge. 

To ease the application of both methods in parallel, the chlorination module should be made more 

compatible. 

Conclusions 

GDP and MRA work quite well as complementary methods for quantifying the need for microbial 

barriers in water supplies. Experience from parallel GDP and MRA investigations on specific water 

supplies show that the two independent methods normally come to the same conclusions, i.e. 

concordantly identify water works with insufficient microbial barriers. 

GDP is the more easily accessible, as it only requires information that is commonly available at water 

supplies, such as concentrations of indicator organisms. It is a relatively rigid guidance method with 

built-in safety margins that relatively easily leads to recommendation regarding the disinfection method 

and dose (inactivation barrier). 

The MRA tool is more suited for specific investigations, and demands more initiative by the user. In 

addition to the assessment of the treatment barriers under normal (baseline) conditions, the method is 

especially suitable to assess the risk related to incidents, such as events with heavy pollution of the raw 

water, or failure of a process. 

A suitable work flow would be the following: 

1. Survey of fecal pollution sources in the raw water source 

2. GDP - general recommendation on necessary barrier effect 

3. MRA - Scenario analysis (baseline and specific risks events) 

Measures have been identified to further increase their applicability. These include the preparation of a 

guidance document to the use of GDP specific under Swedish conditions and the inclusion of new 

functionality in the MRA modelling tool. 


Acknowledgements: 

In addition to the authors of this conference paper, the following people have contributed to the 

progress in improving the GDP and MRA tools and applying them in Sweden: Kjetil Furuberg (Norsk 

Vann), Susan Petterson (Water & Health Pty Ltd / Norwegian University of Life Sciences), Nick 

Ashbolt (USEPA), Olof Bergstedt (Göteborg Vatten), Thorbjörn Lindberg (Livsmedelsverket), Anette 

Hansen, Caroline Schönning and Thor Axel Stenström (Smittskyddsinstitutet). 

Abrahamsson, J.L., Ansker, J. and Heinicke, G. (2009) MRA ••Ett modellverktyg för svenska vattenverk, SVUrapport 

2009-05. Svenskt Vatten. www.svensktvatten.se. 

Häggström, P., Pott, B.M. Athley, E., Almqvist, H. (2012) Svenskt Vattens workshops hösten 2011, PM version 

2012.01.11. Available from public project site, using visitor login as described in the text. 

SLV (2006) Vägledning Dricksvatten. Version 2006.03.01, Livsmedelsverket. www.slv.se. 

SLV (2011) Livsmedelsverkets föreskrifter om dricksvatten. SLVFS 2001:30 inkl. ändringar 2011:3, 

Livsmedelsverket. www.slv.se. 

SMI (2011) Cryptosporidium i Östersund. Artikelnr. 2011-15-4 

Ødegaard, H., Østerhus, S. and Melin, E. (2009) Veiledning til bestemmelse av god desinfeksjonspraksis. Rapport 

170, Norsk Vann. www.norskvann.no. 


NORVID projektet – analys av norovirus i 

dricksvattenberedningen 

Fredrik Nyström*, Elisabet Athley**, Per Ericsson***, Peder Häggström****, Britt-Marie 

Pott*****, Johanna Ansker******, Per-Eric Lindgren******* 

* Medicinsk Mikrobiologi, Linköping Universitet, 581 85 Linköping, fredrik.nystrom@lj.se 

** Göteborg Vatten, 424 23 Angered, elisabet.athley@vatten.goteborg.se 

*** Norrvatten, 169 02 Solna, per-ericsson@norrvatten.se 

**** Stockholm Vatten VA AB, 106 36 Stockholm, peder.haggstrom@stockholmvatten.se 

***** Sydvatten AB, 211 19 Malmö, britt-marie.pott@sydvatten.se 

****** Stockholm Vatten VA AB, 106 36 Stockholm, johanna.ansker@stockholmvatten.se 

******* Medicinsk Mikrobiologi, Linköping Universitet, 581 85 Linköping, per-eric.lindgren@liu.se 

Abstract. Norovirus is a viral pathogen that cause acute gastrointestinal disease. Common sources of 

infection include person-to-person, ingestion of contaminated food or contaminated water. Norovirus is 

today believed to be behind several water-borne disease outbreaks for which the etiology could not be 

determined. Swedish drinking water treatment plants have been traditionally modeled to remove 

contamination of fecal bacteria but recently a greater awareness regarding both viral and protozoal 

contamination has increased the demand for additional treatment steps such as UV or ultrafiltration. In 

this study we sampled and analysed source water from four large drinking water treatment plants in 

Sweden together serving over 2 500 000 consumers with clean drinking water. Samples were taken 

every second week and subjected to a three-step adsorption-elution filtration method in order to 

concentrate the virus particles in the water sample. The samples were then analysed for norovirus of 

genogroup I and genogroup II using a molecular detection method called real-time PCR. If present 

norovirus load was quantified using a standard curve of known dilutions. Norovirus of both genogroups 

were detected mainly in the winter season. Quantifiable levels of norovirus genogroup II was 

significantly greater than those of genogroup I (p

Sjukdomsbilden karaktäriseras av relativt snabbt förlopp som inleds med plötsliga kräkningar och 

diarréer. Den har skämtsamt benämnts som ”two-bucket disease” och sprids främst via person-tillperson, 

livsmedel eller via förorenat vatten. Viruset är oerhört smittsamt och det har beskrivits att så 

lite som 10-100 viruspartiklar skulle vara tillräckligt för att orsaka sjukdom (Atmar et al., 2008; Patel et 

al, 2009). Därtill utsöndrar en infekterad individ i storleksordningen 10 12 viruspartiklar per gram 

avföring (Atmar et al., 2008). Det innebär att avloppsverkan utsätts för ett högt inflöde av 

noroviruspartiklar, speciellt under vintersäsongen. Norovirus har påvisats i både ingående och utgående 

avloppsvatten i svenska reningsverk (Nordgren et al, 2009). Exakt vad detta innebär för 

dricksvattenverken är ännu inte fullständigt klarlagt. 

Konsekvenserna av ett vattenburet utbrott är allvarliga då det innebär att ett stort antal personer är sjuka 

vilket medför en stor samhällsbelastning med kostnader av hundratals miljoner kronor som följd 

(Lindberg et al, 2011.; Lopman et al., 2004; Vas-Rådet, 2009). Det är inte enbart ekonomiska följder 

som följer efter ett utbrott, utan även ett minskat förtroende för dricksvattenproduktion. 

Flertalet andra studier har påvisat förekomst av norovirus i råvattentäkter (Maunula et al., 2012; Pérez- 

Sautu et al., 2012), men ännu är det svårt att kvantifiera virusmängden och att avgöra om det verkligen 

finns en bakgrundsnivå som är av betydelse för dricksvattenberedningen. Svårigheten ligger främst i att 

anrika vattenprover så att det går att genomföra molekylärbiologiska analyser och mäta halten av 

norovirus då en eventuell bakgrundsnivå förmodligen är väldigt låg med hänsyn till sensitiviteten i 

mätningsmetodiken. 

Norvid – norovirus i dricksvatten, är ett projekt som initierades av Görvälngruppen med syfte att 

utveckla en analysmetodik för norovirus i prover från dricksvattenverk och med dess hjälp genomföra 

en långtidsprovtagning i fyra stora dricksvattenverk i Sverige under ett års tid för att detektera samt 

kvantifiera mängden norovirus. De inkluderade vattenproducenterna är Stockholm Vatten och 

Norrvatten som båda tar sitt råvatten från Mälaren. Göteborg Vatten med Göta Älv som råvattenkälla 

och Sydvatten som under projektets tid använt sig av Ringsjön som råvattentäkt. 

Koncentrationen av norovirus i råvattnet kommer att utgöra ingångsvärden för en riskanalys med 

MRA-verktyget för att göra det möjligt att dra slutsatser om vad de halter som återfinns innebär på en 

samhällsnivå. 

Material och metoder 

Råvattenprover om 10l togs vid vattenintaget för de inkluderade vattenverken (Figur 1) varannan vecka 

i tolv månaders tid med start i september 2010 och sista provtagning i september 2011. 

En anrikningsmetod baserad på adsorption-elutions filtreringsteknik (Dalin et al., 2010.; Gilgen et al, 

1997) applicerades på samtliga prover (Figur 2). En känd mängd processkontroll av murint (mus) 

norovirus tillsattes till varje prov med förutsättningen att det kommer uppföra sig på ett liknande sätt 

som humant norovirus i filtreringsmetodiken. Fyra liter av råvattenprovet filtrerades genom ett 

glasfiber filter med porstorlek 2 µm för att avlägsna större partiklar från provet. En lösning med 

magnesiumklorid tillsattes till filtratet för att åstadkomma en flockuleringsprocess där större aggregat 

av norovirus bildas. Provet filtrerades ännu en gång genom ett cellulosa ester filter med en porstorlek 

på 0,45 µm. Filtratet kasserades och filtret tvättades med svavelsyra. Med hjälp av en basisk tvättbuffer 

backspolades filtret och ett eluat på 15 ml fångades upp som direkt neutraliserades i svavelsyra. Ett 

ultrafilter av typen mikrokoncentrator användes för att reducera volymen i provet ytterligare ner till 

200 µl vilket är en hanterbar volym för molekylärbiologiska analyser. 

Från eluatet extraherades arvsmassa med hjälp av en extraktionsrobot och ett kommersiellt kit anpassat 

speciellt för virus. Norovirus arvsmassa är i formen av enkel-strängat RNA och gjordes om till 

komplementärt DNA för att stabilt kunna förvara arvsmassa i -20 grader. 

Detektion och kvantifiering av arvsmassan från norovirus genomfördes med PCR (polymerase chain 

reaction), en molekylärbiologisk metod där den eftersökta biten arvsmassa kopieras upp i tillräckliga 

mängder för att det skall gå att erhålla en signal. Signalen från det okända provet kan jämföras med en 

spädningsserie på kända koncentrationer och således kan mängden norovirus i råvattenproverna 


eräknas. Mätningar av norovirus av två grupper genomfördes, både genogrupp ett (GI) och genogrupp 

två (GII) har gjorts. 

Detektion av musnoroviruset som tillsattes initialt genomfördes också för att ge ett mått på hur bra 

filtreringsprocessen fungerat. Även en ytterligare kontroll gjordes där mängden inhibition, dvs ämnen 

som kan störa vår analys, från humusämnen kunde mätas med en extern kontroll. 

Resultat 

En analysmetodik för norovirus i råvatten har utvecklats inom projektet och publicerats i en Svenskt 

Vatten Utveckling rapport (Dalin et al., 2010). Norovirus påvisades i alla råvattentäkter främst under 

vintersäsongen av båda genogrupperna (Tabell 1). Mängden norovirus av genogrupp två var signifikant 

högre än genogrupp ett (p

Figur 1. Provtagningspunkter. Råvatten provtogs från följande vatten: Göta Älv, råvattenkällan för 

Göteborg Vatten. Två platser i Mälaren, råvattenkällan för både Stockholm Vatten och Norrvatten samt 

Ringsjön, råvattenkällan för Sydvatten. 

Figur 2. Filtreringsprocessen. Murint norovirus (MNV-1) tillsattes till varje prov och 4,5 liter pumpades 

igenom ett glasfiberfilter med porstorlek 2 µm. Magnesiumklorid tillsattes för att flockulera provet varav 4 

liter sedan filtrerades genom ett 0,45 µm cellulosa-ester filter. Genom backspolning av filtret med en 

basisk tvättbuffert erhölls ett eluat som neutraliserades med svavelsyra. En mikrokoncentrator 

(ultrafilter) användes för att reducera volymen ytterligare från ca 15 ml ner till 200 µl. 

Tabell 1. Säsongsvariation av norovirus genogrupp ett (GI) och genogrupp två (GII). Norovirus av både 

genogrupp ett och två kunde positivt detekteras och kvantifieras från och med oktober 2010 till och med 

mitten av februari 2011, med ett positivt prov med genogrupp ett i augusti 2011. Signifikant högre halt 

av genogrupp två detekterades (p

Analysmetoder för norovirus i ytvatten (No. 2010-09). Utveckling av molekylärbiologisk metodik 

för detektion och kvantifiering i vatten och slam. Svenskt Vatten - SVU Rapport. Retrieved from 

http://www.svensktvatten.se/Vattentjanster/Dricksvatten/Forskning/Rapporter 

Gilgen, M., Germann, D., Lüthy, J., & Hübner, P. (1997). Three-step isolation method for sensitive 

detection of enterovirus, rotavirus, hepatitis A virus, and small round structured viruses in water 

samples. Int. J. Food Micro. 37(2-3), 189–199. 

Hallin, E. (in press). Norovirus i vatten. SVU-rapport in press, 2012. 

Lindberg, A., Lusua, J., & Nevhage, B. (2011). Cryptosporidium i Östersund vintern 2010/2011 (No. 

FOI-R--3376--SE). Konsekvenser och kostnader av ett stort vattenburet sjukdomsutbrott. 

Lodder, W. J., & de Roda Husman, A. M. (2005). Presence of noroviruses and other enteric viruses in 

sewage and surface waters in The Netherlands. Appl. Env. Micro., 71(3), 1453–1461. 

Lopman, B. A., Reacher, M. H., Vipond, I. B., Hill, D., Perry, C., Halladay, T., Brown, D. W., 

Edmunds W. J., & Sarangi J. (2004). Epidemiology and cost of nosocomial gastroenteritis, Avon, 

England, 2002-2003. Emerg. Infect. Dis., 10(10), 1827–1834. 

Maunula, L., Söderberg, K., Vahtera, H., Vuorilehto, V.-P., Bonsdorff, von, C.-H., Valtari, M., Laakso, 

T., & Lahti K. (2012). Presence of human noro- and adenoviruses in river and treated wastewater, 

a longitudinal study and method comparison. J. Water. Health, 10(1), 87–99. 

Miljödepartementet (2007). Klimat- och sårbarhetsutredningen (SOU 2007:60). Retrieved from 

http://www.regeringen.se/sb/d/8704/a/89334 

Nordgren, J., Matussek, A., Mattsson, A., Svensson, L., & Lindgren, P.-E. (2009). Prevalence of 

norovirus and factors influencing virus concentrations during one year in a full-scale wastewater 

treatment plant. Water Res., 43(4), 1117–1125. 

Patel, M. M., Hall, A. J., Vinjé, J., & Parashar, U. D. (2009). Noroviruses: a comprehensive review. J. 

Clin. Virol., 44(1), 1–8. 

Patel, M. M., Widdowson, M.-A., Glass, R. I., Akazawa, K., Vinjé, J., & Parashar, U. D. (2008). 

Systematic literature review of role of noroviruses in sporadic gastroenteritis. Emerg. Infect. Dis. 

14(8), 1224–1231. 

Pérez-Sautu, U., Sano, D., Guix, S., Kasimir, G., Pintó, R. M., & Bosch, A. (2012). Human norovirus 

occurrence and diversity in the Llobregat river catchment, Spain. Env. Micro., 14(2), 494–502. 

Pond, K., Rueedi, J., & Pedley S. (2004). Pathogens in drinking water sources. Centre for Public and 

Environmental Health. Microrisk report November 2004. 

Rodríguez, R. A., Thie, L., Gibbons, C. D., & Sobsey, M. D. (2012). Reducing the effects of 

environmental inhibition in quantitative real-time PCR detection of adenovirus and norovirus in 

recreational seawaters. J. Virol. Met., 181(1), 43–50. 

Rutjes, S. A., Lodder, W. J., van Leeuwen, A. D., & de Roda Husman, A. M. (2009). Detection of 

infectious rotavirus in naturally contaminated source waters for drinking water production. J. 

Appl. Micro., 107(1), 97–105. 

Seitz, S. R., Leon, J. S., Schwab, K. J., Lyon, G. M., Dowd, M., McDaniels, M., Abdulhafid, G., et al. 

(2011). Norovirus infectivity in humans and persistence in water. Appl. Env. Micro., 77(19), 

6884–6888. 

VAS-Rådet. (2009). Samhällskostnader vid störningar i dricksvattenförsörjningen (Rapport nr 7). 

WHO. (2008). Guidelines for drinking-water quality (Third edition.). Retrieved from 

http://www.who.int/water_sanitation_health/dwq/fulltext.pdf 

Wyn-Jones, A. P. & Sellwood, J. (2001). Enteric viruses in the aquatic environment. J. Appl. Micro. 

91(6), 945-962. 

Ødegaard, H., & Fiksdal, L. (2006). Optimal desinfeksjonspraksis for drikkevann. Norvar-rapport. 


Adenovirus detection in the river Glomma 

Ricardo C. Rosado*, Mette Myrmel** 

* Norwegian School of Veterinary Science, Dep of Food Safety and Infection Biology, Postboks 8146 Dep.- 

0033 Oslo, Norway Ricardo.Rosado@nvh.no 

** Mette.Myrmel@nvh.no 

Abstract. Access to safe drinking-water is an international priority, as demonstrated by the efforts put into 

the ÈInternational Decade for Action, Water for LifeŠ. The most widespread health risk associated with 

drinking water is microbial contamination by pathogenic agents, as bacteria, parasites, and viruses. 

Human adenoviruses, belonging to the genus Mastadenovirus within the family Adenoviridae, are 

responsible for gastroenteritis in young children, among other diseases, and spread by faecal-oral route. 

While their health significance is only moderate, their high resistance to UV and ubiquitous presence in 

sewage samples make them an interesting index virus to study (Rodríguez-Lázaro et al., 2011; WHO, 

2011). Water from the river Glomma, in Norway, was collected weekly between January and July 2011, at 

the inlet to the drinking water plant of the Nedre Romerike Vannverk (NRV). Samples were concentrated 

using Nanoceram® membrane filters (Argonide, USA) and reconcentrated by stirring overnight at 4ºC with 

Polyethylene glycol (PEG 8000 - 80 g/litre) and NaCl (17,5 g/ litre). All samples were extracted in the 

NucliSens®easyMAG, amplified by real-time PCR for the detection of human adenovirus (Jothikumar et 

al., 2005), and quantified using a synthetic plasmid of known sequence and molecular weight. Virus 

recovery using a sample spiked with adenovirus was calculated to 6%. Sixty-four out of 80 samples (75%) 

were positive for adenovirus, with quantifiable samples ranging from 96,5 to 1,22E4 genome equivalents 

per litre (GE / L). Only 2 weeks out of 26 had no positive samples, and a seasonal pattern can be 

observed throughout the period, which is in accordance to published data. As shown in previous 

publications (Rodríguez-Lázaro et al., 2011), the detection of adenovirus is an useful and abundant 

indicator of faecal contamination in the Glomma as well. Further work with the samples will correlate these 

results with the quantity of infectious particles, as well as the presence of other important pathogenic 

viruses. This study is part of the project VISK, ÈVirus i vatten, Skandinavisk kunskapsbankŠ, financed by 

the EU program Interreg IV A Öresund-Kattegatt-Skagerack. We would like to thank the NRV and the 

Veterinærinstituttet for help in the collection of samples, and the Veterinærinstituttet for assistance in 

processing the samples. 

References 

Jothikumar, N., Cromeans, T. L., Hill, V. R., Lu, X., Sobsey, M. D., & Erdman, D. D. (2005). Quantitative real-time 

PCR assays for detection of human adenoviruses and identification of serotypes 40 and 41. Applied and 

environmental microbiology, 71(6), 3131-6. doi:10.1128/AEM.71.6.3131-3136.2005 

Rodríguez-Lázaro, D., Cook, N., Ruggeri, F. M., Sellwood, J., Nasser, A., Nascimento, M. S. J., D••Agostino, M., et 

al. (2011). Virus hazards from food, water and other contaminated environments. FEMS Microbiology Reviews, 

n/a-n/a. doi:10.1111/j.1574-6976.2011.00306.x 

WHO. (2011). WHO guidelines for drinking-water quality. (World Health Organisation, Ed.) (4th ed., Vol. 38, p. 

541). Geneva, Switzerland: World Health Organisation. Retrieved from 

http://www.who.int/water_sanitation_health/publications/2011/dwq_guidelines/en/index.html 


Ultrafiltration – an independent microbiological barrier at 

Lackarebäck water treatment plant, Göteborg Vatten 

Helena Almqvist*, Henrik Rydberg*, Olof Bergstedt* , **, Inger Kjellberg* 

* Göteborg Vatten, Box 123, SE-424 23 Angered, Sweden, helena.almqvist@vatten.goteborg.se 

** also Department of Civil and Environmental Engineering, Chalmers University of Technology 

SE-412 96 Gothenburg, Sweden 

Abstract. The most severe risks of the water supply in Gothenburg were identified as the risk for water 

borne diseases, and major interruption of the water delivery. To handle these risks several projects were 

started at Göteborg Vatten, of which one concerned ultrafiltration (UF) at Lackarebäck water treatment 

plant. The integrity testing of the membranes down to virus size ~20-25 nanometers is a key challenge. 

High numbers of small particles are necessary to be able to measure a 4 log reduction over the 

membranes. In opposite to viruses, naturally occurring phages (~50 nm), so called virus-like particles 

(VLPs), exist in high densities in the feed water. However, since ultrafiltration is based on size-exclusion it 

does not matter if monitored particles are viruses or not. Therefore VLPs are suitable as indicators of 

membrane integrity. During normal operation of the UF pilot plant, the membrane has so far been intact, 

and the log removal of VLPs has reached 3.8-5.8 and the log removal of cells were in the interval 3.0-3.8. 

The two challenge tests performed to verify the barrier criteria resulted in the 4 log removal of coli phages 

(φX-174) and 5-6 log removal of E. coli. Chemical precipitation in combination with UF seems to be a 

powerful barrier towards waterborne disease. The barrier effects of the existing process barriers 

(precipitation and disinfection by chlorination) depend on each other. In cases of suboptimal operation 

conditions (e.g. problems in the precipitation process), the barrier effect will be affected in a negative way. 

Since UF is a “stand alone” process, based on size exclusion, this makes it an independent microbiological 

barrier. Moreover, the ≥ 4 log virus removals on clean membranes (independently of chemical 

precipitation) aiming at ensuring the virus removal capability of the membrane itself – is a very important 

condition for the UF being considered an independent barrier. A key challenge however, is the integrity 

testing methods and the continuous monitoring of the UF membranes, which will be prevailed by the 

described VLP tests, by particle counting and/or the AIT. 

Introduction and background 

Since the late 1980 th there has been an ongoing process in Gothenburg concerning various risks for the 

drinking water system – not least regarding quantities, the delivery system, and the water quality. A lot of 

work has been put into risk analysis, and action plans were made to meet the identified risks. To a large 

extent this was done based on work and research at Chalmers University of Technology – or has been fed 

back as input in their ongoing research. Along with this work, future goals for the drinking water system 

were established together with the responsible politicians in Gothenburg, which was described at the 

annual meeting at The Swedish Water & Wastewater Association (Vattenstämman) in Stockholm 16 th 

May 2012 (Roos, B., Dahlman Ek, C., Sander, A.). 

The most severe risks of the water supply in Gothenburg were identified as the risk for water borne 

diseases, and major interruption of the water delivery. To handle these risks several projects were started 

at Göteborg Vatten, of which one concerned ultrafiltration (UF) at Lackarebäck water treatment plant 

(WTP). 

Objectives 

The objective of this paper was to describe the procedures at Göteborg Vatten in order to verify the UF as 

a microbiological barrier. 


A brief description of the UF plant 

Lackarebäck water treatment plant – before extension with UF 

The water treatment process at Lackarebäck WTP is based on surface water from the Göta river (Göta 

älv), which is pumped and stored in the Delsjö lakes before it is taken in to the WTP. The raw water is 

conventionally treated by precipitation with aluminium sulphate, via sedimentation to GAC filters. The 

drinking water quality is finally adjusted by addition of lime, sodium hydroxide, and desinfection by 

chlorine gas and chlorine dioxide, see Figure 1. 

Raw 

water 

Al 2 SO 4 

Precipitation/ 

sedimentation 

Filtration 

GAC-filters 

Figure 1 A schematic process schedule of the Lackarebäck WTP 

Ultrafilters at Lackarebäck water treatment plant 

The main purpose for adding the UF step is to improve the microbiological barrier at the WTP. The UF 

treatment step is located after the GAC filters – as the very last treatment step, see Figure 1. At the 

procurement of the UF plant, the criteria for assuring the microbial barrier were established to ≥ 4 log 

removal of viruses, and ≥ 6 log removal of protozoa (Heinicke et al., 2011). To evaluate the UF 

tenders/various technical solutions, three main conditions were formulated, and evaluated: 

1. There should be ≥ 4 log virus removals on clean membranes, independently of chemical 

precipitation. The purpose of this condition was to ensure the virus removal capability of the 

membrane itself – a very important condition for the UF being considered an independent 

barrier. 

In absence of certifying test methods, we here by referred to a test protocol for a bench-scale test 

according to NSFs Environmental Technology Verification Protocol, Chapter 2, section 16, 

Microbial removal (February 2005 05/9205/EPADWCTR). 

2. The tenders should describe constructive procedures for the verification of that the delivered 

membrane modules keep the promised quality. 

3. The tenders should describe constructive procedures for continuous integrity testing of the UF 

plant during full scale operation. 

The procurement of the UF plant at the Lackarebäck WTP is described thoroughly in Heinicke et al 

(2011). 

UF 

Lime, NaOH 

Chlorine 

Drinking water 

adjustment 

Drinking 

water 

The UF pilot plant 

The first part of the UF delivery was the UF pilot plant that has been in operation since December 2010. 

The UF pilot plant is a small size copy of the full-scale plant, consisting of one single membrane module 

of the type XIGA SXL 225 with the capacity 4.1 m 3 /h (100 m 3 /d). The UF pilot plant is useful for various 

purposes. So far we have been testing different cleaning and rinsing strategies, the membrane integrity 

(using different methods), and we have been observing the UF in operation – e.g. the development of 

TMP/permeability vs. production capacity. The feed water for the UF pilot plant is treated water after 

GAC filters – the same water quality as designed for the full scale. 

The building of the full scale UF plant 

The building of the UF step is scheduled from June 2012 till the summer 2016. To have room enough for 

the UF step at Lackarebäck WTP, the water works had to be enlarged. After some considerations this was 


decided to be done by adding two new extensions – the North and the South extension. Each extension 

will contain half the UF plant as well as four new GAC filters (in total 8 new GAC filters). When 

finished, the Lackarebäck WTP will have an increased production capacity of 40 % (186 000 m 3 /d – due 

to larger GAC filter area) and a significantly improved microbiological barrier. In Table 1 some “hard 

facts” about the UF plant are presented. 

Table 1 Hard facts about the UF plant at Lackarebäck WTP 

Maximum capacity 186 000 m 3 /d 

Contractor Läckeby Water, Purac 

Membrane delivery Pentair X-Flow 

Filtration mode Dead end filtration 

Pore-size 20-25 nm 

Head-loss (UF pilot plant) 0.2-0.25 bar 

Design flux 102 l/m 2 ,h 

Methods for integrity testing and continuous monitoring of UF membranes 

Described below is a summary of methods applied by Göteborg Vatten, which does not aim to be an 

exhaustive overview of ultrafilter integrity testing methods (such as presented in for example EPA 

815:2005 Membrane Filtration Guidance Manual). 

General considerations 

Integrity testing of ultrafilter membranes, down to particle size ~20-25 nanometers, is a key challenge that 

should ultimately verify the level of virus removal. Hence, the prerequisite for successful monitoring of 

removal is the ability to detect low concentrations of very small particles. Since ultrafiltration is based on 

size-exclusion, removal of larger microbial agents could generally be assumed to be at least as effective 

compared to removal of smaller particles. Impaired integrity could occur by two main causes: 

A. Ultrafilter fiber or connector failures by breakage 

B. Ultrafilter fiber failure due to pore size distribution increase 

Table 2 Considerations important for determining ultrafilter integrity testing strategy. 

A. Fiber or connector breakage B. Pore size increase 

Consequence Proportion of feed not treated, 

independent of particle size. 

Removal efficiency decreased 

equally concerning viruses, bacteria, 

and parasites. 

Proportion of feed not treated, 

dependent on particle size. 

Removal efficiency decreased 

starting with smallest viruses. 

Failure time-line Instant process. If correct pore size on module 

delivery, increased pore size 

distribution is assumed to be a 

slow process. 

Monitoring strategy Continuous, preferably on-line. Discrete full scale sampling. 

Alternatively pilot scale challenge 

test. 

Methods for integrity testing 

Fluorescence microscopy 

Pilot plant samples were examined according to the protocol described by Patel et al (2007). Naturally 

occurring phages (virus-like particles) and bacteria were pre-concentrated on 0.02-µm aluminium oxide 

filters (Anodisc 25, Whatman) and stained by the sensitive DNA dye SYBR Green I (Molecular Probes- 


Invitrogen). After mounting on slides, samples were examined by fluorescence microscopy (Zeiss 

AxioScope.A1) using appropriate equipment for blue excitation/green emission. With these rapid 

procedures valuable parameters for testing membrane integrity were obtained within an hour. 

Virus-like particles (VLPs), dominated by harmless naturally occurring bacterial viruses, phages (~50 

nm, dsDNA). These phages can be regarded as the biospheres most abundant biological particles and 

exist in very high densities in surface waters as well as after conventional treatment. By concentration of 

a 50 ml water sample the practical level of detection was estimated to approximately 100 VLPs/ml. The 

abundance and small size of VLPs should make them suitable for full scale direct integrity testing. As an 

indicator of virus removal this would include control of ≥ 4 log removal as well as rapid detection of 

failures such as fiber breakage and pore size increase. 

Bacterial total counts, dominated by bacteria of surface water origin and/or GAC filter regrowth (~1 

µm). By concentration of a 100 ml water sample the practical level of detection was estimated to 

approximately 100 cells/ml. These bacteria generally do not exist in densities high enough to monitor 

more than 4 log removal, and could not easily detect pore size increase. However, total bacterial count 

was expected to be far more sensitive than for example turbidity, and also a means of simultaneously 

monitoring potential permeate regrowth. 

As an alternative to sample concentration and microscopy, flow cytometry (Partec Cube8) was applied, 

for detection of naturally occurring auto fluorescent algae. The densities of these particles in feed water 

were rarely high enough to accomplish effective integrity testing of more than 2 log. 

Microbiological standard methods 

Integrity monitoring by culturing feed water bacteria and parasites are generally not possible in full scale 

due to low densities. However, examination of full scale ultrafilter modules could easily be performed in 

pilot scale challenge tests by use of microbiological standard methods. 

Somatic coliphages, are bacterial viruses, such as the reference phage φX-174 (26-32 nm), infecting 

Escherichia coli. Analyses were performed according to ISO 10705-2:2000 Water quality – Detection and 

enumeration of bacteriophages. To achieve a practical level of detection of 1 phage/100 ml the method 

was modified by procedures in EPA Method 1602. In pilot scale challenge tests this indicator of virus 

removal could easily control ≥ 4 log removal, as well as detection of failures such as fiber breakage and 

pore size increase. 

Escherichia coli, are bacteria naturally occurring in human faeces (~1 µm). Analyses were performed by 

Colilert-18 ® (IDEXX) according to ISO/DIS 9308-2 Water quality – Enumeration of Escherichia coli and 

coliform bacteria which yielded a level of detection of 1 E.coli/100 ml. Although E.coli should be 

analysed and evaluated with great care in drinking water treatment, it is a valuable alternative indicator 

for both bacteria and parasite removal over ultrafiltration. In pilot scale challenge tests this indicator 

could easily control ≥ 6 log removal, as well as detection of failures such as fiber breakage, but not pore 

size increase. 

On-line monitoring 

Integrity tests could not effectively be monitored by regular turbidimeters, since feed water turbidity was 

10 5 /ml 1 µm biological particles. 


• The fact that biological particles, such as ~1 µm bacteria, generally scatters light in a way that 

they appear approximately half their actual size and therefore would not be detected by many 

particle counters specified to 1 µm. 

• Ratio between feed water particle densities (>10 5 /ml) and expected limit of detection (~10/ml), 

where detector noise was expected to increase with decreasing particle size. 

In future full scale, these particle counts were expected to monitor approximately 4 log on-line integrity 

of ultrafilter failure due to breakage. 

Air integrity tests, were performed in pilot scale by on-line discrete pressure hold tests according to the 

XIGA TM concept (Pentair X-flow). The test is based on the phenomenon that air will not pass through 

wetted membrane pores without a certain pressure, which is related to pore size. By examining pressure 

decay over the membrane one could ultimately detect one broken fiber per 10,000 in the module. 

Challenge tests 

Ultrafilter challenge tests were performed in pilot scale by feed water spiking with bacteriophages as a 

substitute for viruses, and E. coli as a substitute for bacteria and parasites. 

φX-174 (ATCC 13706-B1), was propagated and analysed according to a modified procedure generally 

following ISO 10705-2:2000 Annex C. This yielded phage suspensions with titres exceeding 10 9 /ml used 

for feed water addition. 

E. coli (ATCC 700078, WG5), was cultured according to a procedure generally following ISO 10705- 

2:2000. This yielded E. coli suspensions exceeding 10 8 /ml used for feed water addition. Challenge test 

samples were analysed by Colilert-18 ® (IDEXX). 

The data on removal efficiency of these short term tests could be calculated in a couple of different ways. 

In this paper we used peak to peak log removal efficiency (LRV) during challenge test, as defined in EPA 

Membrane Filtration Guidance Manual, where 

LRV = log10 (feed concentration) – log10 (filtrate concentration) 

Preliminary full-scale operational monitoring strategy 

A prerequisite for guaranteeing membrane integrity, concerning virus removal, is a verified membrane 

pore size distribution on module delivery. 

Table 3 Proposed operational integrity testing. 

Method Frequency Aim 

Particle counter: 

0.2 – 2 µm on every UF-skid 

Virus-Like particles: 

every UF-skid 

Virus-Like particles: 

each half of WTP 

Air Integrity Test: 

every UF-skid 


Continuous Detect fast and major failures such as fibre 

breaks/leaking connectors: 

verifies ~ 4log removal on skid level 

Once a week Detect slow pore-size failures: 

verifies > 4 log removal on skid level 

Weekdays Monitor overall virus barrier: 

verifies > 4 log removal on WTP level 

Weekends 

(every day?) 

Automated detection of fibre breaks. 

(high frequency could negatively stress fibers) 

Since commissioning in December 2010 the UF pilot plant has, more or less, been operating on the design 

flux 102 l/m 2 ,h with a mean TMP of 0,26 bar (depends of temperatures), and a permeability variation 

between 520 and 610 l/m 2 ·h·TMP(bar)/20ºC), (depends on water quality and cleaning procedure). Once 

an hour the membrane is backwashed with permeate during 35 s. Once a day the membranes are washed 


in a chemically enhanced backwash sequence (CEB) – using all, or some of the chemicals: sodium 

hydroxide, sodium hypochlorite, and sulphuric acid. 

Integrity during normal operation 

Our main interest has been the integrity of the membranes, and the ability of fulfilling the barrier criteria. 

During normal operation the membrane has so far been intact, and the log removal of VLPs has reached 

3.8-5.8 and the log removal of cells were in the interval 3.0-3.8, see Figure 2. 

Figure 2 During normal operation of the UF pilot plant, the log removal of VLPs was 3.8-5.8 and the log 

removal of cells showed 3.0-3.8. 

Challenge tests on the UF pilot plant 

The two challenge tests performed to verify the barrier criteria resulted in the 4 log removal of coli 

phages (φX-174) (see Figure 3) and 5-6 log removal of E. coli (see Figure 4). The 5-6 log removal of E. 

coli bacteria was interpreted as fulfilling the 6 log removal criteria for removal of protozoa, since 

protozoa are about 10 times larger than the tested model organism. 

Number of coli phages φX-174 

1,00E+07 

1,00E+06 

1,00E+05 

1,00E+04 

1,00E+03 

1,00E+02 

2011-07-26 

1,00E+10 

1,00E+08 

1,00E+06 

1,00E+04 

1,00E+02 

1,00E+00 

Total Cells/ml Feed VLP/ml Feed VLP & Total Cells/ml Permeate 

2011-08-26 

2011-09-26 

2011-10-26 

2011-11-26 

2011-12-26 

Feed water Permeate 

1 10 100 1000 10000 

Time (min) 

Figure 3 Challenge test resulting in the 4 log removal of coli phages (virus-sized ≈ 26-32 nm) 


Number of E. coli 

1,00E+08 

1,00E+06 

1,00E+04 

1,00E+02 

1,00E+00 

1 10 100 1000 

Figure 4 Challenge test resulting in the 5-6 log removal of E. coli (bacteria size ≈ 1m) 

Results from the AIT at the UF pilot plant 

The Air Integrity Test (AIT) is performed daily and automatically on the pilot plant. If the airflow 

through the membranes is less than 2 l/h, the membrane is accepted intact. So far, all measurements have 

been far from that limit. 

UF an independent microbiological barrier 

Chemical precipitation in combination with UF seems to be a powerful barrier towards waterborne 

disease (Persson et al, 2005). The barrier effects of the existing process barriers (precipitation and 

disinfection by chlorination) depend on each other. During suboptimal operation conditions (for example 

problems in the precipitation process), the barrier effect will be affected negatively. Ultrafiltration 

however, is a “stand alone” process based on size exclusion (at virus size) which makes it an independent 

microbiological barrier. When the UF step is installed, situations with suboptimal operation conditions in 

the conventional treatment, may actually lead to even higher exclusion rates, since high turbidity and rest 

flocks may improve the microbial log reduction. In view of these facts – could not today’s treatment 

process steps, previous to UF, be replaced by the UF plant only? However, the answer to this is no – high 

turbidity and rest flocks may improve the microbial log reduction, but it might also increase the need for 

cleaning/rinsing of the membranes, the energy consumption would increase, and there would be a higher 

risk for permanently increased TMP as well. 

A key challenge is the integrity testing and continuous monitoring of the UF membranes. If membrane 

fibers or other parts break – e.g. the connectors in between the membrane modules in the pressure vessels 

– there will be short-cuts of the barrier. The integrity testing and continuous monitoring of the UF 

membranes will be prevailed by VLP tests, AIT, and monitoring by particle counters. In the full scale UF 

plant there will be 2 176 modules, containing 23 000 000 membrane fibers. Certainly, there will be a true 

challenge to keep track of this stack of “spaghetti”. In beforehand we do not exactly know how many 

fiber breaks that have occurred when we will be able to actually monitor a decreased barrier effect in the 

overall permeate flow. Never-the-less the UF full-scale plant will enhance the microbiological barrier at 

the Lackarebäck WTP – fiber breaks occurring or not. 

Conclusions 

Feed water Permeate 

Time (min) 

Are ultrafiltration membranes a reliable microbiological barrier? The criteria for evaluating the 

microbial barrier of the UF plant were established to ≥ 4 log removal of viruses, and ≥ 6 log removal of 

protozoa. During procurement of the UF plant these criteria were assessed thoroughly. Until November 

2014 – with no full scale plant in place, we have to rely on the results from the UF pilot plant – which 

however show encouraging results. Challenge tests and VLP results show a base line that confirm that the 

UF membranes achieve ≥ 4 log removal of viruses, and ≥ 6 log removal of protozoa. 


Chemical precipitation in combination with UF seems to be a powerful barrier towards waterborne 

disease. The barrier effects of the existing process barriers (precipitation and disinfection by chlorination) 

depend on each other. In cases of suboptimal operation conditions (e.g. problems in the precipitation 

process), the barrier effect will be affected in a negative way. Since UF is a “stand alone” process, based 

on size exclusion, this makes it an independent microbiological barrier. Moreover, the ≥ 4 log virus 

removals on clean membranes (independently of chemical precipitation) aiming at ensuring the virus 

removal capability of the membrane itself – is a very important condition for the UF being considered an 

independent barrier. A key challenge however, is the integrity testing methods and the continuous 

monitoring of the UF membranes, which will be prevailed by the described VLP tests, by particle 

counting and/or the AIT. 

References 

EPA Method 1602:2001. Male-specific (F+) and Somatic Coliphage in Water by Single Agar Layer (SAL) 

procedure. 

EPA 815:2005 Membrane Filtration Guidance Manual. 

Heinicke, G., Lindstedt, C., Viklund, P., Almqvist, H., Bergstedt, O. (2011). Upphandling av ultrafilter – en handbok 

för vattenverken. Rapport Svenskt Vatten Utveckling 2011-05. 

ISO 10705-2:2000. Water quality – Detection and enumeration of bacteriophages. Part 2: Enumeration of somatic 

coliphages. 

ISO/DIS 9308-2. Water quality – Enumeration of Escherichia coli and coliform bacteria. Part 2: Most probable 

number method. 

Patel, A et al. (2007). Virus and prokaryote enumeration from planktonic aquatic environments by epifluorescence 

microscopy with SYBR Green I. Nature Protocols. Vol.2 No.2, 269-277. 

Persson, F., Heinicke, G., Hedberg, T., Bergstedt, O., Wångsell, O., Rydberg, H., Kjellberg, I., Kristenson, S-E. 

(2005). Mikrobiologiska barriärer i vattenrening. Svenskt Vatten. Rapport VA-forsk 2005-17. 

Roos, B., Dalman Eek, C., Sander, A. (2012). Speech at the Water Conference (Vattenstämman) at the annual 

meeting at The Swedish Water & Wastewater Association in Stockholm 16 th May 2012. “Så skapade vi en 

politisk beslutsprocess kring hållbara vattentjänster”. 


Water quality modelling, monitoring and microbial source 

tracking for microbial risk assessment of a drinking water 

source 

Ekaterina Sokolova*, Thomas J.R. Pettersson**, Johan Åström***, Olof Bergstedt****, 

Inger Kjellberg***** and Malte Hermansson****** 

* Water Environment Technology, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden, 

ekaterina.sokolova@chalmers.se 

** Water Environment Technology, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden, 

thomas.pettersson@chalmers.se 

*** Tyréns AB, Lilla Badhusgatan 2, SE-411 21 Gothenburg, Sweden, johan.astrom@tyrens.se 

**** Gothenburg Water, City of Gothenburg, Box 123, SE-424 23 Angered, Sweden, 

olof.bergstedt@vatten.goteborg.se 

***** Gothenburg Water, City of Gothenburg, Box 123, SE-424 23 Angered, Sweden, 

inger.kjellberg@vatten.goteborg.se 

****** Department of Cell and Molecular Biology, Microbiology, University of Gothenburg, SE-405 30 

Gothenburg, Sweden, malte.hermansson@cmb.gu.se 

Abstract. To prevent waterborne disease outbreaks, mitigation of faecal contamination of drinking water 

sources and sufficient treatment of water at the drinking water treatment plant (DWTP) are required. The 

aim of this study was to combine and apply several tools to investigate the raw water quality and determine 

the risk for waterborne infections in a drinking water source for the cities of Mölndal and Gothenburg in 

Sweden, Lake Rådasjön. 

To identify the major contamination sources around the lake and their contribution to the faecal 

contamination at the water intakes of DWTPs, monitoring of faecal indicators and pathogens was 

combined with microbial source tracking and water quality modelling. The microbial source tracking was 

performed to determine the human or ruminant origin of faecal contamination using host-specific 

Bacteroidales genetic markers. The decay of these genetic markers in relation to the decay of traditional 

faecal indicators in water environment was investigated in outdoor microcosm trials performed in different 

seasons. Using measured concentrations of Bacteroidales genetic markers the pathogen (norovirus and 

Cryptosporidium) concentrations in faecal contamination sources around the lake were estimated for 

endemic and epidemic conditions. Afterwards, the fate and transport of faecal indicators and pathogens 

within the lake were simulated using a three-dimensional coupled hydrodynamic and microbiological 

model, which was calibrated based on the decay data from the microcosm trials. Based on the obtained 

results a microbial risk assessment of a conventional DWTP was conducted using two different 

approaches – optimal disinfection practices (ODP) and quantitative microbial risk assessment (QMRA). 

The results showed that the on-site sewers were the source that contributed the most to the pathogen 

concentrations at the water intakes under both endemic and epidemic conditions. The results from both the 

ODP and QMRA risk assessments indicated that the barrier efficiency against Cryptosporidium and 

possibly viruses may be too low at a conventional DWTP. This study demonstrated how different 

approaches and tools can be applied to evaluate the risks for waterborne infections and prioritise 

mitigation measures related to faecal contamination of surface drinking water sources. 

Introduction 

The faecal contamination of drinking water sources can lead to waterborne disease outbreaks among 

consumers, as recently happened in the Swedish cities Östersund and Skellefteå in 2010/2011 

(Skellefteå Municipality 2011, SMI 2011). To prevent waterborne disease outbreaks, mitigation of faecal 

contamination of drinking water sources and sufficient treatment at the drinking water treatment plant 

(DWTP) are required. 


To mitigate faecal contamination of drinking water sources, knowledge on the faecal sources in the 

catchment and their contribution to the contamination at the water intakes is required. Faecal 

contamination can enter a drinking water source through wastewater discharges from various sources and 

surface runoff. Therefore, it may be difficult to estimate the relative contribution from different sources to 

the total contamination at the water intakes. Moreover, the presence of pathogens from faecal 

contamination in a water source may remain undetected due to limitations of the commonly used 

monitoring techniques (Brookes et al. 2005). 

To ensure sufficient drinking water treatment in terms of pathogen removal at the DWTP, a microbial 

risk assessment needs to be performed. Microbial risk assessment is mainly based on the information 

about the quality of the raw water and the performance of the treatment steps at the DWTP. A correct 

representation of pathogen concentrations in the raw water is crucial for estimation of the infection risks 

among consumers. However, the variations in the pathogen concentrations in the raw water over time, 

caused by the variations in the hydrodynamic conditions and the level of infection in different hosts, are 

often unknown or poorly understood. 

This article provides a short overview of the work performed within a project “Evaluation of the 

microbial risks in a relatively unaffected surface drinking water source: water quality modelling, decay 

trials and microbial source tracking in Lake Rådasjön” (Åström et al. 2011). The aim of this project was 

to evaluate and implement several tools to determine the risks for waterborne infections posed by 

different contamination sources. The microbial water quality in a drinking water source for the cities of 

Mölndal and Gothenburg in Sweden, Lake Rådasjön, was investigated using monitoring, microbial source 

tracking, a microcosm study of the faecal indicator decay in raw water and coupled hydrodynamic and 

microbiological modelling. Based on the obtained results a microbial risk assessment of a conventional 

DWTP was conducted using two different approaches – optimal disinfection practices and quantitative 

microbial risk assessment. 

Material and Methods 

Lake Rådasjön (Figure 1) is located on the west coast of Sweden and constitutes the main water source 

for the city of Mölndal (60 000 consumers) and a reserve water supply for the city of Gothenburg 

(500 000 consumers). The surface area of the lake is approximately 2.0 km 2 and the maximum water 

depth is 23 m. The main inflow to the lake is the river Mölndalsån with a water flow in the range from 1 

to 20 m 3 /s. The river Mölndalsån enters the lake in the southeast and drains the lake in the west to Lake 

Stensjön (Figure 1). The water intakes for the cities of Gothenburg and Mölndal are located in the northwestern 

part of the lake at 8 m and 15 m depth respectively (Figure 1). Lake Rådasjön is potentially 

subjected to faecal contamination from various sources located in the catchment of the lake. In terms of 

the risks for waterborne disease outbreaks the sources of human and ruminant faecal contamination are 

assumed to be the most relevant. Some examples of such sources in the catchment of Lake Rådasjön are: 

discharges from on-site sewers, emergency sewer overflows, surface runoff from urban areas and grazing 

areas for cattle and horses. 

A monitoring program commenced in 2008 to identify the major contamination sources around the 

lake and to evaluate the water quality at the water intakes. The program included analyses of various 

faecal indicators in grab samples repeatedly collected at the contamination sources and the water intakes, 

as well as at-line monitoring (measurements once a day) of E. coli at the water intakes using Colifast® 

equipment (www.colifast.no). Moreover, analyses of Giardia and Cryptosporidium were performed on 

samples collected regularly at the water intakes and sporadically at a contamination source close to the 

water intakes. 

To determine the human or ruminant origin of the faecal discharges from the contamination sources 

around the lake, a microbial source tracking method using host-specific Bacteroidales genetic markers 

was applied. The concentrations of human (BacH) and ruminant (BacR) Bacteroidales 16S rRNA 

markers in the samples collected at the contamination sources and the water intakes were analysed using 

qPCR assays (Reischer et al. 2006, Reischer et al. 2007). To account for the uncertainties and provide a 

reliability measure for interpreting microbial source tracking data, a Bayesian approach was used to 

combine the Bacteroidales qPCR assay performances with expert judgements based on the knowledge of 

the study area (Åström et al. 2012). 


The decay of human and ruminant Bacteroidales markers in relation to the decay of traditional faecal 

indicators in the conditions of Lake Rådasjön was investigated in outdoor microcosm trials. Microcosm 

trials were conducted in March, August and November 2010 in order to capture the varying light and 

temperature conditions in different seasons. Two microcosms were constructed, one exposed to natural 

light and another protected from light. Microcosms were constructed in aquaria filled with raw water 

from Lake Rådasjön and inoculated with untreated wastewater and bovine faecal matter. The 

concentrations of Bacteroidales markers, total coliforms, E. coli, intestinal enterococci and somatic 

coliphages were analysed during two-week periods to follow the decay of faecal indicators (Sokolova et 

al. 2012a). 

To quantify the contribution from different contamination sources to the microbial concentrations at 

the water intakes, the decay and transport of E. coli and pathogens within the lake were simulated using a 

microbiological model (ECO Lab by DHI) coupled to a three-dimensional hydrodynamic model (MIKE 3 

by DHI). The input data for the model regarding the E. coli concentrations in the contamination sources 

around the lake were obtained from the monitoring campaign. The possible pathogen (Cryptosporidium, 

norovirus and E. coli O157/H7) concentrations in the contamination sources around the lake were 

estimated for endemic and epidemic conditions using the obtained microbial source tracking data 

(Sokolova et al. 2012b). The microbiological model was calibrated using the faecal indicator decay data 

from the microcosm experiment. The modelling results regarding the E. coli concentrations at the water 

intakes were validated using the measured data. 

The results of monitoring and modelling provided raw water quality data needed to assess the health 

risks for consumers. A risk assessment was performed using the optimum disinfection practices (ODP) 

and quantitative microbial risk assessment (QMRA) tools (a description of these tools is available at 

www.svensktvatten.se). The ODP tool requires historical data on faecal indicator concentrations in raw 

water, while QMRA is based on pathogen concentrations in a water source. 

Figure 1 Map of Lake Rådasjön. The circle indicates the location of the water intakes. The dots represent 

the location of the major faecal contamination sources: on-site sewers (3 and 7), untreated stormwater 

(18), cattle grazing area (17) and emergency sewer overflow (P). The arrows represent the inflow to the 

lake from the river Mölndalsån and the outflow from the lake. 


Results and Discussion 

The monitoring campaign in combination with the microbial source tracking helped to identify the 

major contamination sources, which included the discharges from the on-site sewers (Figure 1, sites 3 and 

7), urban stormwater runoff (Figure 1, site 18), the cattle grazing area (Figure 1, site 17), the emergency 

sewer overflow (Figure 1, site P), and the main inflow to the lake – the river Mölndalsån (Figure 1). 

The at-line monitoring of the E. coli concentrations at the water intakes corresponded well with the 

laboratory analyses of the E. coli concentrations in grab samples. At-line monitoring proved useful to 

relatively fast provide an overview of the raw water quality and its variations. The pathogens Giardia and 

Cryptosporidium were detected in 2 and 4 samples, respectively, out of 61 samples collected at the water 

intakes during 2005 – 2011. Giardia was also detected in one out of 12 samples collected during 2010 – 

2011 in the stream contaminated by on-site sewers (Figure 1, site 3). 

The results from the coupled hydrodynamic and microbiological modelling corresponded well with 

the observed E. coli concentrations at the water intakes (Figure 2). Both monitoring and modelling 

indicated that the microbial water quality can vary strongly over time and that the highest levels of faecal 

contamination at the water intakes can be expected in autumn, winter and early spring (Figure 2). 

Based on the modelling results we can conclude that under endemic conditions the stream 

contaminated by on-site sewers contributed the most to the norovirus concentrations at the water intakes 

in Lake Rådasjön, while the cattle grazing area was the main contributor to the Cryptosporidium 

concentrations. Under epidemic conditions the stream contaminated by on-site sewers contributed the 

most to both norovirus and Cryptosporidium concentrations at the water intakes. 

Integrating microbial source tracking with coupled hydrodynamic and microbiological modelling 

proved to be useful to evaluate the contribution of different contamination sources to the pathogen 

concentrations at the water intakes. Moreover, the modelling approach enables testing various scenarios, 

for example, future or worst-case conditions and alternative locations of the water intakes or 

contamination sources. 

The results from both the ODP and QMRA risk assessments indicated that the barrier efficiency 

against Cryptosporidium and possibly viruses may be too low at a conventional DWTP. Although the 

QMRA tool was more demanding than the ODP tool in terms of input data, it presented an opportunity to 

test different scenarios and investigate the effects of the infection rate and the location of the 

contamination sources around the lake on the health risk. 

This study demonstrated how different approaches and tools can be applied to evaluate the risks for 

waterborne infections and prioritise mitigation measures related to faecal contamination of surface 

drinking water sources. 

Figure 2 E. coli concentrations at the 8 m (black colour) and 15 m (grey colour) water intakes during the 

year 2008: comparison of the modelling results (line) with observed E. coli concentrations (dots). 


Acknowledgements 

This research was funded by the Swedish Water and Wastewater Association (Svenskt Vatten); the 

Graduate School on Environment and Health (Miljö och Hälsa Forskarskolan) at Chalmers University of 

Technology and the University of Gothenburg, Sweden; the EU project VISK (Interreg IV A program); 

the EU project TECHNEAU; the city of Gothenburg; the city of Mölndal; the Härryda Municipality; 

Region Västra Götaland (GR); the Administrative Board in Västra Götaland County (Länsstyrelsen 

Västra Götalands län); the Water Management Association for the river Göta älv (Göta älvs 

Vattenvårdsförbund). 

References 

Åström, J., Bergstedt, O., Sokolova, E., Kjellberg, I., Pettersson, T.J.R., Borell Lövstedt, C., Karlsson, A. & 

Wennberg, C. (2011). Evaluation of the microbial risks in a relatively unaffected surface drinking water 

source: water quality modelling, decay trials and microbial source tracking in Lake Rådasjön (In Swedish: 

"Värdering av risker för en relativt opåverkad ytvattentäkt: Modellering av Rådasjön med stöd av 

inaktiveringsstudier och mikrobiell källspårning"). Svenskt Vatten Utveckling, Stockholm. 

http://vav.griffel.net/filer/Rapport_2011-18 

Åström, J., Pettersson, T.J.R., Reischer, G.H. & Hermansson, M. (2012). A Bayesian Monte Carlo approach to 

combine Bacteroidales qPCR analyses with expert judgements for faecal source tracking in surface waters. 

Manuscript. 

Brookes, J.D., Hipsey, M.R., Burch, M.D., Linden, L.G., Ferguson, C.M. & Antenucci, J.P. (2005). Relative value of 

surrogate indicators for detecting pathogens in lakes and reservoirs. Environ. Sci. Technol. 39(22), 8614- 

8621. 

Reischer, G.H., Kasper, D.C., Steinborn, R., Mach, R.L. & Farnleitner, A.H. (2006). Quantitative PCR method for 

sensitive detection of ruminant fecal pollution in freshwater and evaluation of this method in alpine karstic 

regions. Appl. Environ. Microbiol. 72(8), 5610-5614. 

Reischer, G.H., Kasper, D.C., Steinborn, R., Farnleitner, A.H. & Mach, R.L. (2007). A quantitative real-time PCR 

assay for the highly sensitive and specific detection of human faecal influence in spring water from a large 

alpine catchment area. Lett. Appl. Microbiol. 44(4), 351-356. 

Skellefteå Municipality (2011). Discharges of wastewater caused Cryptosporidium infections: Report from the 

Department of Construction and Environment, Skellefteå Municipality on their work and conclusions. (In 

Swedish: "Utsläpp av avloppsvatten orsakade cryptosporidiesmittan - redovisning av bygg- och 

miljökontorets arbete och slutsatser"). Department of Construction and Environment, Skellefteå 

Municipality. 

http://www.skelleftea.se/Bygg%20och%20miljokontoret/Innehallssidor/Bifogat/Slutrapport%20bygg- 

%20och%20milj%C3%B6kontoret.pdf 

SMI (2011). Cryptosporidium in Östersund: The work of the Swedish Institute for Communicable Disease Control 

with the waterborne disease outbreak in Östersund in 2010-2011 (in Swedish: "Cryptosporidium i 

Östersund: Smittskyddsinstitutets arbete med det dricksvattenburna utbrottet i Östersund 2010–2011"). 

Swedish Institute for Communicable Disease Control, Solna. 

http://www.smittskyddsinstitutet.se/upload/Publikationer/Cryptosporidium-i-Ostersund-2011-15-4.pdf 

Sokolova, E., Åström, J., Pettersson, T.J.R., Bergstedt, O. & Hermansson, M. (2012a). Decay of Bacteroidales 

genetic markers in relation to traditional fecal indicators for water quality modeling of drinking water 

sources. Environ. Sci. Technol. 46(2), 892-900. 

Sokolova, E., Åström, J., Pettersson, T.J.R., Bergstedt, O. & Hermansson, M. (2012b). Estimation of pathogen 

concentrations in a drinking water source using hydrodynamic modelling and microbial source tracking. J. 

Water Health, in press. 


Session 3: Dricksvattenkvalitet 

Övervakning av förändringar av vattenkvaliteten 

i distributionssystem 100 

Nya metoder för on-line-detektering av 

mikrobiologisk dricksvattenkvalitet 105 

Effekten av förbättrad vattenrening på mikro- 

organismer i Oslos distributionssystem för vatten 115 

Mixed bed-filtrering i ytvattenrening 123 

Dricksvattenkriser berör oss alla! 131 

Ökad kunskap om snabbsandfilter 133 

Förändringar i sammansättningen av organiskt 

kol under dricksvattenproduktion 138 

Analys av bakteriestammar i biofilmer i 

dricksvattennät i södra Sverige 142 

Avancerad analys av hålrumsmembran i 

pilotförsök med UF/koagulering 146 

Praktiska erfarenheter av avhärdning i 

fluidiserad bädd 151 

99

Monitoring of water quality changes in a distribution system 

Ikonen Jenni*, Juntunen Petri**, and Ilkka T. Miettinen 

* National Institute for Health and Welfare, Department of Environmental Health, Water and Health Unit, 

P.O. Box 95, FI-70701 Kuopio, Finland 

** University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland, Department of Environmental 

Sciences, Process Informatics Kuopio Finland 

Abstract. In Europe, drinking water quality monitoring is based on the verification of the water quality 

in the consumers` tap. This is achieved by sampling and analyzing tap water samples. No continuous 

monitoring of water quality and detection of unwanted agents in distribution system is included in routine 

water quality verification procedures carried out by drinking water suppliers. This procedure leaves multiple 

scenarios enabling water quality deterioration between the water purification plant and the tap (Dufour et 

al., 2003) and it gives a need for on-line monitoring. The main goal of the study was to determine how online 

monitoring can be used in drinking water (microbial, chemical) quality monitoring in a full-scale 

distribution network. 

The distribution network of the city of Kuopio was selected as a target site. Drinking water quality 

was monitored in five different sampling points and with two YSI multiparameter on-line sondes for 9month 

monitoring period. Three of these sampling points were situated in wells and two at the pumping 

stations in the network. Water samples were taken weekly from the network to validate the on-line data. In 

Kuopio, drinking water is produced in two different artificially recharging ground water works: Hietasalo and 

Jänneniemi. During the monitoring session it was seen that water sources could be separated in on-line 

monitoring according to their different electron conductivity (EC) values. This was specially shown during 

weekends when the portion of drinking water from Jänneniemi was larger than on the other week days. 

Changes in EC could thus be used as a tracer enabling the follow-up of water movements in the drinking 

water network and the detection of changes in production processes. 

As a reference data to on-line measurements (temperature, pH, EC and turbidity) both 

microbiological (plate counts, total counts) and chemical (iron, manganese and aluminium) analyses were 

carried out. Also physico-chemical parameters (T, pH, EC, residual chlorine, O2, NTU, particles/ml, abs 

254nm and abs 420nm) were measured. We also wanted to explore the connection between on-line 

measurements and the microbial quality of drinking water. It was found that 10/29 of these peaks Fe/Mn 

events were related to elevated bacterial counts (HPC) in water. 

Challenges of on-line water quality monitoring 

At the moment drinking water quality control is focused on the water quality in the consumers tap and 

the quality of drinking water in the network is not under main scope. In Finland, the quality of drinking 

water is regularly controlled by water plant itself and by municipal authorities, who take water samples 

from the produced water. However, sampling and analysis of a sample may also effect on the final result 

that indicates the quality of water. Methods based on cultivation will take time and some methods such as 

PCR will depend on the concentration of contaminants in water. Also time, when the sample has been 

taken can effect on a final result. This leads to a situation where the quality of drinking water may fully 

comply with the quality requirements and guidelines indicating acceptable quality of water. However, 

possible (especially acute) contamination may not be discovered. Thus, the need for quicker observation 

methods prevails. One solution for improved water safety could be to apply on-line monitoring 

technology to observe water quality changes in drinking water network. 

On-line monitoring of water quality in the drinking water network gives many benefits. One is the fact 

that an on-line sensor in a network can monitor large amount (majority-all) of water, while routine water 

100 Session 3: Dricksvattenkvalitet

sampling covers only a small fraction of all distributed drinking water. On-line monitoring of the drinking 

water quality enables (at least in principle) constant real-time detection about the quality of distributed 

drinking water. 

However, monitoring of drinking water quality in the network is challenging. Main issues to be 

considered when planning the on-line monitoring is the determination of the measuring points in the 

network, what parameters to be measured, what is the monitoring frequency and how many sensors are 

required. From technical point of view also power supply (e.g. battery) and data transfer systems must be 

taken care of. In this sense, existing monitoring wells and pumping stations can be utilized as locations 

for sensors. 

Utilizing multiple bulk parameters in on-line monitoring is gaining ground and it has been stated that 

inferential surrogate monitoring can be used as early-warning systems, so that no specific compound of 

interest is used (Kroll 2010). In Finland on-line monitoring concerns generally measurement of pH, 

temperature, electric conductivity and free residual chlorine of the water distributed from water works. In 

the drinking water distribution network monitoring other parameters besides hydraulic (water 

flow/pressure) is quite rare (national inquiry to Finnish water works, Vesikko project). 

The major challenge dealing with on-line monitoring of drinking water quality concerns the quantity 

and quality of data. Typical features of on-line data quality include roaming of baseline, unexpected 

sudden steps, outlayer signals and background noise. The unstable (uncoherent) data requires processing. 

False alarms can be minimized by using sensor management and data analyzing. It has been stated that 

attention/concentration should be pointed into a magnitude, shape and duration of the peaks in data. 

Longer and bigger peak will indicate change in larger water volume indicating significant change in water 

quality (Kroll 2010). 

Monitoring experiences 

The main goal of this study was to determine how on-line monitoring can be used in drinking water 

(microbial, chemical) quality monitoring in a real drinking water network. The distribution network of the 

city of Kuopio (Kuopio Water) was selected as target site for the study. There was five different 

monitoring points in the network. Two YSI multiparameter sondes (YSI 600XLM-V2-M and YSI 6920- 

V2-M) were applied for water quality monitoring which lasted for 9 months. Three of these monitoring 

points were situated in monitoring wells and two at the pumping stations of the network used by Kuopio 

Water. Besides the on-line monitoring laboratory analyses from water samples of the network were used 

as validation material. The water samples were taken three times per every week. Every month included 

an extensive monitoring week which included sampling on every working day. 

YSI sondes enable on-line monitoring of temperature, pH, electric conductivity and turbidity. An 

important feature of the Kuopio city is the fact that drinking water is produced in two different artificially 

recharging ground water works: Hietasalo and Jänneniemi. During the monitoring session it was seen that 

water sources could be separated in on-line monitoring according to their different electron conductivity 

(EC) values: Hietasalo had 50µS/cm lower EC than in water abstracted at Jänneniemi. This was specially 

shown during weekends when the portion of drinking water originating from Jänneniemi is larger than on 

other week days. This EC peak could be used as a tracer enabling to monitore water movement in the 

distribution system and to detect changes in production process. The detected EC peaks had a different 

shape in different monitoring points. The peak was clearer at the monitoring point A which is placed 

close to the water plant. (Figs. 1 and 2). 

With on-line monitoring it was observed that electric conductivity was good parameter to express 

water quality e.g. from which raw water source was used. The most challenging parameters to be 

monitored were turbidity and pH, which both demanded more frequent sensor maintenance and 

calibration than the measurements of electric conductivity or temperature. Turbidity data was challenged 

by frequent outlayers. Thus, the turbidity data required constant processing. It can be concluded that data 

analyzing is essential part of not only turbidity data but over-all data obtained through on-line monitoring 

systems. 

Session 3: Dricksvattenkvalitet 101

Figure 1 Figure 1. On-line monitoring period of EC at the monitoring point A at 9.5. – 22.9.2011 (no EC 

peaks were detected at 10 – 12.6.2011 because of maintenance at water plant) 

Figure 2. On-line monitoring data of EC at the monitoring point E at 9.5 – 26.6.2011. (no EC peaks 

were detected at 10 – 12.6.2011 because of maintenance at water plant) 

Laboratory analyses 

As reference data to on-line monitoring both microbiological (HPC on R2A, TMC with DAPIstaining) 

and chemical (iron, manganese and aluminum) analyses were carried out. Also physicochemical 

parameters like temperature, pH, EC, residual chlorine, O2, NTU, particles/ml, abs 254nm and 

abs 420nm were measured to obtain reference data which can be compared with on-line monitoring data. 

During the monitoring period iron exceeded 29 times value of 0,2 mg/l and manganese 11 times value 

0,05 mg/l (Anon 2000). The average laboratory results of the monitoring period are present at the Table 1. 

The general assumption was that turbidity peaks would be related loose deposits which could carry 

microbes. The study showed that 10 out of 29 peak value cases of high Fe/Mn were related with 

simultaneously elevated bacterial counts (HPC) in water. 


Table 1a. Average values of water quality parameters at five monitoring points of Kuopio DW 

network. 

T EC Residual Turbidity Particles Abs 

(C) (µS/cm) Cl (NTU (>,5µm/ml)* 254nm 

A 8,5 242 0,27 0,03 1761 0,228 

*particles measured as 1/10 dilution in UP water 

Table 1b. Continuation : Averages of water quality parameters at five monitoring points of Kuopio DW 

network 

Conclusions 

B 7,2 246 0,19 0,23 4286 0,237 

C 7,5 247 0,16 0,09 3555 0,232 

D 8,2 252 0,09 0,41 4696 0,258 

E 8,4 248 0,13 0,16 2585 0,231 

Iron 

(mg/l) 

Manganes 

e 

(mg/l) 

Aluminium 

(mg/l) 

HPC 

(CFU/ml) 

TMC 

(cells/ 

ml) 

A 0,04 0,026 0,032 20 41 000 

B 0,08 0,044 0,031 300 42 000 

C 0,07 0,080 0,032 500 60 000 

D 0,18 0,032 0,023 2700 41 000 

E 0,09 0,027 0,034 400 47 000 

Changes in water quality can be detected by on-line monitoring devices. This provides in principal a 

useful tool for verification of drinking water quality. 

Basic parameters measured as on-line like electron conductivity or temperature may provide useful 

information about water quality in drinking water network. In Kuopio case electron conductivity could be 

used as a tracer indicating water flow patterns in the distribution networks. In addition to, several peak 

events of turbidity were detected. Some of those peak events could be associated with high Fe/Mn (loose 

deposits) . 

The study underlined the technical challenges related with on-line monitoring. Some of the sensors 

(especially pH and turbidity) require intensive maintenance and calibration. 

On-line monitoring of microbial drinking water quality is extremely challenging. The study confirmed 

the concept that the present on-line sensors enable detection of physico-chemical quality changes, but do 

not make possible direct detection of microbes, not even changes in total microbial counts which are 

much higher than HPC. High expectations was put in the study on indirect detection of microbes. 

However, it could be proven in this study that not even the on-line monitoring of turbidity could predict 

changes in microbial counts in drinking water. Thus, in terms of microbial drinking water quality 

traditional laboratory analyses of microbes prevail over the on-line monitoring. 


References 

Anon. 2000. Degree of the Ministry of the Social Affairs and Health 461/2000 relating to the quality and monitoring 

of water intended for human consumption. 2000. Helsinki (in Finnish). 

http://www.finlex.fi/fi/laki/alkup/2008/20080177. 

Dufour, A., Snozzi, M., Koster, W., Bartmram, J., Ronchi, E., Fewtrell, L. Assessing Bacterial Safety of Drinking 

Water. (2003) WHO Drinking Water Quality Series. 295s . London SW1H 0QS, UK. 

Kroll D., (2010) Is it real or isn`t it? Addressing early warning systems alarms. Water contamination emergencies: 

Monitoring, understanding, acting. Edited by K. Clive Thompson and Ulrich Borchers STM (2000). 

Acknowledgements 

This work was a part of a national Sävel project (968/31/08), which is funded by the Finnish Funding Agency for 

Technology and Innovation (TEKES). We acknowledge the help obtained from Kuopio Water, University of Eastern 

Finland and the personnel of National Institute for Health and Welfare in Kuopio. 


New methods for on-line detection of coliforme bacteria in 

drinking water 

Niels Erik Bjergaarde* and Eva Hansson**, 

*Københavns Energi A/S, e-mail: nebj@ke.dk **Roskilde Forsyning A/S, e-mail:evah@rosforsyning.dk 

Abstract. During our work at the water supplies, we have obtained practical experiences with a number of 

fast detection methods for microbial quality. In this work we focus on fast methods for detection of 

coliforme bacteria and to a lesser extend Escherichia coli (E-coli). Our experiences include the following 

methods: The process analyzers mBonline Coliguard® and Colifast ALARM® and the operational tools 

“Integrated Sample Unit” where the laboratory method Colilert-18®/Quanti-Tray® is used to quantify the 

coliforme and E-coli bacteria. 

The methods will be described with regards to detection limits, response time, operational qualities, and 

limitations to operation. The process analyser Colifast ALARM® has been on the market for a couple of 

years and is used as a part of daily operation control at Københavns Energi, whereas Coliguard® is new 

on the Danish market. The three water supply companies of Copenhagen, Roskilde, and 

Gentofte/Gladsaxe, and the company Amphi-Bac have in collaboration tested the analyzer directly in our 

full-scale production facilities with regards to detection limits, response time, operational qualities, and 

limitations to operation. 


Introduction 

In Denmark, groundwater covers almost 100% of our need for drinking water. It is a political decision 

that the drinking water should be treated as simple as possible before it reaches the taps of the consumers. 

Typically, treatment consists of aeration and filtration (removal of iron and manganese) at the water 

works before the water is pumped into the distribution net to the consumers. 

A barrier such as chlorination of drinking water is not common practice. Thus, in order to insure healthy 

drinking water with good bacterial and physical/chemical quality it is critical to have fast methods, which 

can monitor drinking water quality during production and distribution. Water works, researchers, and 

consultants are constantly challenging the limits for detection and delivery of results developing new 

methods for rapid microbial quality control. 

During our work at the water supplies of Copenhagen, Gentofte/Gladsaxe, and Roskilde areas, we have 

obtained practical experiences with a number of fast detection methods for microbial quality. The purpose 

of this presentation is to share our experiences with on-line methods installed directly at outlets from our 

waterworks. The focus is on coliforme bacteria and to a lesser extent Escherichia coli (E-coli). Our 

experiences include the following process analyzers: Coliguard® and Colifast®, and the operational 

tools “Integrated Sample Unit”, where the laboratory method Colilert 18®/Quanti-Tray® is used to 

quantify the coliforme and E-coli bacteria. All techniques have the potential to establish an important part 

of continuous operation and control of microbial quality in drinking water production. 

These methods are developed to monitor the sanitary quality of water upon detection of indicator bacteria 

such as coliforme bacteria and E-coli as fast as possible. As mentioned the Danish water works are 

privileged with a relatively good microbial raw water quality. Without barriers as chlorination etc. water 

of good sanitary quality is supplied. In normal situations the detected level of coliforme bacteria is low 

from the water works to the consumer. Higher levels are used in the operation and control procedures as a 

warning signal for leakage, accidental pollutions, failure in treatment processes etc. In these situations we 

are challenged in time and the need for faster methods is obvious. 

Methods 

“Integrated Sample Unit” 

In the Danish water supply sector the standard methods ISO EN 9308-1:2001 and Colilert®/Quanti- 

Tray® are used for detection of coliforms and E-coli. Grab sampling with a sample size of 100 ml. is the 

common procedure. The use of large sample volume and longer sampling periods improve the sensitivity 

in the detection of coliforms in our systems. 

A sampling unit with the possibility to take out larger samples and use longer sampling periods has been 

integrated in the operation and control at the waterworks cooperating in this project. This sampling unit is 

named “Integrated Sample Unit” 

Figure 1: “Integrated Sample Unit” Figure 2: Extraction of coliforme bacteria from filter paper 


In the sampling unit the sample is filtered through a sterile filter unit. The coliforms are caught on the 

filter surface. After a determined filtration time and -volume the filter-unit is removed and transported to 

the laboratory. The coliforms are extracted from the filter and the number of coliforms is analyzed using 

the Colilert-18®/Quanti-Tray® method. By filtration of 100 litres of water sample during 24 hours the 

detection limit of coliforms and E-coli is improved 1000 times compared to normal procedure with grab 

sampling of 100 ml. This sampling unit was installed at the test points in order to compare the results of 

the Coliguard® and the Colifast® with the Colilert® method. 

Colilert-18®/Quanti-Tray® 

The enzyme substrate test from US Company IDEXX was used for simultaneous detection of coliforms 

and E-coli numbers in the spiked water samples in our tests. Also in connection with the use of the 

sampling unit in the operational tests of the process analyzer. 

Figure 3: Quanti Tray® wells from the Colilert® MPN method 

Colifast process analyzer ALARM® 

The Colifast ALARM® is developed and produced by the Norwegian Company Colifast AB. The 

company has been working with automation of methods for bacteria detection and measurement in food 

and water for the past 20 years. 

The Colifast ALARM® is a stand-alone at-line early warning system developed for detecting either one 

of the three following microbial parameters: Total coliforms, faecal coliforms, or E-coli in 100 ml water 

samples. 

Detection of target bacteria is based on selective growth in Colifast® medium and the hydrolysis of 

fluorogenic substrates by specific bacterial enzymes, which ensure accurate results, detecting only 

cultivatable bacteria of the target group. 

The analyzing time for the sample is 15 hours. After this time a final result for the sample is reported. If 

the result is positive coliforme bacteria is present at a level above 1 coliform/100 ml, and below 1 

coliforme/ 100 ml if the result is negative. The first measurement on the incubated sample is performed 

after 6 hours (early warning for high levels of coliforms) and the system continues to measure every hour 

until the final 15 hours. 

The result is then reported by following options decided by the end user: SMS, LAN and PLC interfacing 

and audio-visual alarms at the local position of the actual analyzer-system. Københavns Energi decided to 

buy the system after a trial project in 2010. 

It has been operating continuously with good and stable results since June 2010, at a control point at the 

water storage facility for Copenhagen, Tinghøj. It runs every day all year around. A major advantage 

developed is the possibility to do testing at night, where no manual sampling and following laboratory 

analysis can be provided under normal conditions. By the use of the system, incidents with abnormal high 

level of coliforms have been detected with following trouble shooting in our systems to find the reason. 


Figure 4 and 5: The Colifast ALARM installation at Københavns Energi, Tinghøj water storage facility. 

“Remote Desktop” operation. Example of an unusual situation. Detection of high level of coliforms 

mBonline Coliguard® process analyzer 

The three water supply companies of Copenhagen, Gentofte/Gladsaxe, and Roskilde, have in 

collaboration tested Coliguard® from the Austrian company MB-Online GmbH founded in 2008, which 

is a new on-line method for monitoring coliforme and E-coli bacteria. The Coliguard® method can 

deliver a result in three hours, which to the writers‟ knowledge is the lowest response time to date. 

Coliguard is already used at drinking water supplies in a number of countries in Europe, however; so far it 

is mostly used on drinking water resources originating from surface water, which contains much higher 

concentrations of bacteria than ground water. Thus, in order for Danish water works to be interested in 

this new method a low detection limit is a key issue. As a part of the test of MB-online Coliguard®, 

results have been compared with traditional microbial methods, which were used in parallel for 

comparison. 

In order to make the study more applicable to everyday operation at the water works, the apparatus was 

tested directly in our full-scale production and distribution systems. So far, it has not been possible to find 

automated or manual methods, which can deliver a reliable result in such a short time span. We were 

therefore eager to see whether this tool was able to fulfil the promised specifications and our expectations. 


The full automatic system can either detect low levels of coliforms or E-coli by measuring their 

biochemical metabolic rate during fluorescencoptical measurements. 

Figure 6: The internal operation side of the mB-Online Coliguard® analyzer 

The enzymatic activity of coliforms is detected by measuring the concentration of β-galactosidase, 

whereas E. coli are determined by measuring the concentration of β-glucuronidase, an enzyme, which is a 

selective marker for E-coli. Results are typically delivered directly to our SCADA-systems in three hours, 

which is the major advantage compared to the standard control methods. 

The sample volume can vary in a range up to 3000 ml; in our test it was preset to 2000 ml. The sample is 

filtered through a ceramic filter, where after the filter sample is mixed with either coliforme- or E-colireagent. 

After each measurement the ceramic filter and reaction chamber is cleaned with a cleaning 

solution. 

The mboClient is a JAVA based application that can be installed on any PC. The user face is user 

friendly, besides the presentation of the measuring results in a clearly arranged diagram, instrument 

parameters can be displayed and adjusted. The module „Timetable “allows the setup of a sophisticated 

schedule when measurements are to be performed, the system status informs about the remaining 

quantities of consumables. An integrated export module permits the export of data e.g. into an excel 

spreadsheet for further processing. 

The Coliguard apparatus was installed and ran continually for six months at Critical Control Points at two 

water works in Hørsholm and Roskilde, and at the Tinghøj storage facility. 

Figure 7: Operational test of the Coliguard analyzer 

The background enzyme level of β-galactosidase was stable at each location, but varied with locations. At 

Tinghøj the level of β-galactosidase correspond to 1,4 coliforms/100 ml with the conversion factor being 

used, but no β-glucuronidase background was detected. At Haraldsborg and Sjælsø the levels of β- 


galactosidase correspond to 1,6/ 100 ml and 2,0/100 ml neither at these two sites any β-glucuronidase 

background was measured. 

Actvity [pMol/minute] 

3 

2,5 

2 

1,5 

1 

0,5 

0 

Tinghøj Haralds borg S jæ ls ø 

18.12.11 27.01.12 07.03.12 16.04.12 

Figure 8: Background enzyme activity levels at the three water facilities during the test period. 

Simultaneously Colilert analysis didn’t show presence of coliforme bacteria or E. coli. 

The water was simultaneously been analyzed using the “Integrated Sample Unit” followed by a Colilert® 

measurement on the filter wash off. The Colilert analysis did not show the presence of either coliforms or 

E-coli at any of the three sites. The reason for the variation of background β-galactosidase level may be 

due to the presence of other microorganisms such as protozoa and other bacteria. 

Spiking experiments 

Because no true water contamination occurred through the testing period, three types of spike tests were 

carried out. The first spike test was carried out at Tinghøj. This was done by spiking 20 L of drinking 

water from the Tinghøj storage facility, with freeze dried coliforme bacteria with a certified number of 

bacteria. In order to verify the concentration two water samples were simultaneously analysed by the 

Colilert method. The results of the Colilert method were 6 coliforms/ 100 ml.The first spiking experiment 

showed clearly a difference between background level and the „contaminated‟ level, which was very 

promising. 


4 

3,5 

3 

2,5 

2 

1,5 

1 

0,5 

1. Spiking experiment 

Water spiked with 6 

coliforme cfu/100 ml 

Background enzyme level 

0 

26-01-12 28-01-12 30-01-12 01-02-12 03-02-12 

Figure 9: First spiking experiment was carried out using freeze dried coliforme bacteria. Colilert analysis 

showed a concentration of coliforme bacteria at 6 cfu/ 100 ml. 


In the second spike test, we were interested in testing the detection level of the Coliguard apparatus. In 

this test water from the Tinghøj sub container number 6 was analysed. Sub container number 6, which is 

closed down for repair, contained water contaminated with coliforme bacteria at concentrations of 1-2 

coliforms/ 100 ml. 20 L was twice analysed by the Coliguard® apparatus. At the beginning of each test, 

water samples were analysed by the Colilert method. 

The result of the first analysis (2.1) of Tinghøj-water from sub container number 6 showed an increase in 

enzyme level to a concentration 2 times above background level. At the second analysis (2.2) the enzyme 

level didn‟t increase above background level. We cannot explain the reason for this difference. In order to 

assure that it isn‟t a malfunction of the apparatus the Coliguard instrument is currently in for testing. 


3,5 

3 

2,5 

2 

1,5 

1 

0,5 

2.1 Spiking experiment 

Backgr.enzyme level 

(BEL) 

BEL 

Water spiked with 1-2 


0 

22-03-12 24-03-12 26-03-12 28-03-12 30-03-12 01-04-12 


3,5 

3 

2,5 

2 

1,5 

1 

0,5 

2.2 Spiking experiment 

0 

04-04-12 05-04-12 06-04-12 

Figure 10 Second spiking experiment, which consists of two repetitions. Simultaneously Colilert analysis 

showed the presence of 1-2 coliforme bacteria. BEL: background enzyme level 

In the third experiment we wanted to examine whether there was a linear dependence in enzyme activity 

and coliforme as well as E. coli concentration, furthermore, we wanted to test the detection limits once 

again. An spike sample of 20 litres with “a target concentration” of around 20-30 coliformes/100 ml was 

made by adding fresh wastewater to drinking water taken from the tap. (Dilution factor around 

1/40000).This sample was analyzed for typical water parameters and microbial quality parameters. 

During a period of three days a 20 l solution of strongly dissolved wastewater (1/40000) was stepwise 

added drinking water resulting in lower and lower concentrations of coliforms and E-coli. The solution 

was monitored during the three days, each day the Coliguard® apparatus performed two analyses for 

coliforme bacteria followed by two analyses for E-coli. At the end of each day a known volume of 

drinking water was added to the left over volume of solution resulting in a dissolution series of 

approximately 1, 5/6, and 1/4. Thereby, approaching the detection limits of the Coliguard® apparatus. 

This approach would also allow us to examine whether the enzyme activity of the bacteria would follow 

the concentration levels detected by the Colilert method. 

The sample of waste water dissolved into 20 L of drinking water resulted in an average concentration of 

coliforms at 25/ 100 ml and E-coli at 7/ 100 ml according to the corresponding Colilert analysis. Due to 

the-stability of the bacteria it was necessary to decrease the addition of drinking water on day 2 and 3 to 

the absolute minimum in order to ensure enough bacteria to measure. In each sample- round two samples 

were taken both of which were analysed twice. The average result of each sample is shown in the table 

below. 

Table 1 Third spiking experiment was carried out over a period of three days. Simultaneously Colilert 

analysis showed the presence of coliforme bacteria and E. coli. 

BEL 

Water spiked with 1-2 


Session 3: Dricksvattenkvalitet 111 

BEL

Colilert 

(coliforms/100 ml) 

Double sampling 

Colilert 

(E-coli/100 ml) 

Double 

sampling 

Background

Figure 12: E-Coli. Third spiking experiment was carried out over a period of three days. Simultaneously 

Colilert analysis showed the presence of coliforme bacteria according to the table above. BEL: background 

enzyme level 

It was not possible in the third experiment to distinguish between the background level and a low level 

contamination with up to 34 coliforms/ 100 ml and 8 E-coli/ 100 ml. This result is puzzling because it 

seemed possible to distinguish levels at 6 and 1-2 coliforme bacteria in the first two spiking experiments. 

Furthermore, AmphiBac reports to have measured levels of 1-10 coliforme bacteria in own tests. 

The Coliguard apparatus has been sent to a thorough testing in order to check it for malfunctions. 

However, if the Coliguard isn‟t capable of distinguishing between low levels of coliforme bacteria it is 

very unfortunate in a Danish context, because legal limits are low. 

Conclusion 

Several incidents of contamination of drinking water with Coliforme bacteria makes it clear that there is a 

need for rapid methods for detection of unwanted bacteria in our drinking water.With regards to 

coliforme and E. coli bacteria we have obtained practical experiences with three on-line methods: Colilert 

18, Colifast, and Coliguard. 

Colilert 18 and Colifast are based on selective growth whereas Coliguard is based on measurement of 

enzyme activity. Selective growth techniques require a much longer time span for result delivery. In both 

cases it takes 18 hours to obtain a result, however, Colifast provides the option for an early warning after 

6 hours in case of a major contamination. Because Coliguard is based on measuring the enzyme activity it 

is possible to deliver a result in three hours. On the downside enzyme activity based techniques aren‟t as 

precise as selective growth techniques, which again only focus on a fraction of bacteria that is growth 

able. 

Colilert 18 and Colifast are used in the daily operation, and deliver steady and reliable results, and are 

easy to operate and maintain. Coliguard has a more advanced user interface than Colilert 18 and Colifast, 

which provide the user with several options for set-up. 

The test for whether Coliguard is able to reliable results in the low contamination level range is not 

conclusive. The first half of the test showed positive results whereas the last half showed negative results. 

In order to rule out instrument malfunctions the instrument is in for a thorough inspection which will be 

done before the conference presentation. 


References 

T.Garcia-Armisen, P.Lebaron and P. Servais. (2005). Β-D-glucuronidase activity assay to assess viable Escheria coli 

abundance in freshwaters. Letters in Applied Microbiologi, 40, 278–282. 

I.Tryland, I.D Samset, L. Hermansen, J.D Berg and H. Rydberg. (2001). Early warning of faecal contamination of 

water: a dual mode, automated system for high- (< 1 hour) and low-levels (6-11 hours). Water Science and 

Technology, Vol 43 No 12, 217–220. 

I.Tryland, S. Surman and J.D. Berg (2002). Monitoring faecal contamination of the Thames estuary using a 

semiautomated early warning system. Water Science and Technology, Vol 46 No 3, 25-31. 

Niemela, SI, Lee, JV & Fricker, CR (2003) A comparison of the International Standards Organisation reference 

method for the detection of coliforms and Escherichia coli in water with a defined substrate procedure. Journal. 

of Applied Microbiology, 95, 1285 - 1292. 

J.S Hall, J.G Szabo, S. Panguluri, G. Meiners (2009) Distribution System Water Quality Monitoring: Sensor 

Technology Evaluation Methodology and Results. U.S. Environmental Protection Agency,EPA 600/R-09/076 , 

October 2009 

Storey MV, van der Gaag B, Burns BP (2011), Advances in on-line drinking water quality monitoring and early 

warning systems.Water Reseach, 45 (2), 741-747 

EN ISO 9308-1 (2001) Water quality – Detection and enumeration of Escherichia coli and coliform bacteria – Part 1: 

membrane filtration method. DS/EN ISO 9308-1 


Effekten av forbedret vannbehandling i Oslo på mikrobiologisk 

vannkvalitet i distribusjonssystemet for drikkevann 

Lars J. Hem * , Vidar Lund ** , Mary Anderson-Glenna *** , Ida Skaar **** 

* SINTEF, Oslo, Norge, lars.hem@sintef.no 

** Folkehelseinstituttet, Oslo, Norge, Vidar.Lund@fhi.no 

*** Folkehelseinstituttet, Oslo, Norge, mjanderson19@yahoo.co.uk 

**** Veterinærinstituttet, Oslo, Norge, ida.skaar@vetinst.no 

Abstract. 

In 2008 the new Oset water treatment plant in Oslo, serving almost 0.5 million people, was set in 

operation. While the old plant mainly consisted of chlorination, the new plant include NOM removal, UVdisinfection 

and corrosion control. 

The presence of moulds as well as the possible presence of opportunistic pathogenic bacteria in the 

distribution system has been a concern for the waterworks in Oslo for some time. As a result they wanted 

to know the impact of the extended treatment on the microbial community in the system. The results 

presented here are the main outcome of measurements performed to clarify this effect. 

ATP was measured according to a bioluminescence method. 

Mould was enumerated according to a Norwegian standard method (NS 4716) by filtering, incubated for 

up to two weeks. 

DNA was extracted from water samples concentrated by filtration. Bacterial community diversity was 

examined using two methods targeting the 16s rRNA gene. Cloning and sequencing was used to identify 

bacterial species within the samples and a fingerprinting technique, Terminal Restriction Fragment Length 

Polymorphism (TRFLP), was used to examine the bacterial community structure and variation between the 

plant outlet and one sampling point in the distribution system 

The ATP in the water in the distribution system decreased with 75-90 % as a result of the new 

treatment. The mould content decreased from 10-20 colonies/100 mL to zero after the start-up of the new 

plant. The effect of the treatment was considerable on the quantitative micro-biological content both in the 

water delivered from the plant and in the distribution system. 

As opposed to previous findings the mould content in the drinking water from the old plant was quite 

stable through the distribution system, indicating that the source was the raw water rather than growth in 

the pipes. 

Bacteria recovered from the test water belonged to 10 common freshwater bacterial Phyla of which 

Proteobacteria and Planctomycetes were the most abundant. Bacterial sequences closely related to the 

opportunistic pathogens Sphingomonas mucosissima, Janthinobacterium lividum, Delftia acidovorans, and 

Aquabacterium sp. were detected. The Genus Legionella was observed in all samples with clones being 

related mostly at the genus level. 

The diversity of the bacterial communities decreased by 22- 42% after the new water treatment facility 

came into operation, the highest decrease at the plant outlet. 

A change in the water treatment mainly applied in order to remove colour from NOM and to inactivate 

parasites also had a pronounced effect on both the quantitative and qualitative microbiology in the 

distribution system, with reductions in bacterial diversity, moulds and ATP. 

Sammendrag 

Det ble gjennomført kvantitative og kvalitative mikrobiologiske målinger på den delen av Oslos 

ledningsnett som forsynes fra Oset vannbehandlingsanlegg. Målingene ble gjennomført med det formål å 

klarlegge hvilken effekt det nye vannbehandlingsanlegget har på den kvantitative og kvalitative 

sammensetningen av mikroorganismene i drikkevannet. Effekten av den nye vannbehandlingen på den 

kvantitative mengden mikroorganismer i drikkevannet var både rask og tydelig. 1-2 uker etter at ny 

behandling var satt i drift sank mengden muggsopp til null, mens mengden ATP sank med 75-90 % 

avhengig av prøvepunktet. Analyseresultatene for muggsopp tilsier at med den gamle vannbehandlingen 

var råvannet en viktig kilde til muggsopp i drikkevannet på nettet, og at disse mikroorganismene holdes 

tilbake og/eller inaktiveres i det nye vannbehandlings-anlegget. Den kvalitative endringen for bakterier 

besto dels i at mangfoldet i bakteriesammensetningen sank etter at det nye vannbehandlingsanlegget ble 


tatt i drift og dels i at enkelte opportunistiske bakterier som ble påvist i ledningsnettet med gammel 

vannbehandling ikke ble påvist med ny vannbehandling. 

Oset vannbehandlingsanlegg 

Dagens råvannskvalitet har et fargetall på ca. 25-30 mg Pt/l, turbiditet < 1 FNU, pH ca. 6,5, alkalitet 

ca. 0,1 mekv/l og kalsiumkonsentrasjon ca. 3 mg Ca/l. Det er et betydelig innhold av koliforme bakterier 

og E.coli hver høst og sporadisk påvisning av parasittene Giardia og Cryptosporidium. Forekomstene av 

ulike typer virus er ikke kartlagt. 

Det nye Oset vannbehandlingsanlegg er bygget for å fjerne humus som gir vannet en gulbrun farge, å 

gi vannet en behandling som reduserer korrosiviteten overfor sement- og metallbaserte materialer og for å 

etablere to hygieniske barrierer mot bakterier, virus og parasitter. 

Oset vannbehandlingsanlegg omfatter vannbehandling, slambehandling samt behandling av 

rejektvannet før dette slippes til avløpsnettet. Flytskjema for hele anlegget er vist i figur 1. 

Figur 1 Flytskjema for Oset vannbehandlingsanlegg 

I vannbehandlingsdelen av anlegget tilsettes vannet karbondioksid, kalk som tilsettes i form av mettet 

kalkvann, koagulant som p.t. er den aluminiumbaserte PAX 18, mikrosand og polymer. Etter flokkulering 

ledes vann med fnokker inn i Actifloenheten som er en lamellsedimenteringstank. Vannet som går ut av 

sedimenteringstanken har en turbiditet på i underkant av 1 FNU. Etter lamellsedimentering ledes vannet 

til et to-media sandfilter for fjerning av resterende partikler, og etter filteret har vannet en turbiditet på ca. 

0,1 FNU. Dersom turbiditeten overstiger 0,2 FNU ut av et filter stenger filteret automatisk og filteret 


plasseres i kø for tilbakespyling. Den delen av vannbehandlingsanlegget som utgjøres av koagulering, 

sedimentering og filtrering utgjør anleggets første hygieniske barriere. 

Filtrert vann går til UV-desinfeksjonstrinnet som utgjør anleggets andre hygieniske barriere. Det er tre 

lavtrykks UV-aggregater i både anlegg syd og anlegg nord, og anlegget er designet slik at ett aggregat til 

en hver tid er i stand-by. 

Etter UV-desinfeksjonen er det opplegg for dosering av natriumhypokloritt. Dette er primært tiltenkt 

en situasjon der forutgående behandling ikke klarer å øke vannets UV-transmisjon tilstrekkelig slik at 

UV-dosen blir for lav. I en slik situasjon skal vannet kloreres i tillegg. For å sikre at anlegget til en hver 

tid er operativt doseres små mengder natriumhypokloritt, typisk 0,1 mg Cl2/l, også når UV-anlegget 

fungerer tilfredsstillende. 

Til slutt justeres pH til ca. 8,0 med mettet kalkvann. Anlegget er designet for å kunne dosere kalk og 

karbondioksid til innholdet av kalsium blir 28 mg Ca/l og alkaliteten 1,2 mekv/l, men VAVs mål for 

rentvannskvaliteten er 17 mg Ca/l og 0,7 mekv/l. 

Slam fra sedimenteringen fortykkes og avvannes. 

Vannbehandlingsanlegget er designet for en vannproduksjon på 390.000 m 3 /d med et fargetall i 

råvannet på inntil 45 mg Pt/l. 

Innkjøringen av Nye Oset vannbehandlingsanlegg (vba) startet tidlig i 2008 og ble offisielt avsluttet i 

april 2009. I løpet av denne perioden ble det produsert vann vekselvis i gamle og nye Oset vba. VAV 

ønsket å kartlegge mikrobiologisk vekst på ledningsnettet med gamle og nye Oset vba for å få et grunnlag 

for å vurdere effektene av den nye vannbehandlingen på slik vekst. Vurderingene av mikrobiologiske 

forhold på ledningsnettet ble basert på vannprøver i stedet for biofilmvekst direkte fordi vannkvaliteten i 

innkjøringsperioden varierte betydelig. Dette skyldtes at det i perioder kun ble produsert vann med det 

gamle anlegget, i perioder kun med det nye og i perioder med en blanding av det gamle og det nye 

anlegget. 

Det tidligere vannbehandlingsanlegget på Oset besto av mikrosiling og klorering og er beholdt som et 

reserveanlegg dersom hele eller deler av det nye anlegget skulle falle ut. Mikrosilene har poreåpning 5 

µm. 

Materialer og metoder 

Prøvetaking 

Det ble tatt prøver av vannet i fire prøvepunkter. Disse er oppgitt under rangert ut fra vannets 

oppholdstid i distribusjonssystemet, beregnet ved å følge vannets vei fra rentvannsbassenget på Oset midt 

på dagen: 

• Rentvann ut fra Oset 

• Furulund basseng der vannet har hatt relativt kort oppholdstid (2,5 timer)i nettet 

• Herslebs gate 5 (H5) (oppholdstid ca. 12,1 timer) 

• Bygdøynesveien som er på en endeledning (oppholdstid ca. 32,5 timer) 

Måleperioden varte fra 01.09.2008 til 28.04.2009. Hver 4. uke ble det tatt prøver i alle 4 prøvepunkt 

som ble analysert med hensyn på ATP og muggsopp, samt at det ble forberedt for analyse av 

bakteriesammensetning ved hjelp av. terminal restriction fragment length polymorphism (TRFLP). Etter 

at analyseresultatene for fargetall, ATP og muggsopp forelå ble det bestemt at bakteriesammensetningen 

skulle bestemmes for prøvene tatt ut fra Oset og i Herslebs gate 5 03.02.2009 da gamle Oset hadde 

produsert alt vannet ut fra Oset i 1,5 måneder og 28.04.2009 da nye Oset hadde produsert alt vannet ut fra 

Oset i drøyt 2 måneder. 


ATP 

Kvantitativ bestemmelse av mengde biomasse ble utført ved analyse av vannets totale innhold av ATP, 

et stoff som produseres av alle levende celler. Dette inkluderer også eventuell ekstracellulær ATP som 

frigis når mikroorganismer dør som følge av desinfeksjon. ATP ble brukt som mål på mengde levende 

biomasse. Målemetoden for ATP er basert på at energien i ATP omdannes til lys med bølgelengde 562 

nm ved hjelp av bioluminescens. Først tilsettes reagenset NRM (nuleotide releasing reagent for microbial 

ATP) som ekstraherer ATP ut av cellene. Dernest tilsettes enzymet luciferin-luciferase som reagerer med 

ATP og omdanner dette med lys som et av produktene etter reaksjonen; 

Luciferin + ATP + O2 → (Luciferase) → Oxyluciferin + AMP + pyrofosfat +CO2 +lys 

Analyse av ATP ble gjennomført ved å måle avgivelse av lys. 

Muggsopp 

For mugganalyse ble det tatt ut tre prøver på hvert prøvepunkt. Noe av prøvemateriale ble drysset 

direkte på overflaten av dichloran glycerol agar 18 % (DG18)-skåler (Oxoid CM 0729) for kvalitative 

analyser. Prøvematerialet ble også løst i sterilt saltvann i forholdet 1:10 i 20 min før de ble fortynnet og 

sådd ut på duplikate skåler av DG18 fra 10 -2 til 10 -6 -fortynning. Skålene ble inkubert ved 25 °C i 7 dager 

plassert opp ned i ventilerte poser. Antall kolonier på skålene ble bestemt og kolonien gruppert mht 

kolonimorfologien. Representative kolonier ble tatt ut sekundært for identifisering på gruppe-, slekt- eller 

artsnivå. Det ble fokusert på kjente problemarter, både med hensyn på sensorisk kvalitetsforringelse av 

vann og evne til å forårsake sykdom. 

Bakteriesammensetning 

Karakterisering av bakteriesammensetningen ble gjort ved TRFLP ved hjelp av polymerase chain 

reaction (PCR) teknikken , og dette er nærmere beskrevet i vedlegg. Identifisering av spesifikke arter ble 

gjort ved å sammenligne DNA-sekvensene som ble funnet i analysen med kjente sekvenser fra ulike 

bakterier, som finnes i internasjonale ”DNA-sekvens” databaser (bibliotek). Det ble fokusert på arter som 

kan være opportunistisk patogene. 

I forbindelse med oppfølgingen av driften av det nye vannbehandlingsanlegget på Oset tok VAV 

daglige analyser av ledningsevne, pH og fargetall. 

Vanntemperaturen er en parameter med stor betydning for biologisk vekst. Temperaturen i vannet som 

ble levert fra Oset vba ble registrert samtidig med prøvetaking. 

RESULTATER 

Hvilken vannbehandling en hadde på ulike tidspunkt i måleperioden illustreres best ved fargetallet på 

rentvannet, som derfor er inkludert i enkelte av figurene under. 

ATP 

Resultatene fra måling av ATP er vist i figur 2-3. 


Figur 2 Resultater fra måling av ATP (x-aksen angir dato og Y-aksen angir ATP-innholdet i vannet) 

Effekten av den nye vannbehandlingen på innholdet av ATP i vannet både ut fra Oset og i 

distribusjonssystemet var stor, med en reduksjon i innholdet av ATP på 80-90 %. Den store reduksjonen i 

ATP på rentvann fra Oset etter endringen i vannbehandlingen tilsier at det er mikroorganismer som 

tidligere passerte behandlingsanlegget som nå holdes tilbake. Det må imidlertid understrekes at rett etter 

klorering i det gamle behandlingsanlegget kan det ha vært betydelige mengder ekstracellulær ATP i 

vannet. Ved desinfeksjon av råvann frigjøres ATP fra de inaktiverte organismene mens den nye 

behandlingen gjør at det meste av mikroorganismene fjernes fysisk før desinfeksjonstrinnet. Ergo kan 

reduksjonen i mengden levende mikroorganismer som følge av ny vannbehandling være mindre enn 

reduksjonen i mengde ATP. Effekten av ekstracellulær ATP burde imidlertid være liten ute i 

endeledningen på Bygdøy. 

Figur 3 Midlere innhold av ATP i perioder med ny og tidligere vannbehandling (x-aksen angir prøvepunkt 

rangert med økende oppholdstid for vannet i ledningsnettet og Y-aksen angir innholdet av ATP i vannet) 


Med den tidligere vannbehandlingen var det en reduksjon i innholdet av ATP som funksjon av 

oppholdstiden i ledningsnettet, noe som også tidligere er målt i ledningsnettet som forsynes fra Oset 

(Hem, 2001). Dette indikerer en viss utdøing av mikroorganismer, eventuelt kombinert med nedbrytning 

av ekstracellulær ATP. Med ny vannbehandling ble det ikke påvist noen slik reduksjon som funksjon av 

oppholdstiden i nettet, noe som kan skyldes det svært lave innholdet av ATP som i utgangspunktet var i 

vannet ut fra Oset. 

Muggsopp 

Resultater fra analyse av muggsopp er vist i figur 4-5. 

Figur 4 Resultater fra kvantitativ analyse av muggsopp (x-aksen angir dato og Y-aksen angir antall 

muggsoppkolonier i vannet) 

De påviste mengder av muggsopp i alle prøver er lavere enn det en erfaringsmessig kan forvente å 

finne i drikkevann. Med det gamle behandlingsanlegget i drift, dvs. i januar og februar, var det en tydelig 

forekomst av muggsopp, mens det med det nye anlegget i drift, dvs. i mars og april, ikke ble påvist noen 

slik forekomst. Denne store effekten av den nye vannbehandlingen på mengden muggsopp i alle 

prøvepunktene viser at muggsopp i hovedsak stammer fra råvannet og ikke som tidligere antatt også i 

betydelig grad fra vekst på nettet. Av de påviste muggsoppene er det spesielt Aspergillus som er 

(opportunistisk) patogene, mens både Penicillium og svartsopp har et allergent potensiale. 

Skaar og Østensvik (2005) undersøkte muggsopp i råvann og rentvann fra Oset og Skullerud og 

konkluderte med at mens reduksjonen pga. den tidligere vannbehandlingen på Oset var marginal 

reduserte vannbehandlingen på Skullerud, vannbehandlingsanlegget som forsyner ca. 10 % av Oslo og 

som har en vannbehandling bestående av koagulering, direktefiltrering og klorering, mengden med drøyt 

80 %. Resultatene av målingene i 2008 og 2009 bekrefter at koagulering og partikkelseparasjon fjerner 

muggsopp effektivt. Mengden muggsopp som ble påvist i vannet i perioder med det gamle 

vannbehandlingsanlegget i drift i 2008 og 2009 var i samme størrelsesorden som det som er rapportert av 

Skaar og Østensvik (2005). 


Figur 5 Midlere mengde muggsopp i perioder med ny (24.02.2009 – 30.04.2009) og tidligere (18.12.2008 

– 17.02.2009) vannbehandling (x-aksen angir prøvepunkt rangert med økende oppholdstid for vannet i 

ledningsnettet og Y-aksen angir antall muggsoppkolonier i vannet) 

Med den tidligere vannbehandlingen var det noe reduksjon i mengden muggsopp som funksjon av 

oppholdstiden i ledningsnettet. Dette indikerer en viss utdøing av muggsopp. Med ny vannbehandling ble 

det ikke påvist muggsopp i drikkevannet i noen av prøvepunktene i perioden februar til april 2009 og bare 

unntaksvis i periodene med ny vannbehandling før desember 2008. 

Slektsdiversiteten endret seg lite som funksjon av oppholdstiden i ledningsnettet. Når resultatene tyder 

på at det er råvannet som er hovedkilden til muggsopp så er ikke den relativt stabile artssammensetningen 

i prøver tatt på samme dag overraskende. 

Bakteriesammensetning 

Prøvene fra Herslebs gate 5 og utløpet fra Oset tatt med henholdsvis det gamle anlegget og det nye 

anlegget i drift ble analysert med hensyn på bakteriesammensetning. Målingene viste at mangfoldet i 

bakteriesammensetningen var 30-70 % større med det gamle anlegget i drift enn med det nye både ut fra 

Oset og i Herslebs gate. Med det gamle anlegget i drift var mangfoldet like stort i de to prøvepunktene 

mens med det nye anlegget i drift var mangfoldet større i Herslebs gate enn ut fra Oset. Det sistnevnte kan 

tyde på enten at biofilmsammensetningen ledningsnettet ennå ikke var tilpasset de nye forholdene og/eller 

at med et relativt rent vann med lite bakterier ut fra Oset vil mangfoldet kunne øke på ledningsnettet også 

når veksten på nettet er tilpasset de nye forholdene. Uansett viser en økning i mangfoldet at biofilmen i 

ledningsnettet kan påvirke mangfoldet i kranvannet. 

Som nevnt tidligere ble det i denne sammenhengen lett spesielt etter arter som kan være opportunistisk 

patogene. Artene Sphingomonas og Legionella samt ordenen Burkholderiales ble påvist i alle prøvene. 

Clostridium og Mycobacterium ble kun påvist med det gamle anlegget i drift og kun i prøven fra Herslebs 

gate. Pseudomonas aeruginosa ble, noe overraskende, ikke påvist. Resultatene indikerer at det kan være 

bakterier som overlevde og/eller vokste i ledningsnettet med den gamle vannbehandlingen men ikke med 

den nye. Det må understrekes at dette kun er basert på én prøve i hvert punkt med henholdsvis ny og 

gammel vannbehandling. 

Resultatene fra DNA-analysene er sammenholdt med databaser for å finne de mest sannsynlige 

spesifikke bakteriene som var i prøven. Det er videre vurdert hvilke av disse som er rapportert å være 

opportunistisk patogene. Av de sistnevnte er Clostridium beijerinckii, Sphingomonas mucosissima, 


Janthinobacterium lividum, Delftia acidovorans, og Aquabacterium sp. Clostridium beijerinckii var 

sannsynligvis i prøven fra Herslebs gate i februar, Janthinobacterium lividum og Delftia acidovorans var 

sannsynligvis i prøven fra Oset i april, Aquabacterium sp. var sannsynligvis i prøven fra Herslebs gate i 

april, mens Sphingomonas mucosissima sannsynligvis var i prøvene fra Herslebs gate og utløpet fra Oset i 

april. 

Øvrige registreringer 

Mikrobiologisk vekst påvirkes sterkt av vanntemperaturen. Grovt sett kan en forvente at maksimal 

veksthastighet for bakterier dobles når temperaturen øker med 10 grader forutsatt at det ikke er noen 

andre begrensninger som for eksempel tilgang på lett nedbrytbart organisk materiale. I de periodene der 

det var stabil drift med henholdsvis gammel og ny vannbehandling, dvs. fra slutten av desember til slutten 

av april, var vanntemperaturen noenlunde stabil på ca. 4 °C. 

Diskusjon og konklusjoner 

Målingene ble gjennomført med det formål å klarlegge hvilken effekt det nye 

vannbehandlingsanlegget har på den kvantitative og kvalitative sammensetningen av mikroorganismene i 

drikkevannet. Det ble tatt prøver i fire prøvepunkter som representerer ulik oppholdstid for vannet i 

ledningsnettet, både for å se om sammensetningen av mikroorganismene i drikkevannet endrer seg når 

vannet transporteres gjennom nettet og for å se om effektene av tidligere vannbehandling på 

sammensetningen vedvarer lenge etter at behandlingen er endret. 

Effekten av den nye vannbehandlingen på den kvantitative mengden mikroorganismer i drikkevannet 

var både rask og tydelig. Mengden muggsopp sank til null ved første prøvetaking 1-2 uker etter at det nye 

vannbehandlingsanlegget ble tatt i bruk, mens mengden ATP sank med 75-90 % avhengig av 

prøvepunktet. Den relativt største reduksjonen i ATP ble målt i utløpet fra Oset der mengden ATP også 

var høyest med det gamle behandlingsanlegget i drift. Den store reduksjonen i ATP på Oset etter 

endringen i vannbehandlingen tilsier at det er mikroorganismer som tidligere passerte 

behandlingsanlegget som nå holdes tilbake, men det må imidlertid understrekes at rett etter klorering i det 

gamle behandlingsanlegget kan det ha vært betydelige mengder ekstracellulær ATP i vannet. 

Analyseresultatene for muggsopp indikerer at med den gamle vannbehandlingen var råvannet en viktig 

kilde til muggsopp i drikkevannet på nettet, og at disse mikroorganismene holdes tilbake og/eller 

inaktiveres i det nye vannbehandlingsanlegget. 

Den kvalitative endringen for bakterier besto dels i at mangfoldet i bakteriesammensetningen sank 

etter at det nye vannbehandlingsanlegget ble tatt i drift og dels i at enkelte arter ikke ble påvist i 

prøvepunktet i Herslebs gate 5 med ny vannbehandling, mens flere andre arter ble påvist både i utløpet fra 

Oset og i Herslebs gate 5 med både ny og gammel vannbehandling. 

References 

Hem, L. J. (2001). Biostabilitet i drikkevannsledninger. Aquateam-rapport 03-032. 

Skaar I., Østensvik Ø. (2005). Muggsopp i vann fra Oset og Skullerud vannverk. 2-18. Oslo, Rapport fra Norges 

veterinærhøgskole og Veterinærinstituttet.. 


Mixed Bed Filtration in Surface Water Treatment 

Heli Härkki*, Kirsi Hiillos **, Vilja Voutilainen*** 

* Helsinki Region Environmental Services Authority, Water Services, Box 310, FI-00066 HSY, Finland, 

heli.harkki@hsy.fi 

** Helsinki Region Environmental Services Authority, Water Services, Box 315, FI-00066 HSY, Finland 

*** National Board of Patents and Registration of Finland, Box 1140, FI-00101 Helsinki, Finland 

Abstract 

Helsinki Region Environmental Services Authority (HSY) provides waste and water management services 

for the more than one million residents of the Helsinki Metropolitan area. HSY produces drinking water at 

three surface treatment plants in Pitkäkoski, Vanhakaupunki and Dämman. The maximum capacity of the 

Pitkäkoski water treatment plant is currently approx. 1.9 m 3 s -1 , Vanhakaupunki approx. 1.5 m 3 s -1 and 

Dämman approx. 0.3 m 3 s -1 . According to the HSYÑs present investment strategy, operations at the 

Dämman water treatment plant will be closed down in the near future. However, this is only possible once 

the capacities of Pitkäkoski and Vanhakaupunki plants are increased. 

At the Pitkäkoski and Vanhakaupunki water treatment processes limewater (Ca(OH)2) and carbon dioxide 

are used to adjust pH and alkalinity of the water. The limewater is produced at the plants from calcium 

oxide (CaO). The production of limewater from burnt lime requires a lot of maintenance and the capacity of 

the limewater production is not sufficient for the increased need in the future. 

In 2009 pilot-scale experiments were conducted in order to study alkalinisation and filtration capacity of 

different limestones, dolomite, and mixed bed filters with limestone and sand in varied rations. The feed 

water came from the full-scale process and had been treated with chemical coagulation (ferric sulphate), 

flocculation and sedimentation. The results showed that even with a very short retention time, the pH of the 

filtrated water increased more in the mixed bed filters than in filters containing only limestone, while 

turbidity remained low. According to the results, mixed bed filter containing 1:3 Nordkalk Parfill 2/1500 and 

2:3 quartz sand was chosen to full scale experiment carried out at Pitkäkoski in 2010 for three months. 

At the full-scale study the water from the sedimentation process was led to the mixed bed filter and for 

comparison to a rapid sand filter. The mixed bed filter reduced particles from water significantly better than 

the sand filter. Reduction of organic matter was similar to the sand filter. The pH, alkalinity and hardness of 

the water increased as the limestone in the filter dissolved. The dissolution rate of the limestone was 

approx. 24 g/m 3 . 

The promising results supported to continue the full-scale study. A one-year full-scale study was 

conducted at the Dämman water treatment plant in 2010-2011 in order to collect information of the 

maintenance, functioning and cost-effectiveness of the mixed bed filter for a longer period of time. 

The studies indicate the mixed bed filtration is a realistic and cost-effective alkalinisation option in a 

surface water treatment process. At HSY, the next step is to plan the implementation and operation of 

mixed bed filtration for the clarified water of the Pitkäkoski and Vanhakaupunki water treatment plants. 


Introduction 

The Pitkäkoski water treatment plant is the largest water treatment plant in Finland, with the capacity of 

7000 m 3 h -1 . Pitkäkoski water treatment plant produces ca. 52 % of the total amount of the treated 

drinking water in the Helsinki metropolitan area. The second largest water treatment plant, 

Vanhakaupunki, has the capacity of 5000 m 3 h -1 which covers ca. 43 % of the total production. The rest 5 

% is produced at the Dämman surface water treatment plant and at two small groundwater plants. The 

capacities of Pitkäkoski and Vanhakaupunki will be increased to 9000 m 3 h -1 during the following years. 

The water treatment processes in Pitkäkoski and Vanhakaupunki are similar. The process consists of 

coagulation with ferric sulphate, flocculation, horizontal sedimentation, rapid sand filtration, ozonation, 

two-step activated carbon filtration and UV and chloramine disinfection. pH and alkalinity are adjusted 

with limewater and carbon dioxide. The first part of the limewater is fed after sand filtration in order to 

raise the pH from 4.9 to 7.3 and the second part is before the purified water is led to the distribution 

network, when the pH is raised from 6.9 to 8.5. (Figure 1) 

Figure 1 Water treatment process 

Limewater is produced from calcium oxide (CaO) at the plant. Lime-burning liberates carbon dioxide 

from calcium carbonate. Calcium oxide reacts with water producing calcium hydroxide (Ca(OH)2). The 

limewater production and limewater pipes at the plants require plenty of maintenance, the reacting basins 

for CaO and water wait to be repaired, modernized and re-sized, the capacity of clarification of limewater 

is insufficient for increased drinking water production and the thermal preparation of calcium oxide and 

alkalinisation with the combination of limewater and carbon dioxide is not an environmentally sustainable 

method. 

The aim of this work was to study whether limestone filtration could be used to replace part or all of the 

limewater needed with limestone. Very few studies have reported on the suitability of limestone filtration 

for low alkalinity surface water. 

The work started in 2009 with two pilot-scale studies and bench-scale studies. The pilot-scale studies 

were conducted at the Pitkäkoski pilot-scale water treatment plant. The work continued in 2010 in fullscale 

at the Pitkäkoski water treatment plant and later in 2010-2011 at the Dämman water treatment plant. 

Addition to a mixed-bed filter, also so called trix-filter containing limestone, sand and activated carbon 

was studied at Dämman. Feed water quality in Dämman differs from the quality of the one in Pitkäkoski. 

This paper covers the analysis of results of the pilot- and bench-scale studies and the full-scale studies at 

the Pitkäkoski water treatment plant. However, the operation and maintenance experiences of the 

Dämman full-scale studies have been taken into consideration while discussing the cost-effectiveness, 

maintenance and mechanical functioning of a mixed-bed filter. 


Materials and Methods 

Pilot-Scale Studies at Pitkäkoski Pilot Treatment Plant 

The pilot-scale studies were conducted at the Pitkäkoski pilot-scale water treatment plant in two phases in 

2009. The pilot-scale water treatment plant has two identical process lines. The process consists of 

coagulation with ferric sulphate, flocculation, vertical sedimentation, rapid sand filtration + additional 

column for another filtration material, ozonation, activated carbon filtration and UV disinfection (Figure 

2). 

Figure 2 Process flow sheet of the pilot-scale water treatment plant 

Instead of producing water for the filtration process at the pilot-scale plant, the water was taken from the 

full-scale process. In the first pilot-scale run sand-filtrated water was led to the plant and for the second 

study the water for filtration was clarified water from the sedimentation process. Nothing was added to 

the water before filtration. 

The water to be filtrated was led to the additional column filled with a chosen filtration material. The 

inner diameter of the column was 16 cm and the height of the filter material 83 cm, giving contact time 

(EBCT) of 10 min per column with a flow rate 0.1 m 3 h -1 . 

Summary of the quality of the water to be filtrated is described in table 1 and the characteristics of the 

filter material are described in table 2. 

Table 1 The qualities of the feed waters 

Clarified water Sand filtered water 

pH 4.84 6.4 

Total hardness [°dH] 1.14 2.1 

Alkalinity [mmol/l] 0.03 0.33 

Turbidity [FNU] 0.91 0.12 

Fe [µg/l] 748 - 

TOC [mg/l] 2.90 2.40 


Table 2 The characteristics of the filter materials. 

Lenght of the 

pilot-scale run 

Feed water Filter material 

Line 1 Line 2 

31.7. - 23.9.2009 Sand filtrated water Nordkalk Filtra A2 SMA Mineral calcite 

6.10. - 1.12.2009 Clarified water Sand 1:2 + 

Nordkalk Parfill 

2/1500 1:2 

- Nordkalk Filtra A2, grain size 2.0• •5.0 mm 

- Nordkalk Parfill 2/1500, grain size 0.5• •1.5 mm 

- SMA Mineral calcite, grain size 2.0• •4.0 mm 

- Sand from a full-scale filter, grain size 0.5• •1.0 mm 

Bench-Scale Study at Pitkäkoski 

Nordkalk Parfill 

2/1500 

The bench-scale study included nine columns. The diameter of each column was 5.3 cm. Clarified water 

from the full-scale process was led to the columns with flow rate 13 l h -1 /column giving contact time 

(EBCT) of 10 minutes. Summary of the columns in the bench-scale study is described in table 3. 

Table 3 The nine bench scale columns 

Name of the filter Description 

Clarified water Feed water from the full-scale process 

Sand Sand from the full-scale process (0.5ý 1.0 mm) 

1:2 sand/1:2 limestone layered Sand (0.5ý 1.0 mm), Nordkalk Parfill 2/1500 (0.5ý 1.5 

mm) 

2:3 sand/1:3 limestone mixed Sand (0.5ý 1.0 mm), Nordkalk Parfill 2/1500 (0.5ý 1.5 

mm) 


mm) 


mm) 

Nordkalk small grain size Nordkalk Parfill 2/1500 (0.5ý 1.5 mm) 

Nordkalk large grain size Nordkalk Filtra A2 (2.0ý 5.0 mm) 

SMA calcite SMA Mineral calcite from Gotland (2.0ý 4.0 mm) 

SMA dolomite SMA Mineral dolomite (2.0ý 4.0) mm 

Full-Scale Study at Pitkäkoski 

According to the results of the pilot- and bench-scale studies, limestone Parfill 2/1500 (1:3) mixed with 

sand (2:3) was chosen to full-scale study. The study was conducted full-scale at the Pitkäkoski water 

treatment plant. Limestone was added to a rapid sand filter. The filters have two sides that work parallel. 

The functioning of the mixed-bed filter was compared to the one of a rapid sand filter. The main 

characteristics and dimensions of the studied filters are listed in table 4. 


Table 4 The characteristics of the studied full-scale filters 

The characateristics and dimensions of the studied full-scale filters 

Mixed-bed filter Rapid sand filter 

Filter material CaCO3 Nordkalk Parfill 2/1500, grain 

size 0.5ý 1.5 mm (1:3), quarz sand, 

grain size 0.5ý 1.0 mm (2:3) 

Quarz sand, grain size 0.5ý 1.0 mm 

Two-sided filters One side: widht 3,2 m x lenght 6,7 m, One side: widht 3,2 m x lenght 6,7 m, 

depht 3,3 m 

depht 3,3 m 

Filter bottoms Triton Nozzles 

Bed height 

Bed volume 

1,1 m 

30 m 

1,3 m 

3 + 16 m 3 

55 m 3 

Flow rate (m3/h) 290 290 

Surface loading rate 

(m/h) 

6.7 6.7 

EBCT (min) 10 12 

Effective contact time 

(min) 

4 4.7 

On line- 

pH, turbidity, differential pressure, turbidity, differential pressure, flowrate 

measurements flowrate 

Backwash air + water water 

Feed water to the full-scale process was clarified water coming directly from the settling basins. There are 

four sand filters for each sedimentation basin. The normal flow rate for a sand filter is approximately 120 

m 3 h -1 . The quality of the clarified water remains quite stable in normal process conditions. The average 

quality during the full-scale study can be seen in table 5. 

Table 5 The average quality of the feed water during the study period 

Feed water, clarified water from the full-scale 

process 

Temperature 3.7 

pH 4.9 

Turbidity (FTU) 1.5 

UV-abs. 0.11 

TOC (mg/l) 2.95 

Alkalinity (mmol/) 0.036 

Total hardness [°dH] 1.2 

CO2 (mg/l) 10.1 

One addition of limestone was made to the mixed bed filter during the three-month study period. 


Pilot- and Bench-Scale Studies 

The results of bench-scale and pilot-scale studies were compared in order to find out which of the studied 

filter beds should be chosen to the full-scale studies. 

The examined parameters were alkalinisation capabilities, reduction of turbidity, reduction of dissolved 

iron and organic matter as TOC, UV absorbance and molecular size distribution and the microbiology in 

the filters. The alkalinisation capability means in this case the capability of the filter material to raise the 

pH level, total hardness and alkalinity of the treated water while the amount of CO2 in the water 

decreases. 


In the first pilot-scale run, feed water was sand-filtrated water from the full-scale process. The sandfiltrated 

water was led to the filters containing only limestone. In the second pilot-scale run the sand was 

mixed to the filter material instead of being separate filter and in comparison clarified water was led 

directly to a limestone filter with no sand filtration at all. The filter material and mixed bed proportions in 

the second pilot-scale run were selected according to the bench-scale results. The filter bed in the line 1 

was sand and Nordkalk Parfill 2/1500 (1:2) and in the line 2 Nordkalk Parfill 2/1500. The main results of 

the pilot-scale run 2 are listed in table 6. 

Table 6 Mixed-bed filter vs. limestone filter, feed water clarified water from the full-scale sedimentation 

process 

Feed water 1 

Pilot-Scale Run 2 

Filtered water, L1 2 

Filtered water, L2 3 

aver. aver. s aver. s 

pH 4.84 8.67 0.10 8.58 0.06 

Total hardness [°dH] 1.14 2.7 0.14 2.77 0.14 

Alkalinity [mmol/l] 0.03 0.58 0.04 0.60 0.05 

Turbidity [FNU] 0.91 0.10 0.03 0.10 0.04 

Fe [µg/l] 748 41 26 30 19 

Fe-reduction [%] 94.2 3.7 95.8 2.9 

TOC [mg/l] 2.90 2.67 0.25 2.75 0.26 

1 Clarified water from the full-scale process 

2 Sand and Nordkalk Parfill 2/1500 

3 Nordkalk Parfill 2/1500 

Summary of the pilot- and bench-scale results: 

- Mixed bed filters raised the pH level, total hardness and alkalinity the same or a bit more when 

compared to filters containing only limestone 

- Mixing the sand to the limestone gave higher pH, total hardness and alkalinity when compared 

to keeping the materials separate (sand filtered water + limestone filter) 

- The turbidity reduction was better for clarified water both in the mixed bed filter and in the 

limestone filter when compared to the sand filtrated water 

- Fe-reduction for clarified water was excellent both in the mixed bed and in the limestone filter 

- For TOC-removal, sand filtration gave the best results. Mixed bed filters removed more TOC 

and UV absorbance than limestone filters 

- The bench-scale studies indicated that the 1:3 proportion of sand in a mixed bed is sufficient, 

raising the sand amount didn••t show any significant improvement in the treated water quality 

- The type and grain size of the limestone had an effect on the treated water quality. Nordkalk 

Parfill 2/1500 with grain size 0.5• •1.5 mm gave the best results for the majority of the analysed 

parameters 

According to the results the best choice to continue in full-scale would be the mixed bed filter: sand and 

Nordkalk Parfill 2/1500, where the amount of limestone is either 33 % or 50 %. 

Full-Scale Studies 

The full-scale studies at Pitkäkoski water treatment plant were conducted for a three months period while 

the temperature of the raw water remained below + 4 C. The mixed-bed-filter removed turbidity and Fe 

significantly better when compared to the traditional rapid sand filter. The results are shown in the figures 

3 and 4. 


Figure 3 Turbidity before and after mixed-bed-filtration and sand filtration + limewater alkalinisation 

Figure 4 Fe-residual before and after mixed-bed-filtration and sand filtration + limewater alkalinisation 

The pH of the clarified water is approximately 5 and the iron is dissolved in the water. The results 

indicate that while the alkalinity and pH of the water increases in the mixed bed filter, the iron is 

precipitated and thus the alkalinisation enhances the removal of dissolved iron. 

The results for alkalinisation were promising. During the three months period the results for treated water 

were as follows: pH 8.5• •7.0, alkalinity 0.6• •0.4 mmol/l, total hardness 3.0• •2,3 °dH. The quality of the 

feed water is described in table 5. Limestone was added once during the three months period. 

The mixed-bed-filter removed highly conjugated organic compounds, which absorb UV light, better and 

in a more stable fashion when compared to the traditional sand filter but in TOC removal the reduction 

level was the same or slightly smaller. 


The microbiological quality of the filter media was analysed before adding the limestone to the filter by 

using heterotrophic plate count with R2A agar. The results were below the detection limit. The 

microbiological quality of the filtrated water was analysed twice a week with R2A plate count. The results 

remained continuously below 100 pmy/ml. At the end of the study the levels started to rise. This can be 

explained by the precipitate accumulated slowly to the filter that could function as a medium of growth 

for microbes. The microbial growth in the filter was not considered a problem as the ozonation process 

follows the mixed-bed filtration. 

The true measured consumption of limestone was 24 g/m 3 and the theoretical calculated consumption was 

20 g/m 3 . The mixed-bed filter held turbidity well and needed back-washing less frequently than the sand 

filter. The sand filter was back-washed at least twice as frequently. However the sand filter didn••t have 

the air-washing possibility. At Dämman full-scale studies the time between filter washing was 72 h for a 

sand filter and 110 h for a mixed-bed filter. Air-washing was possible for both of the filters. 

The CaCO3 content of limestone Parfill 2/1500 is 94,4 % and the content of insoluble substances is 5,1 %. 

This 5 % cumulates to the filters and functions as a mechanical filter material but needs to be removed 

from the filter at regular intervals. 

The back-washing sequences of the mixed-bed filters need further investigation. In the Dämman fullscale 

study the limestone loss calculated as Ca 2+ ions was approximately 2-4 kg during backwash. 

The cost-effectiveness of the mixed-bed filtration was calculated during the Dämman full-scale study. 

The calculations indicated the total alkalinisation costs would be lower than those of the currently used 

process. However the realization of the total cost savings can only be seen as the consumption, delivery 

and operation methods will be clarified. 

A carbon footprint for burnt-lime, CaO, is 1400 kg CO2/t while for limestone, CaCO3, it is only 17 kg 

CO2/t. The main proportion of the discharge in CaO process comes from the burning process (94 %). For 

limestone the discharge in preparation is 49 %, the rest comes from transport. 

Future of the mixed-bed filtration at HSYÑs water treatment plants 

The mixed-bed filtration is the most promising option for the main alkalinisation method of the 

Pitkäkoski and Vanhakaupunki water treatment plants in the near future. 

The following steps will be the planning of the storage and delivery systems of limestone to the sand 

filters as well as the operation of the mixed-bed filtration as a part of a water treatment process. Optional 

chemical for the pH adjustment of the purified water in the last water treatment step (figure 1) is under 

discussion. 

One mixed-bed filter has been currently taken into use at Pitkäkoski water treatment plant in order to 

collect continuous information of the filtrated water quality as well as the mechanical operation of the 

filter and filter bed. It also allows piloting the most promising delivery systems. 

References 

Voutilainen, V. 2010. Kalkkikivisuodatus pintaveden käsittelyssä. Diplomityö. 

Aaltoyliopisto, Kemian ja materiaalitieteiden tiedekunta. Espoo. 

Zolas, S. (2010). Mixed-bed-suodatus osana vedenpuhdistusprosessia. Diplomityö. Aalto-yliopisto, Insinööritieteiden 

ja arkkitehtuurin tiedekunta. Helsinki. 

Zolas, S. (2011). Suodatintutkimus Dämmanilla. HSY:n sisäinen tutkimusraportti. Helsinki. 



Per-Erik Nyström * , Eva- Marie Abrahamsson ** ,, Christina Nordensten * 

* Livsmedelsverket, per-erik.nystrom@slv.se 

** konsult AKRAB, emma@akrab.se 

Abstract: Drinking water is an essential provision everyday for man. When something goes wrong with the 

drinking water supply, time is always scarce and social crisis at hand. It is therefore important that all who are 

responsible for the acute management of drinking water crises can interact effectively to minimize damage to the 

environment, health and economy. 

In 2011, the National Food Agency (NFA) undertook a program of training and discussion for emergency 

response personnel from police, emergency services, drinking water providers and environmental agencies. The 

training created a common knowledge base about drinking water importance and vulnerability and enhances the 

capabilities of various activities around tasks in drinking water crises and improves the capability for collaboration. 

Since the various occupational groups (civil protection, police, environmental agencies and drinking water 

producers) had the opportunity to meet and educate each other, it did create greater understanding for the many 

existing responsibilities and skills. There are usually procedures for how contacts will be established and clarity of 

roles and responsibilities between these actors. In contrast, no or weak coupling between the three 

aforementioned players and with drinking water producer in connection with an accident and in the acute phase. 

This leads to very unclear roles and responsibilities and the disruption to their good crisis communications in 

connection with a drinking water crisis / disaster. The theoretical studies were supplemented by practical aspects 

through visits to a water works and a final exercise. 

Generally, there are always expected great things from the police at a drinking water crisis / disaster. It's a big 

difference between drinking water producer expectations and what the police are able to provide. Police 

Authority's first task is to investigate possible violations and assist the emergency services on their behalf during 

the emergency phase. The program has identified another key player in the drinking water crisis - SOS alarm and 

its importance in that they have both knowledge of water consumed and the ability to manage water crises. 

The local government capacity to manage water crises in collaboration with key stakeholders has been 

strengthened through training. The ability is interpreted as leadership ability, operational capacity and increased 

understanding of their responsibilities and roles. The participants themselves have estimated that this day of 

training has been of great benefit to them in their future work / role. 

När något går fel med dricksvattenförsörjningen är tiden alltid knapp och samhällskrisen nära. Det är därför 

viktigt att alla som har ansvar för den akuta hanteringen av dricksvattenkriser kan samverka effektivt for att 

minimera skador på miljö, hälsa och ekonomi. 

Under 2011-2013 genomför Livsmedelsverket ett antal utbildnings- och samverkansdagar för insatspersonal från 

polis, räddningstjänst, dricksvattenproducenter och miljökontor. 

Syftet med dagarna är att skapa en gemensam kunskapsbas för flera berörda aktörer inom området dricksvatten 

om vad som kan hända i samband med en dricksvattenkris. Att få förståelse för varandras prioriteringar, roller 

och terminologi i samband med dricksvattenkriser ökar möjligheterna till ett snabbt och korrekt utförande vid en 

akut situation. Genomförandet av dessa utbildnings- och samverkansdagar är ett led i Livsmedelsverkets satsning 

för att stödja kommunernas krisberedskapsarbete inom området dricksvatten. Arbetsformen för utbildningarna är 

ett nytt grepp som Livsmedelsverket nu provar för att höja kunskapen om dricksvatten och dess sårbarhet bland 

de aktörer i kommunerna som kan bli direkt berörda i samband med en dricksvattenkris. 

Utbildnings- och samverkansdagarna planerades av en arbetsgrupp med personer från Livsmedelsverket, 

Sveriges Geologiska Undersökning, (SGU), polisen, räddningstjänsten, Myndigheten för Samhällsskydd och 

beredskap (MSB), Nationella Vattenkatastrofgruppen, (VAKA), kommuner och dricksvattenproducenter samt 

erfarna konsulter från Livsmedelsverkets projektverksamhet. 

Utbildningen skapar en gemensam kunskapsbas kring dricksvattnets betydelse och sårbarhet samt ökar 

kompetensen kring olika verksamheters arbetsuppgifter vid dricksvattenkriser och förbättrar förmågan till 

samverkan i samband med en dricksvattenkris. Genom att de olika yrkesgrupperna (räddningstjänst, polis, 

miljökontor och drickvatten-producenter) får tillfälle att mötas och utbilda varandra så skapas en ökad förståelse 

for aktörernas olika ansvar och kunskap. 

Den teoretiska utbildningen kompletteras med praktiska inslag genom studiebesök på ett vattenverk och en 

avslutande rollspelsövning. Varje yrkesgrupp föreläser i seminarieform för de andra målgrupperna om sina 

uppgifter och sina roller vid en dricksvattenkris. 

Utbildningen genomförs ute vid eller nära ett lokalt/regionalt vattenverk för att kunna genomföra ett studiebesök 

på vattenverket under utbildningsdagen. Många inom räddningstjänstens personal och polisens insatspersonal 

har aldrig besökt ett vattenverk tidigare. Utbildnings- och samverkansdagen avslutas med ett spelat scenario i 


form av ett rollspel och en seminarieövning, där företrädare för de berörda yrkesgrupperna utfrågas om sina 

roller och prioriteringar vid en dricksvattenkris och därefter konsekvenserna av dessa beslut. Övriga deltar som 

publik med möjlighet att ställa frågor och diskutera svaren. 

Under 2011 genomfördes fem utbildningstillfällen och under 2012 planeras ytterligare fem tillfällen från Luleå i 

norr till Karlskrona i söder. De resultat och slutsatser som kan dras efter dessa utbildningstillfällen är att det finns 

bra eller mycket bra samverkan mellan räddningstjänst, polis och miljöförvaltning i samband med en 

dricksvattenkris/olycka under det akuta läget. 

De poliser som deltagit i utbildnings- och samverkansdagarna har i sina utvärderingar sagt att det varit värdefullt 

att få möta dricksvattenproducenten, miljökontoret, räddningstjänst och kommunens säkerhetsavdelning under 

en dag för att diskutera dricksvattenkriser och dess eventuella konsekvenser. 

Det finns vanligtvis rutiner för hur kontakter skall tas och en tydlighet i roller och ansvar mellan dessa aktörer. 

Däremot finns det ingen eller svag koppling mellan de tre ovan nämnda aktörerna och med 

dricksvattenproducenten i samband med en olycka och i det akuta skedet. Detta leder till mycket otydliga roller 

och ansvarsområden samt till försämrade möjligheter till god kriskommunikation i samband med en eventuell 

dricksvattenkris/olycka. 

Det har varit svårt eller mycket svårt att få deltagare från polismyndigheterna till utbildnings- och 

samverkansdagarna. Detta på grund av att polisen är hårt styrda av andra prioriteringar som kommer före i deras 

utbildningsplanering. 

Det har visat sig under de genomförda utbildnings- och samverkansdagar att det finns mycket stora och ibland 

orimliga förväntningar från dricksvattenproducenterna på polismyndigheten och vad de kan bidra med i samband 

med en dricksvattenkris och då framförallt vid hot eller sabotage händelser. Polismyndighetens första uppgift är 

att utreda eventuellt brott och biträda räddningstjänsten i deras uppdrag under räddningstjänstskedet. 

Polismyndigheterna måste prioritera hårt bland de uppdrag de ska ut på och därför är det av största vikt att 

larmningen sker på rätt sätt. 

Dessa utbildnings- och samverkansdagar har identifierat en sedan tidigare ganska anonym aktör i dessa 

sammanhang – SOS-alarm. Den larmoperatör som tar emot larmen, följer ett räddningsindex som styrs av 

kommunens räddningstjänst enligt avtal. Det innebär att det är extra viktigt vad som sägs vid larmningen i 

samband med den här typen av olyckor/händelser. Larmoperatören ställer frågor till den som larmar enligt sitt 

räddningsindex och finns där inga kontrollfrågor avseende drickvatten eller vilka konsekvenser händelsen kan få 

för drickvattnet kommer sannolikt inte dricksvattenproducenten att larmas i ett akutskede. 

Det är av yttersta vikt att de olika berörda aktörerna har både kunskap avseende dricksvatten och förmåga att 

hantera dricksvattenkriser i ett akutskede. 

En reflektion från alla fem utbildnings- och samverkansdagarna och dess övningar är att räddningstjänsten 

snabbt larmas ut av SOS-alarm och är snabbt på plats vid en olycka. Polismyndigheten likaså, därefter larmas 

miljöförvaltning ut till olycksplats av räddningstjänsten eller polisen, då det ingår i deras ordinarie rutiner – men 

inte någon larmade eller diskuterade att snabbt informera dricksvattenproducenten om händelsen! 

Vanligtvis finns inte dricksvattenproducenten ute i ett akutskede som räddningstjänst, polis och 

miljöförvaltningen gör – Beror detta på kunskapsbrist hos de aktuella aktörerna, ett struktur- och 

organisationsmisstag - blir det så här i verkligheten eller är detta bara ett övningsfenomen? 

Kunskapen och resultaten av dessa utbildnings- och samverkansdagar kommer att användas i andra av 

Livsmedelverkets pågående projekt- Aktörsprojektet. Ett projekt som innebär att ta fram ett verktyg/App för 

berörda aktörer i samband med en dricksvattenkris. Verktyget/Appen skall anpassas för att på ett enkelt och 

snabbt sätt underlätta dels det akuta agerandet och hanteringen, dels den mer förberedande planeringen för att 

förhindra en dricksvattenkris. 

Sammanfattningsvis: Den kommunala förmågan att hantera dricksvattenskriser i samverkan med viktiga aktörer 

kan anses ha stärkts genom utbildningarna. Förmågan tolkas då som både ledningsförmåga, operativ förmåga 

och ökad kunskap om varandras ansvarWater quality modelling, monitoring and microbial source tracking och 

roller. Deltagarna själva har gjort bedömningen att denna utbildnings- och övningsdag har varit till stor nytta för 

dem i deras fortsatta arbete/roll 


Increased insight in microbial processes in rapid sandfilters in 

drinking water treatment (DW BIOFILTERS) 

Hans-Jørgen Albrechtsen*, Arda Gülay*, Carson Lee*, Karolina Tatari*, Katie Lin*, Sanin 

Musovic*, Philip J. Binning*, Barth F. Smets*, Rasmus Boe-Hansen**, Peter Borch 

Nielsen** 

* DTU Environment, Technical University of Denmark, Department of Environmental Engineering, 

Bygningstorvet, Building 115, 2800 Kgs. Lyngby, hana@env.dtu.dk. 

** Krüger A/S, Gladsaxevej 363, DK-2860 Søborg 

Abstract. The aim of this research project is to improve our knowledge on biological rapid sand filters as 

they are present in thousands groundwater based water works. This includes molecular investigations of 

the microorganisms responsible for the individual processes (e.g. nitrification); and detailed monitoring and 

experiments in the filters and laboratory to provide insight in the process mechanisms, kinetics and effect 

of environmental factors. Management of the filters (e.g. backwashing, flow rate, carrier type) will be 

investigated at pilot and full scale, supported by mathematical models. The sustainability and climate 

friendliness are evaluated by life cycle assessment (LCA). Molecular methods based on qPCR are being 

developed and implemented to quantify bacteria in different functional groups, such as those responsible 

for nitrification. This allows for development of diagnostic tools to detect if essential or core members are 

present or absent in a malfunctioning filter. It is meaningful to optimize the management of the filter only if 

they are present at relevant concentrations. Furthermore, to get insight in the complexity of the microbial 

community, the full microbial community is being investigated by deep sequencing. This will also contribute 

to a verification of whether the selected qPCR probes include all important groups. Filters from three water 

works have been sampled and are currently being processed to investigate depth profiles and horizontal 

variation in filters. Assays for essential microbial processes such as nitrification and oxidation of 

manganese are currently being established. They will provide identification of controlling parameters, bottle 

necks or inhibition of microbial removal of the bulk compound and the effect of filter management. Finally, 

a pilot plant has been established at Islevbro Water Works (operated by Copenhagen Energy) with 

material from the full-scale afterfilter. After validation that the pilot plant is mimicking the full scale filter, it 

will be used to investigate processes at larger scales such as backwashing procedures and effect of 

increased load of e.g. ammonium, manganese and ferrous iron. This filter will also be used to validate the 

mathematical models build for the biological filters at full scale. 

Introduction 

Thousands of groundwater based waterworks in Denmark and across Europe are using biological rapid 

sand filters. These filters should be seen as bioreactors where microbial processes (removal of e.g. 

ammonia, manganese, ferrous iron, methane, sulfides and natural organic matter (NOM)) are more 

important than the simple physical straining processes. Furthermore, new observations indicate promising 

potentials for degradation of organic micropollutants (pesticides, MTBE, gasoline compounds and 

pharmaceuticals) combined with these processes. 

Unfortunately, most of the underlying microbial processes are poorly understood, which limits the 

management of the filters and which can result in start-up problems and insufficient removal of the 

treated compounds. The aim of this research project is to improve our knowledge on the biofilters by 

molecular investigations of the microorganisms responsible for the individual processes (e.g. 

nitrification); and by detailed monitoring and experiments in the filters and laboratory to provide insight 

in the process mechanisms, kinetics and effects of environmental factors. Management of the filters (e.g. 

backwashing, flow rate, carrier type) will be investigated at pilot and full scale, supported by 

mathematical models. The sustainability and climate friendliness are evaluated by life cycle assessment 

(LCA). 

The overall objective is to improve the process stability and efficiency in drinking water production 

using biological (rapid sand) filters by a strong insight in the microbial processes. Scientifically, the 

project aims at revealing the major microbial actors and their activities in the microbial community, 


understanding the microbial interaction in the microbial community, and determining the major 

parameters which control the presence and activity of the organisms in the technical filter system. 

Material and methods 

To investigate the density of various microbial fractions, qPCR-methods for quantification of 

abundances of ammonium oxidizing (AOB, AOA), nitrite oxidizing (NOB), iron oxidizing (IOB) and 

methane oxidizing (MeOB) microorganisms are established. In addition, PCR - DGGE methods have 

been established to study the diversity within the bacterial and archaeal ammonium oxidizer groups. Filter 

material samples have been sampled from 15 different filters from 4 different water works, and all 

microorganisms analyzed for have been detected. A significant presence of archaeal ammonium oxidizers 

was observed. 

Bioassays have been established to measure microbial manganese oxidation and nitrification – 

one based on a batch setup approach and one based on column approach. Both processes have been 

detected and with rates in the laboratory that are similar to what can be estimated at full scale filters. 

A mathematical model describing the hydraulics, the influence of iron precipitation on 

clogging, and nitrification processes in rapid sandfilters is under development using Multiphysics and 

MATLAB. The Krüger pilot plant (container–size) has been installed at Islevbro waterworks with filter 

material from the filters and coupled to the raw water also supplying the full-scale filter. The pilot plant is 

now in operation and under calibration, with the purpose of validating that it can mimic full scale. 

Overall the experimental conditions (selection of water works, major processes, validation and 

implementation of analytical methods and experimental setups) are in place and the project is now 

producing results. 


The project has 3 main working areas: 1) The presence of the right organisms; 2) Process 

understanding; and 3) Process optimization, evaluation and mathematical modeling at pilot- and full-scale 

level. The aims of these working areas and preliminary results are presented below. 

Presence of the right organisms 

The overall purpose of this WP is to develop, implement and apply tools to investigate if, and at what 

concentration, and with which diversity the expected microorganisms are present in the rapid sand filters, 

– e.g. if nitrifiers are present in a filter which should remove ammonium (NH4 + ) . We are investigating the 

density and diversity of the relevant microorganisms, and link this to groundwater quality, season, and the 

type, operation, and performance of the filters. The underlying hypothesis is that a certain core set of 

microorganisms have to be present at a sufficient density in order for the filter to function optimally. 

To investigate the variability and how to get representative samples for microbial 

investigations , samples of filter material have been collected from 3 waterworks – Islevbro, Sjælsø (with 

two different treatment plants) and Langerød (Holbæk with two unequally performing lines). This 

investigation aims to document vertical (depth profiles) and horizontal variation of microbial abundance 

and diversity in filters. From each waterworks cores of filter material were collected from 3 filters with3 

replicate depth-samples across the filter area. The core samples were divided into 6 depth subsamples for 

DNA extraction. For pyrosequencing purposes, the core samples have only been divided into top layer, 

and a composite sample of remaining depth profiles. 

The research strategy has been to implement molecular methods based on quantitative PCR (qPCR) to 

detect and quantify the number of bacteria in specific functional groups responsible. This allows for 

development of diagnostic tools to detect if essential/core species are present in a malfunctioning filter. 

Only if they are present at relevant concentrations, is it meaningful to optimize the management of the 

filter. However, since the principle here is to test for one specific group, a broader approach (PCR - 

DGGE and 16S rRNA tag based pyrosequencing) is applied to verify that we are using probes covering 

all the relevant groups and species. This effort will also yield insight in the complexity of the full 

microbial community. So far, qPCR-methods for quantification of ammonium oxidizing (AOB, AOA), 

nitrite oxidizing (NOB), iron oxidizing (IOB) and methane oxidizing (MeOB) microorganisms have been 

established, as well as PCR - DGGE methods to study the diversity within the AOB and AOA groups. 


Preliminary results are indicating that the top layers in the filters have a high bacterial content (10 9 /g 

drained wet weight (DWW) of filter material), with abundant AOB and NOB (fractions: 7% and 1%). 

Analysis of AOB amoA genes on the top surface revealed diverse amplicons (9+ bands), indicating that 

the group of bacterial ammonium oxidizers contains several species. With the existing primers, both 

Geobacter- & Lepthotrix-lineage (potential iron- and manganese oxidizing or iron-reducing bacteria) 

were detected in top layer (10 6 and 10 7 /g DWW). Archaeal (based on amoA) abundance and (Total) 

diversity varied with depth in the filters, with highest concentrations in deeper layers. 

The bacterial biomass - measured as extractable DNA from sand grains - varied a) within the 

individual filter, b) between different filters at the same waterworks, c) between different waterworks. T 

his heterogeneity is currently being analyzed. Pre-filters contain more biomass than post-filters at the two 

examined plants at Sjælsø waterworks. 

Process understanding 

The overall purpose of this WP is to investigate controlling parameters for nitrification and 

iron/manganese removal, with emphasis on 1) kinetics; 2) interaction and inhibition of other compounds; 

3) interaction with other microorganisms e.g. grazing by protozoan; 4) effect of carrier or support 

material; 5) Co-metabolic removal of organic micropollutants (e.g. pesticides and pharmaceuticals). 

Nitrification 

Initially a batch set-up was tested based on continuous monitoring of oxygen consumption as 

surrogate for ammonia oxidation. Filter material and water from the reference waterworks were 

investigated in this set up at 10°C, and to prevent mass transfer limitations the batch was continuously 

stirred. Unfortunately oxygen uptake was not sensitive enough to give robust results and repeated spiking 

with ammonium revealed a decrease in ammonium oxidation rates, probably due to physical damaging 

the filter coating during the stirring and therefore this approach was abandoned. Instead a column setup 

with continuous flow has now been developed and this set up is equipped with a new ammonium 

electrode allowing for continuous monitoring of the ammonium concentration. This approach is showing 

promising results. Several trace experiments have revealed reproducible breakthrough curves verifying 

consistent hydraulic conditions in the system. 

Investigations and sampling at the waterworks is providing data on nitrification at full scale level. An 

in situ multilevel sampler has been installed in the filter at Islevbro waterworks allowing us to follow the 

ammonium concentration over depth and estimate nitrification rates - to be compared with batch 

investigations. Preliminary results indicate that nitrification is predominantly occurring in the top of the 

filter. 

Manganese removal 

A bacth set-up has been set up to investigate for manganese removal. The first period has focused on 

measuring methods to be able to distinguish between the different redox stages of manganese. A 

combination of either ICP or AAS and a spectrophotometric method based on a reaction with 

leucoberbelin is now established. In combination with acid extractions of the sediment these methods can 

also be used to characterize the coatings of the sediment. Another aspect has been to identify approaches 

to distinguish between microbial Mn-oxidation and autocatalytic oxidation – and high dosages of sodium 

azide seem to be most effective to create abiotic conditions. It has been surprisingly difficult to inhibit the 

microbial activity in manganese oxidation and thus to distinguish between microbial and autocatalytic 

oxidation with the filter material investigated so far. 

Preliminary results from batch investigations performed with filter material collected from different 

filter depth show decreasing manganese removal from the water phase down through the filter. Microbial 

manganese removal is occurring, but the autocatalytic oxidation appears to be relatively high whereas 

sorption seems limited. Investigations of the effect of ammonium and iron on the manganese oxidation 

showed that ammonium (alone) had no clear effect on manganese removal at investigated concentration, 

but iron (alone) has a negative effect on manganese removal (at least below upper layer). There was no 

detectable effect of interaction between iron and ammonium on manganese removal. 

Investigations and sampling at the waterworks is providing data on manganese removal at full scale 

level. An in situ multilevel sampler has been installed in the filter at Islevbro waterworks to monitor the 

concentration of dissolved manganese over depth and to estimate oxidation rates. The field test results are 


compared with batch investigations. Preliminary results indicate that manganese removal is 

predominantly occuring in the top of the filter. Some of the water supply partners have experienced that it 

can be very difficult to start manganese removal in new water filters and that microbial processes are 

essential in that phase. 

Degradation of pesticides 

Pesticide degradation experiments have been performed in batch investigation with filter material from 

Islevbro waterworks and the two plants at Sjælsø waterworks. The investigated four pesticides (MCPP, 

bentazone, Glyphosate and 4-nitrophenol showed removal (10-90% after 5 hours) with filter material 

from all plants, but mineralization was only observed with filter material from Sjælsø waterworks. It is 

particularly interesting that bentazone are microbially degradable in rapid sandfilters. 

Process optimization, evaluation and mathematical modeling at pilot- and full-scale level 

The overall purpose of this WP is to integrate the knowledge achieved from the other WP’s at the large 

scale and to evaluate the environmental sustainability of the process. Since hydraulic aspects are scale 

dependent, the management of filters will be investigated at various scales. The investigations will 

include the effect of hydraulic conditions on filter performance, such as filter velocity, residence time, 

and stagnation of water in the filters. Another aspect to be investigated is the importance of operational 

parameters on the biomass distribution with depth, e.g. backwashing (intensity/frequency and 

air/air+water/water), shifts in the combination of raw water, stagnation of the water in the filters and the 

load on the filters. These investigations will be based on spatial microbial profiling, mass balance 

measurements and tracer studies. 

The activities in this WP will include investigations in some of the involved water supplies sand filters 

at large scale, and investigations at pilot scale at the partner Krüger A/S’ pilot plant. 

To integrate the knowledge, a mathematical model for biological sand filters will be established using 

the modeling tools Multiphysics and MATLAB. The models will implement the process understanding 

obtained in WP2 (including kinetic parameters, load/performance relationships) and results from the large 

scale investigations and modeling may give a feedback to WP2 in term of further investigation of 

identified bottlenecks. 

A mathematical model describing the hydraulics, the influence of iron precipitation on clogging, and 

nitrification processes in rapid sandfilters is under development. 

The Krüger pilot plant (container-size) has been installed at Islevbro waterworks (reference 

waterworks), established with filter material from the waterworks filters and coupled to the raw water 

also supplying the ‘real’ filter. The pilot plant is now in operation and under calibration, with the purpose 

of validating that it can mimic full scale filter perfomance. The setup has been equipped with automatic 

sampling by on-line sensors of the inlet and outlet of each of the two pilot columns (flow, pressure, 

temperature, dissolved oxygen, electrical conductivity, and turbidity). Data are collected by using 

software lab view, allowing data access, monitoring and control over the internet. Water and filter 

material have been collected at various locations in the column allowing for comparisons with similar 

measurements in the ‘real’ filter. Once it is shown that the pilot plant mimics the full scale filter, they will 

be used to investigate selected effects e.g. increasing load of iron at a large scale, which cannot be 

investigated in the real filters. This will also include the use the methods developed in WP1 and WP2. 

To evaluate the environmental impact and sustainability of biological rapid sand filters it will be 

analysed with respect to Life Cycle Assessment (LCA). This work has been initiated but the major task 

on this is planned to start later in the project. 

Societal and industry impact 

A close collaboration has been established with the water sector and industry to provide an efficient 

knowledge exchange. For example with Krüger a/s on the use and running the pilot plant, and with the 

water companies e.g. the use of KE A/S’ water work Islevbro for reference full scale filter, being used for 

sampling and monitoring. Sampling at water works among the partners is also included. 

Furthermore, the international industry partner – Weber – is supporting to the project by providing 

newly developed filter materials for investigations in the project. 


To optimize the interaction with industry two of the PhD’s have employees from Krüger A/S as 

formal co-supervisors, and exchange of students are occurring between the different partners, e.g. at 

KompetenzZentrum Wasser Berlin (KWB) in Berlin, Germany and at Gent University - UGent, Belgium 

Table 1 Overview of project partners. 

Universities and Knowledge Institutions 

DTU Env 

DTU Man (Prof Michael Hauschild) 

Ghent University, Department of Biochemical and Microbial Technology (Prof. Nico Boon) 

KompetenzZentrum WasserBerlin (TU Berlin, Berlin Wasser Betriebe) 

Industry 

Krüger A/S 

Weber 

Utilities 

Aarhus Vand A/S 

Esbjerg Forsyning A/S 

KE A/S 

Nordvand A/S 

Knowledge transfer 

DANVA 

It is expected that the gained knowledge will improve the companies export potential, and the 

obtained knowledge will be disseminated globally through scientific papers and to the national 

stakeholders by the Danish Water Association. 

This project is conducted by a dedicated, relatively small group in the water sector: one strong 

university, one of the major industry companies, 4 end-users (the major Danish water suppliers), and a 

strong international involvement: consisting of a leading university, a knowledge center and a technology 

supplier. The project has hired 1 postdoc and 4 PhD students. 

References 

See also http://www.dwbiofilters.dk. 


Tracking changes in organic carbon composition during 

drinking water production 

Lavonen, E. * , Tranvik L. ** , Gonsior, M. *** , Ansker, J. **** , Häggström, P. **** , Ericsson, P ***** and 

Köhler, S.J. * 

* 

Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Studies (SLU), Box 7090, 

750 07, Uppsala, elin.lavonen@slu.se 

** Dept. of Limnology, Uppsala University 

*** Dept. of Thematic Studies, Water and Environmental Studies, Linköping University 

**** Stockholm Vatten AB 

***** Norrvatten 

Abstract. The presence of organic carbon can cause problems for drinking water production. In this study 

samples from lake Mälaren, the raw water source for Lovö water treatment plant (WTP), were treated 

using flocculation with alum in bench scale experiments. Results show that concentrations of organic 

carbon in the treated water can be predicted with high accuracy by simple means. Furthermore, ultra-high 

resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to 

investigate the organic carbon composition in samples taken from Lovö WTP. Selective removal of 

relatively unsaturated molecules with high oxygen to carbon ratio was seen during flocculation and after UV 

disinfection and chlorination a large number of new chlorinated organic compounds were detected. 

Introduction 

During the last decades increasing levels of dissolved organic carbon (DOC) in surface waters has been 

reported. For example, in UK lakes and streams included in the Acid Waters Monitoring Network 

(AWMN) there has been an average increase in DOC concentration of 91% since 1988 (Evans et al. 

2006). In southern Norway, WTPs experienced a doubling or even tripling in raw water color during just 

one decade. Furthermore, water color increased more than total organic carbon (TOC) which indicates a 

change in organic carbon composition (Eikebrokk et al. 2004). The production and transport of organic 

carbon from catchments to surface waters is a complex issue and there are multiple hypotheses aiming to 

explain the increased concentrations such as i) increase in runoff intensities leading to intensified carbon 

leaching from the top soil layer (Eikebrokk et al. 2004), ii) increase in temperature with a concurrent 

boost in enzymatic activities resulting in rising degradation rates of soil organic matter (SOM) in 

peatlands (Freeman et al. 2001), iii) CO2 mediated stimulation of primary production (Freeman et al. 

2004) and iv) decreased sulphur deposition affecting DOC solubility through changes in soil water acidity 

and ionic strength (Evans et al. 2005, Monteith et al. 2007). 

Removal of DOC is a key issue in drinking water production from surface waters since organic carbon 

may lead to i) increased color, taste and odor, ii) decreased effect of UV and chlorine disinfection as well 

as, in the latter case, formation of disinfection by-products (DBPs), iii) increased co-transportation of 

harmful substances such as heavy metals and organic pollutants, iv) fouling of membranes and active 

carbon filters and v) increased risk of biological regrowth in the distribution system. 


Prediction of organic carbon removal 

At Lovö water treatment plant (WTP) in Stockholm, Sweden, mean annual TOC in the raw water has 

increased by more than 20 %, from 6.6 to 8.1 mg C L -1 , between 1995 and 2010 (Fig.1). 


Figure 1 Total organic carbon (mg L -1 ) in the raw water of Lovö WTP from 1995 to 2010. Grey dots are 

single measurements while the black lines show the annual mean values. 

In order to investigate the ability of the current treatment process to handle the increasing levels of 

organic matter samples were collected at three locations in the Lovö WTP raw water source lake Mälaren; 

Ekoln (E) (relatively high alkalinity, color and TOC from mostly terrestrial sources), Prästfjärden (P) 

(lower alkalinity, color and TOC with a large contribution from autochthonous sources) and the raw water 

intake at the WTP (mixture between E and P) between late May and December 2011. Surface water was 

treated in bench scale experiments using a Kemira Flocculator with 40, 65 and 90 mg L -1 Al2(SO4)3 

(alum) and results show that DOC in the treated water can be predicted with high accuracy (RMSE = 0.35 

mg L -1 ) according to the following equation 1 (p

working on understanding the small differences in both equations which may be due to i) occurrence of 

particulate carbon at the intake and ii) systematic differences in alkalinity of the raw waters. 

Organic carbon composition 

To investigate potential selective removal by different treatment steps DOC extracted from full scale 

samples was characterized using ultrahigh resolution Fourier transform ion cyclotron resonance mass 

spectrometry (FT-ICR-MS) with electrospray ionization (ESI). The results show an evident 

discriminative reduction of molecules with high oxygen to carbon ratio (O/C) and low hydrogen to carbon 

ration (H/C) during flocculation with alum demonstrating a significant, selective removal of oxygencontaining 

and saturated compounds (p=0.05). This can be visualized using the van Krevelen diagram 

(e.g. Kim et al 2003) where H/C and O/C for the individual chemical formulas are plotted (Fig. 3). 

Furthermore, a large increase in Cl-containing formulas was detected after chlorination. 175 new 

CxHyOzClw where identified which as a group had a significantly lower degree of saturation demonstrated 

by a decrease in H/C and higher DBE (double bond equivalents) as well as significantly more oxygen per 

carbon (O/C) than the already present, Cl-containing organic molecules (p=0.05). Hence, there are clear 

indications that chlorinating water, even at the relatively low doses used in Sweden and with chloramine, 

leads to the formation of by-products that are chemically different from naturally formed Cl-containing 

molecules. We propose studying both chemical and biological reactivity of these by-products further. 

Conclusions 

Our results show that optimizing conditions during flocculation with alum leads to predictive 

concentrations of organic carbon after treatment which can be modeled using only alum dose and organic 

carbon concentration of the untreated water. These results may be used to lower chemical costs and 

sludge production. Furthermore, investigating organic carbon composition in detail using ultra-high 

resolution FT-ICR-MS demonstrates selective removal of nominal formulas with relatively high oxygen 

to carbon ratio and low saturation during flocculation with alum. This type of detailed information can be 

highly valuable when evaluating alternative treatment methods, such as membrane techniques, ionexchange 

and oxidation processes, for WTPs facing the challenge of less treatable, increasing levels of 

organic carbon in the raw water sources. Data from analysis with FT-ICR-MS also show that chlorination, 

even when using chloramine, leads to the formation of a multitude of chlorinated organic compound for 

which further studies are proposed to determine chemical and biological reactivity. 

References 

(a) (b) 

Figure 3 Change in relative abundance during flocculation for a) common and b) lost and produced 

formulas. Bubble size represents the magnitude of the change in relative abundance. 

Eikebrokk, B., R. D. Vogt, et al. (2004). NOM increase in Northern European source waters: discussion of possible 

causes and impacts on coagulation/contact filtration processes. Water Science and Technology 4, 47-54. 

Evans, C. D., D. T. Monteith, et al. (2005). Long-term increases in surface water dissolved organic carbon: 

Observations, possible causes and environmental impacts. Environmental Pollution 137, 55-71. 

Evans, C. D., P. J. Chapman, et al. (2006). Alternative explanations for rising dissolved organic carbon export from 

organic soils. Global Change Biology 12: 2044-2053. 


Freeman, C., C. D. Evans, et al. (2001). Export of organic carbon from peat soils. Nature 412,785. 

Freeman, C., Fenner N., et al. (2004). Export of dissolved organic carbon from peatlands under elevated carbon 

dioxide levels. Nature 430, 195-198. 

Kim, S, Kramer, R.W., Hatcher, P.G. (2003) Graphical method for analysis of ultrahigh-resolution broadband mass 

spectra of natural organic matter, the van Krevelen diagram. Analytical Chemistry 75, 5336-5344. 

Monteith, D. T., Stoddard J.L., et al. (2007). Dissolved organic carbon trends resulting from changes in atmospheric 

deposition chemistry. Nature 450, 537-540. 


Bacterial community analysis of drinking water biofilms in 

southern Sweden 

Katharina Lührig 1*,2 , Björn Canbäck 1 , Tomas Johansson 1 , Anders Tunlid 1 , Kenneth M. 

Persson 1,2 , Peter Rådström 1* , Lund University 1 and Sydvatten AB 2 , Sweden 

*Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, 

Sweden, katharina.luehrig@tmb.lth.se 

The overall objective of this project is to elucidate how changes in the quality of drinking water can 

be related to the quality of the incoming water and changes in the biofilm in the distribution 

system. Biofilms in drinking water pipes are often ignored or simplified in black-box models. But 

advancement in microbiological analysis can be applied to enlighten the system. A changed raw 

water quality caused drinking water quality problems in certain areas of the distribution system, 

like the occurrence of red water. Changing the raw water source can cause red water and the role 

of microorganisms in this process is not fully understood (Li et al, 2010). In this paper, an analysis 

of the bacterial community at different locations in the distribution system of Sydvatten, NSVA and 

VA SYD is presented. Bacterial communities in drinking water can be analyzed by high-throughput 

sequencing of biofilms from water meters (Hong et al, 2010). This approach is presently used to 

compare communities from different areas in the distribution system and to investigate their 

influence on the quality of water. Biofilms from water meters and pipes were sampled in March 

2011 at different spots of the drinking water distribution system. DNA of biofilm material from four 

water meters and two pipes was extracted with the FastDNA Spin Kit for Soil (MP Biomedicals) and 

the bacterial 16S rRNA gene was amplified using the general primers 27F and 534R (Hong et al, 

2010). The amplicons were pyrosequenced on a Roche 454 GS-FLX Titanium instrument. Around 

100 000 reads were obtained for each sample. Preliminary results showed major microbial flora 

differences between samples representing good and poor water qualities. Preliminary assessment 

of the established methodology using improved sampling, DNA extraction and DNA amplification 

procedures showed high reproducibility. The method is promising for an improved understanding 

of the microbial ecology in drinking water distribution systems and particularly useful for 

comparing bacterial community ecology during and after water quality change. This project is 

carried out as a joint venture between Lund University, Sydvatten, VA SYD and NSVA with financial 

support from the Swedish Water & Wastewater Association. 

Introduction 

The quality of drinking water is affected by microorganisms occurring naturally in drinking water 

distribution systems (DWDSs) and the natural chemical composition of the raw water (Persson, 2009). 

Microbial growth in DWDSs can sometimes cause problems, both for the water company, in the form of 

corrosion, and for the consumer, in terms of unpleasant odour or taste (Li et al., 2010; Scott and Pepper, 

2010). In the worst case, consumers’ health may be affected. Furthermore, deterioration in drinking water 

quality may have severe impact on food processing facilities and potentially upon public health (WHO, 

2008, Guidelines for Drinking-Water Quality; 98/83/EC, Drinking Water Directive). Conditions 

favourable for increased microbial growth lead to an increase in biofilm formation, which in turn may 

offer protection against disinfectants intended to remove pathogenic microorganisms. 

The quality of drinking water in the supply network is controlled by each supplier, according to the 

regulations on drinking water laid down by The Swedish National Food Agency. However, conventional 

methods of analysing organic material and nutrients are not sufficient to reveal the microbial growth that 

may take place in the supply network. For this reason, several laboratory methods have been developed 

during recent years to monitor the growth of biofilms in pipelines, directly or indirectly. The potential for 

growth, or the actual growth, can be measured in several ways. One indirect measure that has proved 

useful is active oxygen content (AOC) analysis. A part from analysing indicator organisms, traditionally 

only 3-day heterotrophic plate counts and 7-day slow-growing bacteria have been analysed in water 


supply networks. The numbers of microorganisms detected with these methods are 100 to 1000 times 

lower than the actual number and, at best, provide only a limited indication of the status of the biofilm. A 

direct method found to be successful for the detection of specific microorganisms is ribosomal RNA 

probes. Långmark (2004) used genetic probes to study the development of biofilms on the surface of two 

biofilm reactors in Norrvatten’s distribution system. Recently, bacterial communities in drinking water 

have been analysed by high-throughput sequencing of biofilms from water meters (Hong et al, 2010). 

This project is unique in that it will be possible to follow and document the changes taking place in 

microbial water quality in the supply network when the supply of raw water to the surface water plant, 

Ringsjöverket, was changed from Ringsjön to Bolmen in 2011 using classical methods and highthroughput 

DNA sequencing technologies. Part of the Bolmen tunnel, supplying water from the lake, 

collapsed in 2009 and was closed for repairs, reinforcement and inspection. During this period, drinking 

water was taken from the reserve supply in another lake, Ringsjön. The Bolmen tunnel was reopened in 

March 2011, and water from the lake was again available to about half a million consumers in western 

Skåne. As the quality of the water in Ringsjön and Bolmen is quite different, the changeover from 

Bolmen water to Ringsjö water in 2009 had several noticeable consequences, not least regarding the 

perceived quality of the water by consumers in the areas affected. The drinking water obtained from 

Bolmen appears to be stable, and there is a limited need for maintenance of the broad distribution network 

when Bolmen water is being distributed through it. This level of maintenance is, however, not sufficient 

when Ringsjö water is being used. Increased flushing of the network and monitoring and control of the 

residence time have become important in maintaining high-quality drinking water. The unpleasant smell 

and taste of the water reported by consumers is thought to be related to changes in the biofilm in the 

network. 

Results 

The development of biofilms in water supply networks has been studied previously, although not with the 

intention of actively monitoring and controlling conditions in the network. Few, if any, water utility 

companies use rapid DNA-based measurements to monitor the microbial quality of the water in their 

supply networks. In January 2011, we started to analyse the bacterial communities at different sites in the 

DWDS of southern Sweden in a joint venture between Lund University, Sydvatten, VA SYD and NSVA, 

with financial support from the Swedish Water & Wastewater Association. Seventy-four unique biofilm 

samples were collected in total: 47 samples before the change of the raw water source in March 2011 and 

so far 27 samples after the change. The bacterial community compositions of the biofilms are determined 

using an amplicon pyrosequencing approach (Hong et al., 2010). 

A protocol to extract nucleic acids from various microorganisms originating from DWDS biofilms has 

been evaluated (Hwang et al., 2011) and combined with a novel forensic DNA amplification protocol. In 

collaboration with The Swedish National Laboratory of Forensic Science (SKL), we have recently 

improved the success rate of forensic DNA analysis of “dirty” samples without interfering with the 

composition of the samples as such using pre-PCR processing principles (for a review, see Rådström et 

al., 2004). This method, recently established in routine analysis (Hedman, 2011), was used to generate 

adaptor-flanked amplicons for the Roche 454 GS-FLX Titanium instrument. In collaboration with Dr 

Mats Forsman at FOI, we have chosen a set of primers, already used for amplicon pyrosequencing of 

water meter biofilms, that targets a highly variable ribosomal RNA gene region (Hong et al., 2010). 

A combination of different computer programs is used for data analysis, for example, RDP, CROP and 

RAxML (reviewed by Zinger et al., 2011) in order to characterise the communities and construct 

phylogenetic trees (see Figure 1). Lunarc, the Supercomputer Centre at Lund University, operates some of 

the bioinformatic programs. To date, we have analysed 6 DWDS biofilm samples and 674,000 sequences 

at the Lund University 454/Roche DNA Sequencing Facility. Assessment of the established protocol 

using independent DWDS biofilm samples from similar sites showed very high reproducibility, i.e. 

identical sequence clusters (Lührig et al.). Alpha-, Beta- and Gammaproteobacteria together with 

Actinobacteria, Firmicutes and Bacteroidetes are abundant bacterial groups, reported previously (Eichler 

et al., 2006). Interestingly, preliminary results showed major differences in microbial flora between 


samples representing good and poor water quality before the change of raw water. This is promising for 

an improved understanding of the microbial ecology in drinking water distribution systems, and 

particularly useful for comparing bacterial community ecology during and after changes in water quality. 

Figure 1. A phylogenetic tree showing the inferred evolutionary relationships among various 

bacterial species i.e. clusters, obtained from iron pipe and water meter microbial biofilm samples. 

Discussion 

The presence of unwanted microorganisms in drinking water distribution systems (DWDSs) can affect 

human health, and can also cause quality and safety problems in food production. The microorganisms 

often found in DWDS are usually attached to the inside of water pipes as biofilms, and form complicated 

and resistant natural ecosystems that may even protect and support pathogenic organisms. Due to limited 

access to adequate DWDS samples and the challenges in studying bacterial community structures, current 

information on the microbial diversity of biofilms in full-scale DWDSs is still limited. 

The goal of this project is to elucidate how changes in the quality and safety of drinking water can be 

related to changes in the structures of microbial communities in DWDS biofilms. The specific objectives 

are: (i) to study the microbial ecology of DWDS biofilms, (ii) to identify and exploit microbial 

biomarkers for risk assessment and quality assurance and (iii) to develop a forensic DNA profiling 

approach that can be used to monitor the microbiological quality of water with high-throughput capacity. 

The National Food Agency in Sweden recognizes that planning for long-term drinking water supply in the 

light of changing climate must be improved and systematized, and that research in this area needs 

increased support. Especially important is the review of existing barriers in water production system 

against microbiological water pollution. There is increasing concern about the potential effects of climate 


change which, with altered temperatures and more frequent intense precipitation events, may contribute to 

increased microbial pollution of surface raw water sources. The other increasing threat to water supply 

systems is that the content of humus in surface water reservoirs is increasing. 

At present, the analysis of water is slow and non-specific. As a consequence, pathogenic microorganisms 

remain undetected leading to considerable problems in terms of human illness, and the need for extensive 

sanitizing and water treatment, which has a negative environmental impact. Innovative and novel 

technology must be developed for efficient detection, evaluation and mitigation of microbial 

contamination of drinking water from recipient to consumer. Microorganisms can be protected by other 

microorganisms, and lie dormant until conditions are more favourable, when they return to their 

infectious state. Sediment and biofilms can act as reservoirs for infectious agents, without causing the 

outbreak of disease. Bearing in mind the serious consequences to society of poor-quality drinking water, 

it is of the utmost importance to increase our knowledge and develop methods that can be used to monitor 

the microbial quality of water, directly or indirectly, preferably in real time. 

Acknowledgment 

We would like to acknowledge Sydvatten, VA SYD and NSVA and the Swedish Water & Wastewater 

Association for financial support. 

References 

Eichler S, Christen R, Höltje C, Westphal P, Bötel J, Brettar I, Mehling A, Höfle MG (2006) Composition and 

Dynamics of Bacterial Communities of a Drinking Water Supply System as Assessed by RNA- and DNA-Based 

16S rRNA Gene Fingerprinting. Appl Environ Microb 72: 1858-1872 

Hedman, J. (2011) DNA Analysis of PCR-Inhibitory Forensic Samples, Doctoral thesis, Division of Applied 

Microbiology, Lund University 

Hong PY, Hwang CC, Ling FQ, Andersen GL, LeChevallier MW, Liu WT (2010) Pyrosequencing Analysis of 

Bacterial Biofilm Communities in Water Meters of a Drinking Water Distribution System. Appl Environ Microb 

76: 5631-5635 

Hwang C, Ling F, Andersen GL, Lechevallier MW, Liu WT (2011): Evaluation of Methods for the Extraction of 

DNA from Drinking Water Distribution System Biofilms. Microbes Environ. 2011 Nov 10. [Epub ahead of print] 

Långmark J (2004) Biofilms and microbial barriers in drinking water treatment and distribution, PhD thesis, 

Department of Land and Water Resources Engineering, Swedish Royal Institute of Technology (KTH) 

LeChevallier MW, Schulz W, Lee RG (1991) Bacterial nutrients in drinking water. Appl Environ Microbiol 57: 857- 

862 

Li D, Li Z, Yu JW, Cao N, Liu RY, Yang M (2010) Characterization of Bacterial Community Structure in a Drinking 

Water Distribution System during an Occurrence of Red Water. Appl Environ Microb 76: 7171-7180 

Lührig K, Canbäck B, Johansson T, Tunlid A, Persson KM, Rådström P. Bacterial community analysis of drinking 

water biofilms in southern Sweden. Manuscript in preparation. 

Persson KM. 2009. Tap, tank or bottle? – aspects of drinking water consumption, Formas, Drinking Water - Sources, 

Sanitation and Safeguarding. 

Scott, B. A., Pepper, I. L. (2010): Water distribution systems as living ecosystems:Impact on taste and odor, Journal 

of Environmental Science and Health Part A, 45, 890–900 

Rådström P, Knutsson R, Wolffs P, Lövenklev M, Löfström C (2004) Pre-PCR processing: strategies to generate 

PCR-compatible samples. Mol Biotechnol. 26:133-146 

Sjödin A, Svensson K, Lindgren M, Forsman M, Larsson P (2010) Whole-genome sequencing reveals distinct 

mutational patterns in closely related laboratory and naturally propagated Francisella tularensis strains. PLoS 

One. Jul 19;5(7):e11556 

Stenström TA, Szewzyk U. 2004. Mikrobiell tillväxt – från råvatten till kran i dricksvattensystem. VA-Forsk Rapport 

2004-07 

Zinger L, Gobet A, Pommier T (2011) Two decades of describing the unseen majority of aquatic microbial diversity. 

Mol Ecol. doi: 10.1111/j.1365-294X.2011.05362.x 

Urich, T., Lanzén, A., Qi, J., Huson, D. H., Schleper, C., Schuster, S. C. (2008):Simultaneous Assessment of Soil 

Microbial Community Structure and Function through Analysis of the Meta-Transcriptome, PLoS ONE, Volume 

3, Issue 6, e2527 

Vaz-Moreira, I., Nunes, O. C., Manaia, C.M. (2011): Diversity and Antibiotic Resistance Patterns of 

Sphingomonadaceae Isolates from Drinking Water. Appl Environ Microb 77: 5697–5706 


Membrane fouling as revealed by advanced autopsy in a 

UF/coagulation pilot trial for enhanced NOM removal 

Keucken*, A.; Donose**, B.C.; Persson, K.M.*** 

* Vatten & Miljö i Väst AB (VIVAB), Box 110, 311 22 Falkenberg, Sweden 

** The University of Queensland, Advanced Water Management Centre (AWMC), Brisbane, 4072 QLD, 

Australia 

*** Sydvatten AB, Skeppsgatan 19, 211 19 Malmö, Sweden 

Abstract. In the southern part of Sweden a general tendency of browning of the lakes has been noticed. 

On-going climate change has also increased the risk of surface water contamination with pathogens, due 

to increased combined sewer overflows, and increased run-off from land. In the light of these changes, 

VIVAB has decided to evaluate ultrafiltration (UF) membranes for improvement of drinking water quality 

with respect to NOM removal and microbiological barrier effect. A fully automated pilot plant with preprogrammed 

operating modes has been in operation since June 2010 (14 month trial period). Advanced 

NOM characterizations have been conducted from water source to tap and beyond by using Liquid 

Chromatography – Organic Nitrogen Detection (LC-OCD). The strategy of using UF with pre-coagulation 

proved to be successful in removing humic fractions of NOM. Advanced autopsy methods, involving 

Scanning Electron Microscopy/ Energy Dispersive X-Ray Spectroscopy/ Atomic Force Microscopy 

(SEM/EDS/AFM), revealed the topography and elemental composition of the fouling layer. It was noted 

that the coagulant, calcium and manganese silicates were the most abundant compounds found on the 

surface of the fibres. These results, in combination with the feed characterisation, establish the baseline of 

a future optimisation strategy. The application at full scale of UF/coagulation could meet the requirements 

for multiple microbial safety barriers as well as preparedness for future deterioration of raw water quality by 

enhanced NOM-removal. This concept also minimizes the risk of formation of disinfection by-products 

during the treatment process. 

Introduction 

Kvarnagården WTP, located in Varberg, is the largest municipal water treatment plant for the 

municipality of Varberg. The facility is owned by VIVAB, a municipal company, responsible for 

operation and maintenance of the municipal water supply, waste water treatment and waste disposal 

management. The raw water to Kvarnagården WTP consists of 80% surface water and 20% groundwater. 

The surface water source is an oligotrophic lake surrounded by mixed woodland. The lake has a water 

volume of approx. 61.1 million m3, and a theoretical turnover equivalent to 7.4 years. The long retention 

time has contributed to low humic content consisting mainly of colourless fulvic acids. In line with the 

ongoing browning of lakes and rivers in large parts of Scandinavia, a rising trend in colour and COD has 

been also observed in the surface water abstracted by Kvarnagården WTP. No significant reduction of 

humic substances is achieved with the current treatment process at Kvarnagården WTP, because the 

drinking water guidelines are complied with using filtration and disinfection only. Due to long-term 

trends in the raw water quality, as well as new demands on the microbiological barriers, a pilot scheme 

was initiated including ultrafiltration in combination with coagulation for enhanced NOM removal. The 

effects on NOM concentrations and composition were investigated by far-reaching NOM characterization 

from source to tap. The complex phenomena taking place at the surface of materials used for water 

filtration are revealed these days by advanced autopsy techniques used in the case presented here, in 

which polysulphone membranes used in ultrafiltration combined with coagulation are subjected to 

investigation. The present study aims at presenting a series of results from the advanced autopsy of 

membranes used in UF pilot trials with different operating modes. 

Research objectives 

Investigations of hollow fibres used in long-term UF pilot tests combined with coagulation have been 

performed with advanced autopsy regarding aspects such as morphology of membrane surface and 

elemental composition of the fouling layer. Autopsy techniques such as SEM/EDS and AFM/AC Mode 

topography were conducted on samples extracted from different layers of a Koch PMPW-module. 


Methodology 

Pilot plant for ultrafiltration. The test facility consisted of three process steps: In-line coagulation 

(optional), Pre-filtration and UF. The pilot plant was fully automated and equipped with various sensors 

for on-line measurement of pressure, temperature, flow, turbidity. Feed water for the test facility was 

taken directly from the incoming raw water pipe, in order to obtain representative experimental results in 

terms of composition and pressure of the raw water. Coagulants could be added flow proportional to the 

raw water with subsequent static mixing. Pre-filtration was done by a pressurized fibre-filter, 3FM ® 

(Flexible Fibre Filter Module), with a cut-off of 5-10 microns. The UF pilot plant was equipped with a 

Koch HF 10-48-35-PMPW membrane module, containing 20,000 fibers with a diameter of 0.9 mm. The 

polysulfone membranes had a nominal Molecular Weight Cut-off (MWCO) of 100.000 Daltons, 

corresponding to a pore size of 0.05 microns. The membrane area of the pilot module was 52.4 m 2 and the 

maximum allowable flux 115 l/m 2 *h. The maximum allowable Trans Membrane Pressure (TMP) was 2.4 

bar. Backwashing was carried out automatically at preselected intervals, with or without chemicals. Citric 

acid, sodium hypochlorite or sodium hydroxide were used for Chemically Enhanced Backwash (CEB) 

and for membrane Cleaning in Place (CIP). A typical frequency for CEBs was 60 min with alternating 

acidic backwash (pH ~ 3) and alkaline backwash (pH ~ 12). 

Pilot tests were carried out with different operating modes and in combination with coagulation: 

- Cross-flow with periodic retentate outlet, without coagulation; 

- Pre-treatment by fibre filtering, without coagulation; 

- Direct precipitation without pre-treatment. 

A Poly Aluminium Chloride (PAC) product (Al-content: 7.3%, basicity: 64%) was chosen as coagulant, 

based on results of initial laboratory tests. The feed rate of coagulants during the pilot trials was 1g Al per 

cubic meter of raw water. The coagulant was dosed in-line, with a residence time in the pipe larger than 1 

minute. Rapid mixing of the coagulant was achieved with a static blender. There was no pH-adjustment 

required in conjunction with coagulant dosing. The correct addition of coagulants was monitored by online 

pH measurement. 

NOM characterization. Enhanced NOM fractionation of different water samples was carried out by a 

specialized laboratory, DOC-Labor Dr. Huber in Karlsruhe, Germany. For analysis of NOM, DOC- 

LABOR used LC-OCD (Liquid chromatography – Organic Carbon Detection). Size-Exclusion 

Chromatography combined with three detectors is applied to subdivide the pool of organic matter in the 

water samples into six major sub-fractions which can be assigned to specific classes of compounds 

(Huber et al, 2011). On three occasions, sampling for NOM characterization was conducted from water 

source to tap, and beyond. Sampling dates were chosen based on seasonal characteristics, and the test runs 

of the UF pilot plant. 

Advanced autopsy. Polysulphone membrane fibres, extracted from Koch PMPW 10 modules 

previously used in the pilot setup, have been cut longitudinally and transversally to reveal the three zones 

of interests: lumen side, which is the active filtration area, shell side, on the exterior of the fibre and the 

cross-section. 

AC Mode (intermittent contact) AFM (in air) has been used to profile the lumen and shell side of virgin 

and fouled membranes employing an Asylum Research MFP 3D BIO-AFM (Queensland Node of the 

Australian National Fabrication Facility). The probes used to test the topography were NT-MDT Etalon 

with a nominal spring constant of 3 N/m. Height and Amplitude channels have been used to assess the 

surface features. 

SEM images were collected in secondary electron mode for all carbon coated samples and EDS was used 

to obtain the relative elemental composition of the fouling layer in frame mode, at 5000x magnification 

rates over 60 seconds. SEM/EDS analysis was performed on a Phillips XL-30 (Centre for Microscopy 

and Microanalysis). 

Results 

According to NOM characterizations ultrafiltration combined with coagulation resulted in a significant 

NOM-removal in terms of DOC and humic substances (see Table 1). As expected, ultrafiltration (100.000 

Dalton) with pre-treatment only has no noticeable effect on NOM fractions except for a slight decrease of 

biopolymers. 


Tabel 1 Summary of NOM characterization: UF pilot trials 

All samples have been investigated by SEM/EDS and only reference and fouled membranes have been 

subjected to AFM topographical analyses. The reference sample exhibits typical polysulphone (PS) 

spectra containing O, C, S and sub 1% Cl and Ca. 

According to Figure 1, Height and Amplitude, shell side profiles suggest that in the process of sample 

preparation the membrane structure becomes wrinkled and therefore the images exhibit elongated 

structures, believed to be artefacts. The zoomed-in amplitude signal of 1x1 µm clearly shows the 

amorphous structure of the polysulphone. 

On the other hand, the reference sample on the lumen side, Figure 2, shows pores of few hundreds of 

nanometres and also skewed structures (top side) due to sample preparation. Even though sample 

preparation and handling can affect the final condition of the specimens the important features, such as 

pores, are properly revealed. 

Figure 1 AFM Height and Amplitude (error signal) obtained on “reference” sample on shell side 


Figure 2 AFM Height obtained on reference lumen side sample 

Figure 3 SEM analysis of fouled membrane 

As depicted in Figure 3, the fouled samples exhibit mineral deposition. In comparison with the reference 

sample, additional elements such as: Al, Si, Mn are found by EDS and also it appears that Ca and Cl 

concentration has slightly increased. Multiple scans revealed that similar materials are deposited all 

across the fibre. AFM imaging confirms also the existence of a fouling layer on both sides of the 

membrane, as shown in Figure 4. 

Figure 4 AFM Height obtained on fouled sample on shell side 

As revealed by the AFM imaging in Figure 5, the layer on the lumen side is rough (400nm) in comparison 

with the one of shell side but the nanoscale investigation, shows similar features, which suggests that it 

may be the same material. For both, reference and fouled samples, a conclusion on the organic fouling 

cannot be drawn because of the carbon coating which interferes with the EDS measurements. 

Subsequently, top, middle and bottom samples, depending on their position on the pilot have been 


subjected to SEM/EDS analysis in order to find traces of the fouling material previously observed in the 

case of the fouled sample. 

Figure 5 AFM Height obtained on fouled sample on lumen side 

A comparison in terms of relative elemental concentration is presented in Table 2. It is shown that the 

middle layer has more fouling material in comparison with the top and the bottom (measuring the lumen 

side). The analysis shows also that sample preparation can induce surface artefacts and that they are likely 

to be the result of sample manipulation during preparation. 

Tabel 2 Summary of EDS analyses (elemental weight and atomic 

percentage) 

Conclusions 

SEM/EDS and AFM analyses of KOCH PMPW-10 hollow fibres reveal clearly the shell and lumen side 

structures as well as the structure and elemental composition of the fouling layer. Comparison of samples 

from different sections of the membrane module indicates more fouling material on the middle section 

with respect to the top and bottom layers regarding the lumen side. Considering that the UF membranes 

have been tested in combination with a coagulant it is assumed that the Aluminium and Chlorine found on 

the surface of the hollow fibres to be fractions of the PAC product. The advanced autopsy could not 

reveal signs of membrane deterioration due to hydraulic stress or exposure to chemicals in conjunction 

with recovery cleaning and coagulation. 

References 

Huber, Stefan A, Balz, A, Abert, M, Wouter, P (2011) Characterisation of aquatic humic and non-humic matter with 

size-exclusion chromatography - organic carbon detection – organic nitrogen detection (LC-OCD-OND), 

Water Research 45, 879-885 

Edzwald, J.K. and Tobiason, J.E. (1999) Enhanced coagulation: US requirements and a broader view. Water Science 

and Technology 40(9), 63-70. 

Donose, Bogdan C., (2011) SED/EDS/AFM of UF membranes, Analysis report for VIVAB, AWMC/The University 

of Queensland 


Operational experience from fluidized-bed softening at Bulltofta, 

Bäcklösa, Gränby, Lejsta and Vomb 

Erling Midlöv1), Philip McCleaf2), Britt-Marie Pott3) och Kenneth M Persson4) 

Erling.milov@vasyd.se. VA SYD, Box Box 191, 201 21 Malmö 

Philip.mccleaf@uppsalavatten.se Uppsala Uppsala Vatten och Avfall AB, Box 1444, 751 44 

Uppsala 

Britt-marie.pott@sydvatten.se Sydvatten AB, Skeppsgatan 19, 211 11 Malmö 

Kenneth.m.persson@sydvatten.se Sydvatten AB, Ideon Science Park, 223 70 LUND 

Abstract: Water softening is practiced at many of Sweden’s drinking water treatment plants primarily via a 

cation-exchange process. Water softening using a fluidized–bed reactor process has been utilized in 

Sweden since the early 1990’s. The first municipal plant for fluidized-bed reactor softening of drinking water 

was established in 1995 at Lejsta in Uppsala Municipality. Currently, the fluidized-bed reactor process is 

used to soften drinking water at the Bulltofta, Bäcklösa, Gränby, Lejsta, and Vomb treatment plants. The 

plants have many similarities and differences. The article will document the plants’ operational experiences 

and results and discuss the reasons behind similarities and differences. 

At Vomb the water hardness of an artificial groundwater is reduced from 12 dH o to 6 dH o by addition of 

sodium hydroxide. The pellet size is approximately 2 mm. The raw water supply in central Uppsala is 

groundwater consisting of 40 % artificially infiltrated- and 60 % natural groundwater. At Gränby and 

Bäcklösa, water hardness is decreased from 16-17 dH° to 7-8 dH° and the pellets grow to about 1 mm 

before removal. At the Lejsta plant carbon dioxide and radon gas is removed from the groundwater by an 

aeration stage, then the water’s pH is increased from 7,3 to 8,3 by addition of sodium hydroxide. The water 

hardness is reduced from 16 dH° to 6-7 dH° and after the water leaves the reactors, acid is added for pH 

adjustment. At the Bulltofta plant groundwater from the Alnarpsströmmen aquifer is first aerated then 

softened. The water hardness is reduced from 16-18 dH° to 6-7 dH° after addition of milk-of-lime and 

sand. In Gränby, Bäcklösa and Bulltofta the softening process uses milk-of-lime for increasing pH, while 

sodium hydroxide is used at Vomb and Lejsta. 

The plants have different designs and different performances. If lime is used as alkali, a higher pH is need 

to precipitate calcium carbonate, or a longer detention time. The quality or reactivity of the lime is also a 

key factor for effective operation. Many parameters can be varied when optimizing the softening reaction, 

and the possibilities for improving the performance of softening process are rich, but it needs attention from 

the operator. Produced pellets are utilized as construction material or for buffering of lakes and streams 

affected by acid rain. 

Some operational data 

In table 1, some operational data for the waterworks Vomb, Gränby, Bäcklösa, Lejsta and Bulltofta are 

presented. From the table, it is clear that the softening process can be operated with different chemicals, in 

different reactors and at different pH. The main difference comes from the use of alkali. At Vomb, there is 

no need to reduce the total alkalinity in the water, since the alkalinity is about 190 mg/l. But for the other 

plants, the alkalinity is in the range 300-400 mg/l. When softening at Gränby, Bäcklösa and Bulltofta 

plants, lime is added to enhance reduction of alkalinity. The reactors are cylindrical except for Bulltofta, 

where the reactors are slightly conical. 


Table 1: Operational data for the softening plants 

Plant Vomb Gränby Bäcklösa Lejsta Bulltofta 

Used alkali 32% 

sodium 

hydroxide 

Added alkali per 

removed 

Calcium 

(mol/mol) 

Average loading 

rate (m/hr) 

Average 

theoretical 

detention time 

(minutes) 

Produced pellet, 

g/m 3 

Average pH 

target value at 

reactor top 

Reactor height, 

m 

Reactor 

diameter, m 

1,5 g/l, 

Calcium 

hydroxide 

slurry 

1,5 g/l 

Calcium 

hydroxide 

slurry 

25% sodium 

hydroxide 

Calcium 

hydroxide 

slurry 

1,06 1,20 1,20 1,20 1,10 

70 72 72 28 44 

6 7,5 7,5 11 14 

110 412 420 215 513 

8,9 9,7 9,4 8,3 9,0 

7 9 9 5,2 8 

3,3 2,2 2,2 0,5 2,9 

For Vomb, Gränby and Bulltofta, produced pellets are stored in silos for drainage until transported to 

Nordkalk where they are used as a product for buffering of lakes and streams. For Bäcklösa and Lejsta, the 

pellets are used as final cover material on landfills. 

Discussion and Conclusions 

Some observations can be made from the data: The amount of alkali added to remove calcium is similar for 

all the plants. A greater mass of pellets is produced when using calcium hydroxide as the alkali, which 

hardly is surprising. The reactors need higher pH if the detention time is shorter. For Vomb, the average 

alkali surplus as function of produced water for the years 2008-2011 is presented in figure 1. From the 

figure, it is clear that the average used alkali surplus varies with produced water quantities and that slightly 

more alkali must be added when more water per time has to be softnened. 

In figure 2, the pellets accumulated particle size diameter for Gränby, Bäcklösa and Lejsta is presented. 


Alkali surplus (mol OH / mol Ca) 

1,075 

1,07 

1,065 

1,06 

1,055 

1,05 

1,045 

y = 4E-09x + 0,939 

R 2 = 0,9883 

1,04 

0 5 000 000 10 000 000 15 000 000 20 000 000 25 000 000 30 000 000 35 000 000 40 000 000 

Produced water (m3) 

Figure 1: Alkali surplus as a function of the total produced amount water for Vombverket 2008-2011. 

Accumulated amount (%) 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

0 1 2 3 4 5 6 7 

Pellets particle size (mm in diam) 

Figure 2: Accumulated particle size distribution for pellets from Gränby, Lejsta, Bäcklösa and Vomb 

waterworks. 

Gränby 

Lejsta 

Bäcklösa 

Vomb 


As seen in the particle size distribution curve (Figure 2) the pellet size is more likely to be due to how the 

reactors are run and less depending on the type of chemical used to create the reaction. No significant 

difference can be observed between sodium hydroxide plants (Vomb, Lejsta) and calcium hydroxide plants 

(Gränby, Bäcklösa). 

In table 2, data on pellets composition are presented for Bulltofta, Vomb, Bäcklösa, Lejsta, and Gränby. 

The pellet composition is a function mainly of the raw water content, but for all the waterworks, it is clear 

that the used reactor pH mainly precipitates calcium carbonate. Only to a minor extent magnesium is 

removed from the waters. If iron is present in the raw water, the pellets also contain elevated iron 

concentrations. For Bulltofta, where the water has some strontium, also strontium carbonate is precipitated 

with the calcium carbonate. 

The differences in pellets composition between the plants are, as expected, mainly due to the raw water 

quality. When alkalinity needs to be reduced along with the calcium the addition of calcium hydroxide 

slurry results in approximately a doubled amount of produced pellet. 

Table 2: Composition of pellets (mg/kg TS) for the waterworks 

Bulltofta Vomb Bäcklösa Lejsta Gränby 

Cr 0,11

Session 4: Distributionssystem 

Förbättrad läckagekontroll genom 

Dopplerteknik och tryckreglering 156 

On-line-simulering av distributionssystem 

för dricksvatten 161 

Aqua fingerprint – en metod för att karakterisera 

löst organiskt material i dricksvatten 165 

Påverkar lättflyktiga organiska ämnen från 

PEX-rör hälsan? 169 

Identitet och nedbrytbarhet för organiska 

ämnen från PEX-rör i byggnader 173 

Sektionering i Hvidovre Forsyning – planering, 

genomförande och övervakning 176 

Relining av huvudledningar och 

byggnadsinstallationer 184 


Åtgärder för att upprätthålla trycket i ledningsnätet 189 

Inträngning av markföroreningar i 

distributionsnätet 199 

Svensk utveckling av material i kontakt med 

dricksvatten 203 

155

Förbättrad läckagekontroll genom Dopplerteknik och 

tryckreglering 

Tommy Ekblad*, Frida Moberg** 

* Göteborg Vatten, Box 123, 424 23 Angered, tommy.ekblad@vatten.goteborg.se (Contact information for 

author 1) 

** Göteborg Vatten, Box 123, 424 23 Angered, frida.moberg@vatten.goteborg.se (Contact information for 

author 2) 

Abstract. 

Doppler technique for leak detection: 

The traditional methods of leakage detection, which build on the technique of registering/measuring the 

sound which the leak is producing, have large limitations when it comes to leak detection on plastic pipes 

and on mains with dimensions larger than 300 mm, since the properties of the mains strongly reduce the 

audible sound of the leak. That is why it is important to find a new technique which is independent of the 

propagation of the sound. The Swedish Defence Research Agency has developed a technique for 

identifying hidden targets behind walls and within buildings. This method has a potential to be used in 

other fields, such us leakage detection of water mains. Idea and development of suitable equipment for 

leak detection market is being research by FOI Swedish Defence Research Agency together with 

Norrköping Vatten, Tekniska Verken Linköping and Göteborg Vatten. In contrast to radar used for ordinary 

ground penetration this new technique makes it possible to detect the motion of flow variation in water 

from a leak. The principle relays on the fact that variation of water surface creates a Doppler effect like a 

moving target. By modification of the frequency received, the wanted depth of penetration is decided. To 

pinpoint the leak, you measure in checkered pattern on the surface across and along the actual pipe 

section. The advantage with this new technique is the function on any pipe material and dimension. The 

technique is not disturbed of surrounding sounds. Testing in the field gives promising results and clearly 

indicates water flow in ground. Apart from detecting the leak, you can follow the flow of the leak and it’s 

propagation underground. The finished product will be a hand hold unit which will be passed over the area 

above the main. 

Pressure management – adjustment of pressure depending on the zone’s actual demand: 

A large amount of total leakage from the water mains is “hidden leakage”; which does not appear as 

visible bursts. The water pressure in the mains has a direct connection with the burst frequency and the 

amount of the background leakage. In addition to a higher leakage the pressure also gives a higher strain 

on the mains, which can cause bursts. To minimize leakage, and to protect the mains, the pressure needs 

to be adjusted to the topography of each area. One way to adapt pressure for the lower areas in high 

elevated zones is to use pressure reducing valves. New techniques provide the possibility to control the 

outgoing pressure from the pressure reducing valve according to the actual demand of the zone. In the city 

centre of Gothenburg, there is an area from the 1950´s. In 2010 the amount of leakage of the zone was 29 

% or 41 m 3 per day and km, which can be compared to the total leakage of the whole of the Gothenburg’s 

drinking water distribution network which was 23 % or 23 m 3 per day and km in 2010. During 2009 a new 

zone was created in the area, and a flow controlled pressure reducing valve was installed. The pressure 

on the downstream side of the new valve is stabile, and pressure variations from pumps and water tower is 

compensated through the valve. The pressure is decreased more during low demand periods. The flow is 

measured and transmitted to the control system which makes it possible to detect and find an eventual 

leak. The leakage and the burst frequency within the new reduced pressure zone have decreased. 

156 Session 4: Distributionssystem

Utveckling av ny teknik med Dopplerradar för lokalisering av 

rörnätsläckage i mark 

Beskrivning av projektet 

Utveckling av projektet sker i samverkan mellan Svenskt Vatten, FOI, Cinside, Norrköping Vatten, 

Tekniska Verken i Linköping samt Göteborg Vatten. FOI svarar för den övergripande ledningen. 

Inom försvaret har man utvecklat en teknik för identifiering av dolda mål bakom murar och inom 

byggnader. Denna metod har potential att nyttjas även i andra sammanhang, som vid t.ex läcksökning. 

Behovet att lokalisera rörnätsläckage från i första hand trycksatta ledningar ökar i takt med att kraven på 

leveranssäkerhet, ekonomi, vattenkvalitet och energieffektivisering blir högre. Att genom aktiv 

läcksökning tidigt kunna upptäcka och lokalisera ett läckage skapar förutsättning för att planera 

reparationen och för att kunna informera brukarna. Ett dolt läckage kan fortgå under mycket lång tid utan 

att upptäckas. 80 % av allt läckage är så kallat dolt läckage och innebär en risk för förorening av 

dricksvattnet i samband med underhåll och reparation då rörnätet görs trycklöst. 

Dagens teknik utnyttjar i första hand det ljud som en läcka alstrar för att lokalisera ett läckage. 

Förutsättningarna för denna teknik begränsas kraftigt då ledningens material är av plast eller betong eller 

då ledningsdimensionen överstiger 300 mm. I takt med att plastledningar blir allt mer vanligt ökar 

behovet av en ny teknik för att kunna lokalisera läckor. 

Principen för Dopplerdetektion 

Den nya tekniken med Dopplerradar vilken registrerar vattnets flöde under mark kan nyttjas oavsett 

ledningens material eller dimension. Dessutom är metoden oberoende av omgivande bakgrundsljud. 

Vattnets rörelse skapar en dopplereffekt med varierande frekvenser likt ett rörligt mål och kan identifieras 

via avancerad signalbehandling med radar för markpenetration. 

Figur 1. Principen för detektion 

Session 4: Distributionssystem 157

Insamling och resultat av mätdata 

För test och verifiering av tekniken samt för att skapa underlag till funktionsmodell användes en mobil 

mätutrustning för datainsamling i fält. Tester utfördes bland annat på markförlagda ledningar vid Borås 

övningsfält för läcksökning. Mätningarna utfördes på vattenledning i både gräs och asfalt. I ett 

systematiskt rutnät på mark över och utmed aktuella ledningssträckor utfördes ett stort antal mätningar. 

Läckornas storlek varierade mellan 40 och 60 liter per minut. Läckflödet identifierades vid själva 

rörbrotten och på en sträcka av 6 meter utmed ledningen. Anm. Övningsfältets läckor är dränerade. 

Tidigare utförda tester påvisar en tydlig skillnad i uppmätt rörelse då läckan är på- respektive avstängd, se 

figur 2. 

Figur 2. Läcka i testbädd 

Testutrustning 

Funktionsmodell av rörelsedetektor baseras på radardoppler. Utrustningen består av sändarantenn, 

mikrovågsenhet och mottagarantenn. Utformningen bygger på resultatet från mätningarna som utfördes i 

Borås samt kompletterande mätningar. Antennerna placeras på marken och mätningen påbörjas. 2 GHz 

beräknas vara en lämplig frekvens med hänsyn till antennstorlek och markens tranmissionsegenskaper. 

Generellt blir transmissionsegenskaperna bättre vid lägre frekvenser men det försämrar samtidigt 

möjligheterna att detektera dopplerfrekvensen. Även fyllnadsmaterialets egenskaper påverkar valet av 

frekvens. Till exempel innebär sand och grus betydligt gynnsammare förutsättningar än blöt lera som 

medför svårigheter. Tätskikt av asfalt innebär inga problem. 

Tekniken förutsätter vatten i rörelse med dränerande fyllnadsmassor. Förutom att detektera själva läckan 

kan man även spåra andra flöden under mark. Man kan t.ex. leta uppströms då vatten rinner in i 

fastigheter. 

Färdig utrustning för användning i fält beräknas storleksmässigt bli som en större portfölj med en vikt om 

cirka 5 kg. 

Fortsatt utvecklingsbehov 

Det finns behov av fördjupade undersökningar av verkliga vattenläckor där man klarlägger under vilka 

omständigheter tekniken fungerar och vilka faktorer som kan inverka negativt. Hur hanterar man den nya 

tekniken, hur snabbt kan man uppnå ett tillfredsställande resultat och över hur stor yta kan man operera? 

Mätresultat ska kopplas till typ av rörbrott, läckans storlek, ledningens djup, omgivande fyllnadsmaterial 

och rådande temperatur. Man behöver också utveckla möjligheten till valbart frekvensområde för 

optimering under olika förhållanden. 


Tryckoptimering med flödesstyrd reducering för minskat läckage 

Samband mellan tryck och läckage 

En stor det av det totala utläckaget från vattenledningsnätet utgörs av ”dolt läckage”, som inte ger sig till 

känna i form av rörbrott och uppträngande vatten. Vattentrycket i ledningsnätet har ett direkt samband 

med storleken på det ”dolda läckaget”. Förutom att trycket påverkar storleken på läckaget, innebär ett 

högre tryck också en större belastning på rören, vilket kan ge upphov till fler läckor. För ledningar av 

plast, med skador i form av långsprickor, blir sambandet mellan tryck och utläckage större än för 

metalledningar, eftersom sprickan i plastledningen vidgas med ett ökat tryck. Även skarvläckor kan 

vidgas vid ett ökat tryck. För att minimera utläckaget, och för att skona ledningsnätet, är det viktigt att 

anpassa vattentrycket efter varje områdes topografi, så att ledningsnätet inte utsätts för onödigt högt tryck. 

Ett optimalt tryck är när högsta försörjda tappställe inom ett distributionsområde erhåller nödvändig 

trycknivå, vanligen 15-25 mvp. I vissa fall kan erforderligt tryck för brandvatten vara dimensionerande 

för rörnätets trycknivå. Kontroll av ledningsnätets tryck är en av de faktorer som har stor betydelse för 

läckaget. Ett sätt att anpassa trycket för lågt belägna områden är att reducera trycket via en 

reduceringsventil. De traditionellt använda reduceringsventilerna ger inte alltid ett stabilt tryck på 

sekundärsidan, utan släpper ofta igenom ett högre tryck vid låga flöden. 

Figur 3 Faktorer som påverkar ett vattenrörnäts läckage 

Flödesstyrd reducering 

Ny teknik gör det möjligt att styra utgående tryck från en reduceringsventil beroende på aktuellt flöde 

inom zonen. På natten när förbrukningen är låg, och tryckförlusterna i ledningsnätet är små, sänks trycket 

för att öka igen när förbrukningen går upp. På så sätt kan trycket optimeras och läckaget minskas. I 

många fall, inom framförallt zoner med reservoar, är annars förhållandet det motsatta, med ett ökat tryck 

under nattens lågförbrukning då reservoarnivån är hög. Den avgränsade zon som skapas när ett område 

reduceras utgör samtidigt en naturlig mätzon där flödet kan övervakas så att ett ökat läckage inom zonen 

snabbt kan upptäckas och åtgärdas. 

Tekniken med flödesstyrd reducering som en åtgärd för att minska läckage och rörbrott är vanlig i bl.a. 

England och Australien. 


Figur 4 Principen för tryckoptimering med flödesstyrning 

Exempel från Göteborg 

Inom Göteborg finns ett centralt beläget område med bebyggelse från 1950-talet. Området utgör en 

högzon som försörjs via två tryckstegringsstationer tillsammans med en högreservoar. Ledningsmaterialet 

utgörs till största delen av gjutjärn. Inom högzonen bor 35 500 personer och den totala ledningslängden är 

51,5 km. Läckaget inom zonen var 2010 29 % eller 41 m 3 /km och dygn, vilket kan jämföras med läckaget 

för hela Göteborg som 2010 låg på 23 % motsvarande 23 m 3 /km och dygn. 

Under 2009 skapades en ny avgränsad zon inom området, och en flödesstyrd reduceringsventil 

installerades. Den nya zonen togs i drift i juni 2009. Området med reducerat tryck ligger lägre än resten 

av zonen och har tidigare haft ett onödigt högt tryck och fastigheterna hade egna installationer med 

reduceringsventiler. Den nya reduceringsventilen är stabil på sekundärsidan vilket innebär att 

tryckvariationer från pumpar och reservoar försvinner och trycket sänks ytterligare under natten när 

förbrukningen inom zonen går ner. Flödet genom reduceringsventilen mäts och överförs till 

övervakningssystem så att en läcka snabbt kan upptäckas och lokaliseras. 

Läckaget inom den reducerade zonen kan efter reduceringsventilens installation mätas specifikt, och 

ligger på cirka 10 % eller 16 m 3 /km och dygn, vilket är betydligt lägre än för resten av högzonen. 

Eftersom ledningsnätets material har i stort sett samma ålder och material inom den reducerade zonen 

som i resten av högzonen, är det rimligt att jämföra läckaget inom zonerna. Rörbrottsfrekvensen för zonen 

efter det att reduceringsventilen togs i drift, mellan juni 2009 och december 2011, var 2,7 rörbrott/10 km 

och år. Under 5-årsperioden juni 2004 till juni 2009 var rörbrottsfrekvensen inom den nya reducerade 

zonen 4,9 rörbrott/10 km och år. Minskningen tyder på att den nya ventilen varit effektiv i att reducera 

antalet rörbrott. 5-årsmedelvärde för rörbrottsfrekvens för hela Göteborg är 1,7 rörbrott/10 km och år. 


On-line simulation of water distribution systems 

Kia Aksela 

Lic. Sc. (Tech), Aalto University, PO Box 15200, FI-00076 AALTO, Espoo, Finland, kia.aksela@aalto.fi or 

kia.aksela@wspgroup.fi after 1.8.2012 

A prototype for an on-line simulation system has been developed as a part of a joint research project “Real 

time Management of the Water Distribution Systems”. The designed solution for on-line simulation enables 

snapshot or status pictures of water distribution systems. This solution enables automated on-line 

simulation of water distribution networks during normal operation. Moreover it allows the examination of 

real network behavior during disturbance situations such as pipe breaks or contamination events. The 

system has full topological resolution – meaning that all pipes existing in the real network are included in 

the simulation framework. The simulation system can be run automatically on-line, on a selected time 

period, for example hourly or daily, based on real measurements from a network and properties. 

The developed prototype utilizes IT systems commonly used by water utilities, namely the 

Geographical/Network Information System (GIS/NIS), The Supervisory Control and Data Acquisition 

systems (SCADA) and the Customer Information Systems (CIS). It also benefits from an Automated Meter 

reading System (AMR) when possible. In addition the system uses property based water demand models 

when AMR data is not valid or available. As a part of the larger research, methods for modeling and 

predicting water demand have been developed (Aksela and Aksela 2011). These models and related 

techniques are applied in the context of the simulation system. 

The functioning of the on-line simulation system is based on a developed data model and routines applied 

in a database. The database is used to collect continuously changing dynamic data from SCADA and AMR 

systems, as well as to validate, refine and combine the data with demand models and data from CIS. As a 

result, the database solution automatically generates files needed to run simulation software. These files 

are used together with network topology information from GIS to produce on-line simulations of the 

network. The simulation software utilized was EPANET, which models distribution networks and performs 

simulation of the hydraulic and water quality behavior of the piping systems (Rossman 2000). Through the 

use of a solution such as this it is possible to locationally target maintenance and rehabilitation activities 

more efficiently, and find areas of decreased pressure or discover spreading of contaminants nearly real 

time after the location of the original disturbance is fed into the system. 

Challenges associated with the network management 

The condition of different segments belonging to the water distribution network varies according to the 

correctness of the decisions made in the past. The factors that have an influence on the network condition 

are commonly classified as physical, operational and environmental. Thus, the age of the segments of the 

network alone is not very useful factor when defining the need for maintenance or rehabilitation of these 

segments. In one location the network may be at the end of its lifespan and in other it may be in full 

working condition. Due to this, it is very important to pay close attention to the network condition 

management. 

In order to avoid disturbance situations such as leaks, condition management of the water distribution 

networks must be invested in. On the other hand, even if condition management is prioritized, bursts are 

possible and leaks occur. This is due to that it is very challenging to prioritize segments from the network 

as they are located underground. As the coating of the network can not be seen, it is also difficult to 

investigate the inner surface without compromising the service level, water quality or pressure conditions. 

Thus the goals of the network management should be condition management as well as effective 


detection of disturbances and related limiting of the influenced areas or properties in order to minimize 

the number of the customers experiencing lowered service level. 

One way to achieve the goals of the network management is to focus the maintenance and rehabilitation 

resources accurately on those segments having worst condition. It is commonly agreed, that the most 

important sign which indicate on the condition problems is lowered transmission ability. This can be 

consequence of lowered pressure conditions and/or leakages. The traditionally utilized techniques to 

locate leaks are either laborious or not capable of indicating all leaks. Thus, the final results are usually 

modest. In the future, it is essential that more leaks are detected and located in the early phase, hopefully 

before customers notice and report them. This information is very useful when prioritizing the 

rehabilitation actions and for guaranteeing the service level. The goals and means of network 

management are presented in figure 1. The prototype of the on-line simulation system was developed to 

answer to these challenges. The purpose of the system is to detect and preliminary locate leaks as well to 

identify the influenced areas in order to minimize the caused disturbance. 

Figure 1. Goals and means for network management. 

ICT powering to the network management 

Currently, the software systems commonly utilized by the water utilities are Customer Information 

Systems (CIS), Geographical or Network Information Systems (GIS or NIS) and Supervisory Control and 

Data Acquisition systems (SCADA). The information of the first two software systems is slowly 

changing, more static type as the last software treats all the time changing dynamic data. Traditionally, 

the information of these systems is not merged and used together. In the on-line management system the 

data from these different systems is merged in the different resolution levels. Also, Automated Meter 

Reading (AMR) is one of the key components. Related to the automated meter reading, new ways to 

exploit the data were developed. The key idea was the correct treatment of the dynamic measurements 

and the utilization of the data in an on-line system. Further on, the dynamic data was combined with the 

static information. The on-line system can also be used for indirect detection of leaks and in preliminarily 

detecting the location of the leak. The proposed system was developed using a part of the city of 

Hämeenlinna in Finland as a testing network. In total there were about 900 property connections, from 

which about 200 were AMR metered. The total amount of water billed from the study area was 

approximately 350 000 m 3 per year. The main component for leak detection is the database with 

simulation software EPANET. EPANET was used to run extended period simulation of the hydraulic 

behavior of the water distribution network. 


The most important elements of the on-line management system are: 

- sensors, 

- data transfer, 

- data storage, validation and preprocessing, 

- data processing, 

- data utilization and 

- on-line snapshot generation. 

First element needed is the correct hydraulic measurements from the network and from the properties. 

The placement of the hydraulic measurement points should be carefully considered and in the future this 

is one of the challenges of the water utilities. Only so many measurements points are needed which can be 

maintained – incorrect data is even worse than no data. Also it may be advantageous to place the flow 

measurements and the pressure measurements in different locations depending how the data is utilized. 

Flow measurements enable the calculation of the water balance and the leakage water amount can be 

extracted and compared with the values on the past. On the other hand pressure measurements reveal the 

disturbances faster and can be utilized in the alarm system. Automated meter reading on the property 

level is very advantageous when placed in the properties where the water demand is large and varies 

unexpectedly. In practice, it is a good way to avoid false alarms as it excludes leak suspects, which are 

caused by sudden water demand. 

The data transfer from measurement points to the database is the second step in the on-line system. 

Almost all water utilities have SCADA systems which deliver the data from network measurements 

points to the operator’s computer screen. At this point is good to notice that data transfer from properties 

may be much more difficult compared to the data transfer from the network measurement points. It is 

common that water meters of the properties are located in the middle of the houses surrounded by cement 

walls or underground covered with thick metal lids of the wells – without electricity and antennas, 

causing problems for commonly used transfer methods. 

The third step of the on-line system is data storage, preprocessing and validation. It is important that the 

raw data is stored before the conversion to the meaningful format. This enables the examination of raw 

data when development needs occur and better fault detection in case of a malfunction occurring. In the 

validation phase it is important that the timestamps are verified. After that it is good at least check if there 

is data, and that the data is reasonable, for example between some meaningful values, and if there are 

several measurements in the same time span, for example average, minimum and maximum, are in a 

logical order, if the data are random and do not follow some decreasing or increasing pattern and is there 

a difference between the subsequent values. When storing the validated data it is also extremely important 

that all the identification identifiers are unique through the water utility’s all systems, for example the ID 

of certain flow measurement point is the same in the GIS/NIS, SCADA and simulation software systems. 

After these three primary steps are in order and good quality data are delivered the fourth step of data 

processing can be initialized. In this phase the data from different resolutions and from different source 

systems are combined. For example through the combination of the SCADA and AMR data it is possible 

to make the water balance calculations more precise. At this phase, also the modeled, property specific 

demands are combined with other dynamic data. On the other hand in the automated generation of the 

simulation files the data from SCADA, AMR, CIS and GIS are combined. The simpler routines can be 

executed in the database as more demanding calculations need to be performed by the programs outside 

the database. 

The last steps of the on-line management system are data utilization and on-line snapshot formation. In 

the utilization the data should be compared within the different time resolutions, to see if there are 

changes and if there are, how large are they and what does it mean. Through simulation of the normal 


operation it is possible to enhance the knowledge of the network – how the flow directions change in 

certain points during the day and how the network can be operated in a better or more efficient way, for 

example to save energy. On the other hand, when a leak occurs it is possible to discover the influenced 

customers and inform them of the issue. Finally, after a longer period of time, through analyzing the 

simulation results, it is possible to find those pipes where flow is slowly for long periods and direct the 

flushing operations more effectively. Or it is possible to map the areas experiencing frequently low 

pressures and direct rehabilitation resources accordingly. In the Figure 2 the on-line picture of the 

pressure levels from the full resolution simulation are presented. The first picture illustrates a situation of 

normal operation and the second a leak situation. On-line simulation can be used in a similar manner 

when calculating the influence and spreading of quality problems in the network. 

Figure 2. On-line picture from the simulation before leak occurrence and after the leak occurrence. 

Towards better network management 

The prerequisites for an on-line management system are a well managed Customer Information System, a 

Geographical Information System and a Supervisory, Control and Data Acquisition system as well as an 

Automated Meter Reading system applied to properties where water demand varies greatly and 

unexpectedly. During the development process of the on-line network management system it was clearly 

shown that it is possible and worthwhile to develop network management. The proposed system enables 

more effective operation and maintenance as the knowledge of the network behavior increases and for 

example flushing operations can be directed to the segments where flows are constantly low, faster 

detection of disturbances as occurring leaks can be detected in an early phase and enhanced rehabilitation 

planning as it is possible to get more information from the network. In essence, the system enables 

generally more effective utilization of the existing resources and improved service level for the end 

customers. 

References 

Aksela K., and Aksela M. 2011. Demand Estimation with Automated Meter Reading in a Distribution 

Network. Journal of Water Resources Planning and Management, Vol 137, No. 5. 

Rossman, 2000. EPANET 2 Users Manual. United States Environmental Protection Agency. 


AQUA Fingerprint 

– Early warning for contamination of drinking water 

Rasmus Boe-Hansen*, Erik Arvin**, Colin Stedmon*** 

* Krüger A/S, Gladsaxevej 363, 2860 Søborg, Denmark, rab@kruger.dk 

** DTU Miljø, Bygning 113, 2800 Lyngby, Denmark, erar@env.dtu.dk 

*** DTU Aqua, Jægersborg Allé 1, 2920 Charlottenlund, Denmark cost@aqua.dtu.dk 

Abstract 

Regardless of source, all natural waters contain dissolved organic matter (DOM). DOM consists of a complex 

mixture of organic compounds ultimately originating from the degradation of terrestrial and aquatic 

organisms. Little is known about the actual chemical composition of this material as it consists of a vast 

number of compounds at very low concentrations, presenting a considerable analytical challenge. A fraction 

of the organic compounds present in DOM fluoresce. This fluorescence offers a rapid and sensitive method 

for characterizing and tracing organic material in aquatic environments. A major advantage with fluorescence 

spectroscopy is that the instrumentation can be easily adapted for online measurement presenting a method for 

monitoring quantitative and qualitative changes in organic matter. In this study the suitability of using natural 

organic matter fluorescence to monitor the quality of water in various technical systems is assessed. 

In our study wastewater contaminations could be detected in drinking water in dilutions down to 0.2% 

equivalent to the addition of 60 µg C/L. Samples taken from a full-scale distribution network showed that the 

fluorescence signal was largely unaffected by factors related to normal operation; changes in groundwater 

abstraction wells, retention time and filter cycle. 

The results of this study suggest that drinking water systems can be easily monitored using online organic 

matter fluorescence as an early warning system to prompt further intensive sampling and appropriate 

corrective measures (Stedmon et al. 2011). 

Baggrund 

Drikkevandsbranchens udfordringer 

Vandforsyningen i Danmark er udelukkende baseret på indvinding af grundvand, der behandles og 

distributeres uden brug af desinfektionsmidler. Et betydeligt antal af de danske vandforsyninger rammes hvert 

år af forureninger. Det er svært at skaffe samlede og pålidelige oplysninger omkring disse forureninger, da der 

ikke findes en central registrering. En spørgeskemaundersøgelse viste 205 overskridelser af de 

mikrobiologiske parametre fordelt på 185 vandforsyninger i perioden 2000–2002. Undersøgelsen omfattede 

42 ud af de daværende 270 kommuner svarende til 16 % (By- og Landskabsstyrelsen, 2009). 

I de fleste tilfælde konstateres forureningerne ved, at kravværdierne for de mikrobiologiske parametre er 

overskredet i vandforsyningernes rutinekontrol. Forureningerne synes at være forårsaget af kortvarige 

hændelser (f.eks. i forbindelse med kraftig regn), hvor forureningen trænger ind i systemet og transporteres 

gennem ledningsnettet, som en kortvarig puls med høj koncentration. Ofte kan selve forureningskilden ikke 

genfindes − kun sporet efter den, hvilket selvsagt vanskeliggør den nødvendige kildesporing. 

Nogle af hændelserne kunne være undgået ved større agtpågivenhed fra driftsledelsen og bedre 

egenkontrolsystemer. Men alligevel vil forureningshændelser kunne ske, og det er i disse situationer, der er 

brug for early warning systemer til at mindske konsekvenserne ved forureninger og til at forbedre vores 

forståelse af de forhold og hændelser, som fører til forureninger. 


Et effektivt early warning system forudsætter, at målingen sker kontinuerligt, og at fortolkningen formidles 

inden for få minutter. De dyrkningsbaserede mikrobiologiske metoder, der i dag anvendes, som indikation for 

fækale forureninger, er i sagens natur ikke egnede til early warning, da responstiden er for lang (som 

minimum adskillige timer og typisk dage). Simple statistiske betragtninger viser med tydelighed, at en 

vandforsyning, der udelukkende følger myndighedernes krav til overvågning, i bedste fald vil opdage 1–10 % 

af det reelle antal overskridelser (Boe-Hansen et al. 2003). 

Fluorescensmåling 

Drikkevand indeholder altid naturligt organisk stof, der optræder, som en kompleks blanding af 

nedbrydningsprodukter fra terrestriske og akvatiske planter og dyr. En del af de organiske forbindelser er 

fluorescerende, når de belyses, hvilket betyder, at molekylet exciteres når det belyses med én given 

bølgelængde, hvorefter det udsender lys med én længere bølgelængde. 

Når en kompleks blanding af organiske stoffer belyses, er resultatet et unikt ”fingeraftryk”, der afhænger af 

den stoflige sammensætning af puljen. Sammensætningen afspejler i høj grad det miljø, vandet stammer fra, 

f.eks. indeholder grundvand typisk mange humus forbindelser, mens spildevand har et væsentligt indhold af 

aminosyrer. Figur 1 viser fluorescens ”fingeraftrykket” fra to forskellige vandmiljøer. Øverst fra et vandløb 

og nederst renset spildevand. Det fremgår tydeligt af figuren, at sammensætningen af kulstofpuljen medfører 

markant forskellige fluorescensspektre. 

Figur 1. Fluorescens fingeraftryk fra et vandløb (øverst) og renset spildevand (nederst). 

Selvom fluorescensmålingen ikke er en direkte måling af drikkevandets indhold af vira, bakterier og 

protozoer, forventes en nærmere analyse af kulstofsammensætningen at kunne give et deltaljeret billede af 

vandet hygiejniske kvalitet. Dette skyldes, at mikrobiologiske forureninger i praksis altid vil være ledsaget af 

opløst organisk stof, der danner levegrundlag for mikroorganismerne. 

PARAFAC modellering 


Når flere vandtyper sammenblandes vil det resulterende fingeraftryk stadig indeholde information, der kan 

anvendes til at spore blandingens oprindelige vandtyper og blandingsforholdene mellem disse. Til dette 

formål findes en række matematiske og statistiske teknikker, herunder principal komponent analyse (PCA) og 

parallel faktor analyse (PARAFAC). Princippet i PARAFAC metoden er illustreret i Figur 2. 

Figur Error! No text of specified style in document..1. Modellering af fluorescens med PARAFAC 

Med PARAFAC metoden kan fluorescensspektret kan nedbrydes i en række bidrag fra forskellige 

komponenter, hvor det antages, at intensiteten af fluorescensen er lineært afhængig af koncentrationen. 

Komponenterne repræsenterer i denne sammenhæng en modelmæssig fortolkning af spektret og er således 

ikke nødvendigvis et udtryk for specifikke kemiske stoffer. Typisk vil komponenterne afspejle stofgrupper 

kombineret med bidrag fra et eller flere enkeltstoffer. Den specifikke sammensætning af kulstofpuljen er altså 

stadigvæk grundlæggende ukendt og blandingen er for kompleks til komplet karakterisering med eksisterende 

kemiske teknikker. Fluorescensen kan imidlertid på et mere overordnet niveau relateres til nogle 

hovedgrupper af fluorophorer. 

I dette projekt blev den bedste tilpasning af data opnået med en model med 4 komponenter. 

Undersøgelser 

Brug af fluorescensmålinger til early warning forudsætter, at almindeligt forekommende variationer i 

kulstofpuljens sammensætning kan adskilles fra de uønskede hændelser. 

Denne undersøgelserne havde derfor to temaer (Naturstyrelsen, 2011), nemlig: 

- Bestemmelse af flourescensmålingers følsomhed overfor spildevandsforurening 

- Karakterisering af den naturlige og driftsmæssige variation i fluorescensmålingerne 

For at bestemme fluorescensmålingens følsomhed blev en række vandprøver tilsat en kendte mængder 

ufiltreret spildevand. 


Den naturlige og driftsmæssige variation blevundersøgt ved en række målinger på Lillevang vandværk i 

Farum. Lillevang er et traditionelt dansk vandværk, hvor vandet indvindes fra et kildefelt med tre boringer. I 

den normale drift sættes boringerne i drift enkeltvis. Vandbehandlingen består af beluftning, for- og 

efterfiltrering, hvoefter vandet ledes til en rentvandstank. Der blev udtaget prøver efter rentvandsbeholderen 

og i distributionsnettet. 

Undersøgelserne havde til hensigt at karakterisere variationer i fluorescensspektret som følge af driftsmæssige 

forhold, der potentielt kan medføre ændringer i vandkvaliteten. De væsentlige variationer blev vurderet at 

være: 

- Skift af indvindingsboringer 

- Opholdstid i ledningsnet 

- Filtercyclus 

Resultater 

Målingerne og modelleringen viste at der er en stærk korrelation mellem spildevandsmængde og intensiteten 

af modelkomponent F4. Intensiteten af modelkomponent F1 og F2 øges i mindre grad, mens F3 vedbliver 

med at være konstant (se figur 3). 

Figur 3. Sammenhæng mellem intensitet af komponenter og spildevandsmængde i vandprøve 

Det betyder altså, at komponent F3 hovedsageligt er knyttet til drikkevandets naturligt forekommende 

organiske stof i, mens komponent F4 er stærkt korreleret til spildevandsmængden. Forholdet, mellem de to 

komponenter, synes derfor at være en lovende indikator for spildevandsforurening, der må forventes være 

robust i forhold de naturlige driftsmæssige variationer i vandsammensætningen. I undersøgelsen kunne fækale 

forureninger detekteres ned til en koncentration svarende til 0,2 % spildevand med et signifikansniveau på 95 

%. Dette svarer til detektion af 60 µg-C/L med spildevandsoprindelse. 

Målingerne viste, at variationen i fluorescensspektret er lille under normal drift. Skift mellem boringer 

medførte en ændret sammensætning af kulstofpuljen uden at det dog påvirkede følsomheden overfor 

spildevand. Der kunne ikke konstateres en effekt af opholdstid i ledningsnettet og af filterskylninger. 

Referencer 

Stedmon, C.A, Seredyńska-Sobecka, B, Boe-Hansen, R, Le Tallec, N. & Arvin, E. (2011). A potential approach for 

monitoring drinking water quality from groundwater systems using organic matter fluorescence as an early warning for 

contamination events. Water Research 45 (18), 6030-6038. 

Naturstyrelsen (2011). AQUA fingeraftryk - Online detektion og karakterisering af fækale forureninger i vandtekniske 

systemer. 

By- og Landskabsstyrelsen (2009). Undersøgelse af: Mikrobiologiske Drikkevandsforureninger 2000 – 2002, omfang, 

årsager, aktion og sygdom. 

Boe-Hansen, R., Albrechtsen, H.-J., Arvin,E. & Spliid, H. (2003). Mikrobielle forureninger - Vi ser kun toppen af 

isbjerget. DanskVAND (71), 86-90. 

Projektet Aqua fingerprint er udført og finansieret af: Miljø DTU (Danmarks Tekniske Universitet), Afdeling for Marin 

Økologi (Danmarks Miljøundersøgelse), Krüger A/S og By- og Landskabsstyrelsen (Miljøministeriet). 


Påvirker lett flyktige organiske forbindelser fra PEX rør menneskelig helse? 

Av Vidar Lund 1* , Mary Anderson-Glenna 1 , Ingun Skjevrak 2 og Inger-Lise Steffensen 1 , 

Nasjonalt folkehelseinstitutt, Divisjon for miljømedisin, Avdeling for mat, vann og kosmetikk 1 , P.O.Box 4404 

Nydalen, NO-0403 Oslo, Norge, Statoil ASA, NO-4035 Stavanger, Norge 2 

*corresponding author and project leader, e-mail: vidar.lund@fhi.no, tel: +47 21 07 64 43, fax: +47 21 07 

66 86, web site: http://www.fhi.no. 

Abstract. Pipe-in-pipe systems are now commonly used to distribute water in many Nordic homes. The 

inner pipe for drinking water is made of a plastic called cross-linked polyethylene (PEX). 

Previous international studies have shown that plastic pipes can release substances that give an 

unwanted taste and odour to drinking water. It has also been suggested that some of these substances 

may be of health concern. 

The aim of this study was to investigate whether leakage products from these pipes are harmful to human 

health and if they affect the taste and odour of drinking water. These leakage products consist of residues 

of additives used during production to give plastic pipes their desired properties, as well as subsequent 

breakdown products. 

The migration tests were carried out in accordance with EN-1420-1, and volatile organic compounds 

(VOCs) were analysed by gas chromatography-mass spectrometry. The levels of VOC released from new 

PEX pipes were generally low, and decreasing with time of pipe use. Further, no association was found 

between production method of PEX pipes and concentration of migration products. 2,4-Di-tert-butyl phenol 

and methyl-tert-butyl-ether (MTBE) were two of the major individual components detected. In three new 

PEX pipes, MTBE was detected in concentrations above the recommended US EPA taste and odour value 

for drinking water, but decreased below this value after five months in service. However, after one year in 

use the threshold odour number (TON) values for two pipes were still similar to new pipes. 

For seven chemicals for which conclusions on potential health risks could be drawn, this was considered 

of no or very low concern. However, if water was left stagnant in the pipes for a couple of days the odour 

from some of these pipes could negatively affect drinking water for more than one year. 

Innledning 

I de senere år har rør-i-rør systemer kommet inn til erstatning for kobberrør for distribusjon av vann i 

husinterne rørsystemer. Ofte er disse rørene laget av kryssbundet polyetylen (PEX). Relativt lite 

informasjon foreligger vedrørende mulige helseeffekter ved å benytte drikkevann fra slike rør, da dette 

normalt ikke inngår ved testing av rør for bruk til vannforsyning. Da det nå stilles krav om rør-i-rør 

systemer i nye boliger og ved rehabilitering av gamle, er det av interesse å kartlegge mulige helserisiki 

forbundet med bruk av slike materialer, samt om det eventuelt kan gi opphav til lukt- og smaksproblemer 

på vannet. 

Termoplast typer, inkludert PEX, er vist å kunne lekke rester av tilsetningsstoffer som antioksidanter, 

stabilisatorer, limprodukter og deres nedbrytningsprodukter, som er benyttet under produksjonen for å gi 

plastrørene de ønskede egenskaper. Hvilke kjemikalier som inngår er relatert til hvilken prosess som er 

benyttet ved produksjon av PEX rørene, og det er tre prosesser som benyttes, med rør som derfor har fått 

betegnelsene PEX-a, PEX-b og PEX-c (Gätcher and Müller 1990; Brocca et al. 2000 and 2002; Denberg 

et al. 2007; Denberg et al. 2009). Tidligere undersøkelser har vist at PEX rør, under stagnante forhold, 

lekker organske komponenter til vannet, som bl.a. kan gi opphav til biofilmdannelse og lukt- og 

smaksulemper ( Anselme et al. 1986; Hem and Skjevrak 2002; Skjevrak et al. 2005; Skjevrak et al. 2003). 

Kun noen få av disse utlekkingsproduktene er identifisert. Studier har også vist at noen av disse stoffene 

kan være kreftfremkallende i større konsentrasjoner, og at noen opportunistiske patogener kan utvikle seg 

i biofilm i PEX rør, men ikke i kobberrør ( Rogers et al. 1994; Kerr et al. 1999; van der Kooij, 

Vrouwenvelder and Veenendaal 2003) 

Vi ønsket derfor å undersøke de fleste PEX rør på det nordiske marked, for å kartlegge om 

utlekkingsprodukter fra slike rør kunne ha en negativ helseeffekt og/eller en påvirkning på drikkevannets 

lukt og smak. 


Materiale og metode 

Åtte ulike typer PEX-rør som markedsføres på det nordiske markedet ble testet for lett flyktige 

utlekkingsprodukter (VOC) etter en Europeisk Standard test for utlekkingsprodukter fra plastrør (EN 

12873-1 2003). Det ble testet både nye rør og rør som hadde vært i drift i 5 måneder. I tillegg ble en 

rørtype testet i en mindre dimensjon (mindre diameter) for å kunne si noe om hvordan volum til overflate 

forholdet influerte på utlekkingen av lett flyktige stoffer (VOC). Prepareringen av testvannet ble basert på 

CEN EN-1420-1 for testing av organoleptiske egenskaper (lukt- og smak) på drikkevann i kontakt med 

plastrør. (EN 1420-1, 1999). Denne metoden er basert på at vannet står stille i kontakt med rørmaterialet i 

tre perioder á 72 timer, hvorav vannet fra første og tredje utlekkingsperiode ble analysert for 

utlekkingsprodukter, mens vann fra andre utlekkingsperiode ble benyttet til lukt- og smakstest. De testede 

PEX rørene inkluderte både PEX-a, PEX-b og PEX-c rør. Ett polybutenrør (PB), som har vært foreslått 

som et alternativ til PEX rør, ble inkludert i testen for sammenlikning. Etter testing av nye rør, ble alle 

rørene inkludert i et pilotanlegg der strømningsforholdene alternerte mellom stagnante og strømmende 

vann, for å illudere strømningsforholdene i et vanlig bolighus. Magnetventiler åpnet for vannstrømmen tre 

ganger á 15 minutter/døgn. Lukt og smakstester ble utført både på nye rør og på rør som hadde vært i 

bruk i ett år. 

Ultrarent vann, fremstilt av kranvann vha ELGA Purelab Prima med partikkelfilter, forbehandlingsfilter, 

og omvendt osmose enhet, og vidrer gjennom en ELGA Purelab Ultra enhet, bestående av to trinns 

ionebytting, samt UV bestråling ved 254 og 185 nm for fotooksidasjon og ultrafilter som sluttpolering. 

Rørene ble preparert i henhold til EN-1420-1 og fylt med ultrarent vann, tettet i begge ender med 

glasskorker (forvarmet til 450 o C i 2 timer for å fjerne organiske forurensninger på glasskorkene) og 

inkubert ved romtemperatur i 72 timer. Rørene ble så tømt for testvann, som ble lagret på glassflasker, 

forvarmet på samme måte som for glasskorkene, og lagret kaldt til analyser ble gjennomført. Den samme 

prosedyren ble gjentatt 3 ganger for hvert rør, hvorav testvannet fra den andre 72 timers perioden ble 

benyttet til lukt- og smakstest (TON analyse). 

Lett flyktige stoffer (VOC) fra utlekkingstestene ble konsentrert fra 1 L testvann ved ••purge and trap 

method•• basert på ••open-loop stripping•• prinsippet (Skjevrak 1998). For en mer detaljert beskrivelse av 

denne metoden henvises til Lund et al. 2011. Ti referansestoffer ble benyttet for å kvantifisere de ulike 

utlekkingsproduktene. 

Lukt analyse (TON= Threshold Odour Number) ble utført i henhold til EN 1622 (EN 1622 1997), som er 

basert på en kvantitativ fortynningsmetode, basert på fem fortynningstrinn, fra ultrarent vann (TON=0) til 

TON=5. TON verdier >3 karakteriserer vannprøver med tydelig avvikende lukt. 

Tabell 1: Reference compounds used for quantification of migrated compounds: 

Referanse stoff CAS nummer (GC retention time) 

2-metylpropene CAS 115-11-7 (RT 0.95) 

2-metyl-2-propanol CAS 75-65-0 (RT 1.44) 

Metyl-tert-butyl ether (MTBE) CAS 1634-04-4 (RT 1.63) 

2-ethoxy-2-methyl-propane (ETBE) CAS 637-92-3 (RT 2.11) 

Di-tert-butyl peroxide CAS 110-05-4 (RT 4.63) 

5-metyl-2-hexanone CAS 110-12-3 (RT 8.95) 

1,3-di-tert-butyl benzene (1,3-DTBB) CAS 1014-60-4 (RT 22.12) 

2,6-di-tert-butyl phenol (2,6-DTBP) CAS 128-39-2 (RT 27.96) 

2,6-di-tert-butylp-benzoquinone (2,6-DTBQ) CAS 719-22-2 (RT 28.66) 

2,4-di-tert-butyl phenol (2,4-DTBP) CAS 96-76-4 (RT 29.66) 

Risiko analyse 

Den høyeste verdien av VOC fra hvert rør, uavhengig av hvilken av de tre 72 timers periodene dette var, 

ble lagt til grunn ved risikovurderingen av de enkelte stoffene. Som grunnlag for disse risikovurderingene 


le den potensielle helserisikoen vurdert på basis av opplysninger gitt av Verdens helseorganisasjon 

(WHO 2008) eller US EPA (US EPA 1997), dersom opplysninger var tilgjengelige. Nasjonale positiv 

lister for materialer og kjemikalier i drikkevann i Tyskland (Umweltbundesamt, Germany 2009) og 

Nederland (Ministral Regulation, The Netherlands 2007) ble også sjekket og de få grenseverdiene som 

ble funnet der, ble også inkludert i vurderingen. I de fleste tilfellene ble det imidlertid ikke funnet noen 

grenseverdi for de funne stoffene. 

I disse tilfellene ble positiv listen for plastikkmaterialer for kontakt med mat sjekket for grenseverdier av 

de aktuelle stoffene, samt ••the Synoptic Document•• som lister opp slike stoffer (European Commission 

2002, European Commission 2005). For stoffer der det ikke ble funnet noen grenseverdi, ble tilgjengelige 

toksisitetsdata brukt i en risikovurdering for å beregne en tolerabel migrasjon(utlekking) til drikkevann. 

Verdier for ••Akseptabelt daglig inntak•• (ADI) eller ••Tolerabelt daglig inntak•• (TDI) beregnes vanligvis 

ved å dividere verdien for ••Ikke observert effekt nivå•• (NOAEL= Høyeste dose som ikke er vist å ha 

noen tydelig effekt i langtids dyreforsøk) med en Usikkerghetsfaktor (UF). Fra ADI eller TDI verdiene, 

kalkulert fra en NOAEL verdi dividert på UF, ble det så beregnet en TM verdi (Tolerabel 

migrasjon/utlekking). Videre kalkulasjoner er basert på inntak av 2L vann, en kroppsvekt på 25 kg for 

barn og 60 kg for voksne. DOC og TON verdier målt i testvannet fra utlekkingsforsøkene, som indikerer 

generelt utlekkingsnivå fra rørene, ble også tatt med i risikovurderingen. 

Resultater og konklusjon 

Antall utlekkingsprodukter identifisert ved GC-MS, som lakk ut fra PEX-rørene, varierte fra to 

kjemikalier til 27. Litt overraskende ble det ikke funnet noen sammenheng mellom produksjonsmetode 

for rørene og utlekkingsprodukter. Identifiserte utlekkingsprodukter som det finnes referansestoffer for og 

som det derfor har vært mulig å kvantifisere er gitt i tabell 2. I tillegg ble det påvist en rekke uidentifiserte 

utlekkingsprodukter som fremkom i GC-MS kromatogrammene, sannsynligvis ulike oksygenater, men 

konsentrasjonen av disse utgjorde kun en liten andel sammenliknet med de kjente komponentene. 

Tabell 2: A selection of identified leakage products from the analysed PEX pipes. 

2-methylpropene 

2-methyl-2-propanol 

5-methyl-2-hexanone 

2,6-DTBP (2,6-di-tert-butyl phenol) 

2,6-DTBQ (2,6-di-tert-butyl-p-benzoquinone) 

Ethoxy-2-methylpropane 

DTBP-peroxide 

1,3-DTBB (1,3-di-tert-butyl benzene) 

2,4-DTBP (2,4-di-tert-butyl phenol 

MTBE (Metyl-tert-butyl ether) 

2,4 di-tert-butyl-fenol og metyl-tert-butyl-eter (MTBE) var to av de vanligst forekommende stoffene som 

ble påvist i vannet i utlekkingsforsøkene. Ett av stoffene som ble påvist å lekke ut fra alle de testede PEXrørene 

var 2,6-di-tert-butyl-p-benzoquinon (2,6-DTBQ), i konsentrasjoner mellom 0,1 og 3,0 mikrogra/l. 

Totalt sett var nivåene av de lett flyktige organiske forbundelsene som lekket ut fra nye PEX-rør, generelt 

lave, og nivået ble ytterligere redusert når rørene hadde vært i bruk en stund. 

I tre typer av nye rør ble MTBE påvist i høyere konsentrasjoner enn de grenseverdiene som er anbefalt for 

lukt og smak på drikkevann av amerikanske myndigheter (USEPA), men verdiene ble redusert til under 

denne grenseverdien etter at rørene hadde vært i bruk en stund. 

Risikovurderingen, basert på den informasjonen som foreligger om de aktuelle utlekkingsstoffene som det 

var mulig å kvantifisere, konkluderte med at det ikke er noen helsefare forbundet med å drikke vann fra 

PEX-rør, selv om vannet hadde stått i kontakt med rørene over lengre tid (opptil 72 timer). 

Det testede polybutenrøret, som av enkelte er foreslått som et alternativ til PEX-rør, viste ikke utlekking 

av de stoffene som vi kunne kvantifisere, med unntak en svært høy verdi av 2,4-di-tert-butyl-fenol, på 


1400 g/m 2 indre røroverflate. Noen få typer PEX-rør kan imidlertid gi langvarig uønsket lukt og smak 

på drikkevannet hvis vannet blir stående i rørene over lengre tid. Selv om lukt og smak på vannet stort 

sett forsvinner etter en tids bruk av PEX-rørene, hadde to av rørtypene fortsatt sjenerende lukt og smak på 

vannet etter ett års drift. 

Referanser 

Anselme, C., Bruchet, A., Mallevialle, J. and Fiessinger, F. 1986. Influence of polyethylene pipes on tastes and 

odours of supplied water. Proceeding of the Annual Conference of the American Water Works Association, p. 

1337-1350. 

Brocca, D., Arvin, E. and Mosbæk, H. 2000. Migration of organic additives from polyethylene pipelines into drinking 

water. In: 1st World Water Congress of the International Water Association, Paris, 3-7 July, 2000. CD-ROM, 

AGHTM, Paris. 

Brocca, D. Arvin, E. and Mosbæk, H. 2002. Identification of organic compounds migrating 

form polyethylene pipelines into drinking water.Water Res. 36: 3675-3680. 

Denberg, M., Arvin, E. and Hassager, O. 2007. Modelling of the release of organic compounds from polyethylene 

pipes to water. J. Water Supply Res. T. ••AQUA 56 (6-7): 435-443. 

Denberg, M., Mosbæk, H., Hassager, O. and Arvin, E. 2009. Determination of concentration profile and homogeneity 

of antioxidants and degradation products in a cross-linked polyethylene type A (PEXa) pipe. Polym. Test. 28: 

378-385. 

EN 1622 Water analysis. Determination of the threshold odour number (TON) and threshold flavour number (TFN), 

October 1997. 

EN 1420-1. Influence of organic materials on water intended for human consumption, Determination of odour and 

flavour assessment of water in piping systems. Part 1: Test method. CEN/TC164/WG3, 1999) 

European Commission 2002 Commission Directive of 6 August 2002 relating to plastic materials and articles 

intended to come into contact with foodstuffs (2002/72/EEC). Available from: URL: http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2002:220:0018:0058:EN:PDF. 

European Commission 2005 Synoptic document. Provisional list of monomers and additives notified to European 

Commission as substances which may be used in the manufacture of plastics or coatings intended to come into 

contact with foodstuffs (updated to June 2005), SANCO D3/AS D(2005). Available from: URL: 

http://www.contactalimentaire.com/fileadmin/ImageFichier_Archive/contact_alimentaire/Fichiers_Documents/Avis_ 

de_AESA/synoptic_doc_en_-_version_June_2005.pdf. 

European standard EN 12873-1 2003. Influence of materials on water intended for human consumption ••Influence 

due to migration ••Part 1: Test method for non-metallic and non-cementitious factory made products. 

Gätcher, R. and Müller, H. 1990. Plastic additives handbook. Munich: Hanser. 

Hem. L. and Skjevrak, I. 2002. Potential water quality deterioration of drinking water caused by leakage of organic 

compounds from materials in contact with water. Presentation at NODIG Conference and Exhibition, 

Copenhagen. 

Kerr, C.J., Osborn, K.S., Roboson, G.D. and Handley, P.S. 1999. The relationship between pipe material and biofilm 

formation in a laboratory model system. J.Appl. Mocrobiol. 85: 29-38. 

Lund,V., Anderson-Glenna, M., Skjevrak, I. And Steffensen, I-L. 2011. Long-term study of volatile organic 

compounds from cross-linked polyethylene (PEX) pipes and effects on drinking water quality. J.Water and 

Health 9 (3): 483-497. 

Rogers, J., Dowsett, A.B., Dennis, P.J., Lee, J.V. and Keevil, C.W. 1994. Influence of Temperature and Plumbing 

Material Selection on Biofilm Formation and Growth of Legionella pneumophila in a Model Potable Water 

System Containing Complex Microbial Flora. Appl. Environ. Microbiol. 60 (5): 1585-1592. 

Skjevrak, I. 1998. Drinking water off-flavours ••can we identify their chemical constituents? Vatten 54: 209-212.(In 

Norwegian, English abstract). 

Skjevrak, I., Due, A., Gjerstad, K.O. & Herikstad, H. 2003. Volatile organic components migrating from plastic pipes 

(HDPE, PEX and PVC) into drinking water. Water Res. 37: 1912-1920. 

Skjevrak, I., Lund, V., Ormerod, K. & Herikstad, H. 2005. Volatile organic compounds in natural biofilm in 

polyethylene pipes supplied with lake water and treated water from the distribution network. Water Res. 39: 

4133-4141. 

Umweltbundesamt, Germany 2009 Guidelines for organic materials in contact with drinking water. Available from: 

URL: http://www.umweltbundesamt.de/wasser-e/themen/drinking-water/distribution.htm. 

US EPA 1997 Drinking Water Advisory: Consumer Acceptability Advice and Health Effects Analysis on Methyl 

Tertiary-Butyl Ether (MtBE). EPA-822-F-97-009. Available from: URL: 

http://www.epa.gov/waterscience/criteria/drinking/mtbe.pdf. 

Van der Kooij, D., Vrouwenvelder, J.S. & Veenendaal, H.R. 2003. Effect of pipe material on biofilm formation and 

growth of Legionella in an experimental plumbing system (in dutch). KIWA report KWR 02.090. 


Identity and biodegradability of organic compounds migrating 

from PEX pipes used in water installations in buildings 

Erik Arvin, Hans-Jørgen Albrechtsen*, Charlotte B. Corfitzen, Zuzana Jelinková, Hans- 

Christian Lützhøft, Mikael E. Olsson, Sune T. Ryssel, & Christopher K. Waul. 

Technical University of Denmark. DTU Environment. Miljøvej 1, 2800 Kgs. Lyngby. Denmark. 

* Corresponding author, hana@env.dtu.dk. 

Abstract. Migration of organic compounds from PEX pipes used in water installations in buildings was 

investigated by batch set ups. Several compounds were identified and quantified. The organic compounds 

released to the water phase could support microbial growth and a few of the identified compounds 

decreased in concentration while the microbial number increased. 

Introduction 

Cross linked polyethylene (PEX) pipes are widely used in water installations in buildings due to the high 

flexibility and durability of the material. However, a range of organic compounds migrate from the 

polymers to the water phase (e.g. Brocca et al. (2002), Denberg, (2009), Denberg, et al. (2007; 2009), 

Jelínková (2011)). Many of such polymer materials in contact with drinking water lead to biofilm 

formation on the inner side of the pipes and to bacterial growth in the water phase (Kooij, et al. (2003, 

2006). This may be because the polymers offer a good surface for bacteria to grow on, but the released 

organic compounds may also be substrate for microorganisms in the distribution system (Corfitzen et al. 

2002). So far little information is available on the degradability of specific compounds released from the 

polymer pipes. Therefore, the purpose of our research was to identify and quantify the organic 

compounds which were released from PEX pipes and to determine the microbial growth potential of these 

compounds. 

Materials and methods 

Migration of specific organic compounds from the PEX pipes to the water were partly identified and 

quantified in batch tests. The investigated pipe material was a commercially available Tigris Pex-One 

(Wawin), which is VA approved for household installation for hot and cold water. The pipe was 40 m 

long, (inner diameter: 10 mm, outer diameter: 15 mm). The pipe was winded up and placed in a barrel 

and flushed with MilliQ water for 2 minutes before filling with sterile filtered (0.22 µm) MilliQ water 

(Figure 1). The water was in contact with the pipe for 3 days at 37ºC (Ryssel, 2011). 

A range of compounds were analyzed for using a newly developed head space solid phase 

microextraction gas chromatography mass spectrometry analytical method (HS-SPME-GC-MS). The 

principle of the method is that the water sample (10 mL) is first acidified to pH 2-3 in a 20-mL vial. An 

internal standard (n-pentylphenol) is then added and the head space is extracted by a 

polydimethylsiloxane/divinylbenzene (PDMS/DVB) solid phase micro extraction (SPME) fiber. The fiber 

is analyzed by gas chromatography with a Zebron ZB-5 HT column. The compounds are detected by 

mass spectrometry (MS) in selected ion monitoring (SIM) mode. Samples collected in the field are stored 

cold, and analyzed on arrival to the laboratory. Limit of detection for the selected compounds was less 

than 0.5 µg/L and limit of quantification was 1.5 µg/L. At the level of quantification the precision was 

less that than 20% and the accuracy was less than 30% (Holten Lützhøft et al., 2012). 

The release of non-volatile total organic carbon (NVOC) was also measured in the batch tests. 

To determine the bioavailable fraction of the organic compounds released from PEX, samples of the 

water which have been in contact with the pipe for 3-days were added inorganic nutrient and trace metals, 


Figure 1. The set-up for investigation of migration of organic compounds from a PEX pipe. 

and were inoculated with naturally occurring bacteria from tap water (1% added). The bacterial growth 

was monitored by plate counting on R2A and by measuring ATP. 


The migration tests identified 2,6-di-tert-butyl-p-benzoquinone (CAS # 719-22-2), 2,4-di-tert-butylphenol 

(CAS# 96-76-4) and 3,5-di-tert-butyl-4-hydroxybenzaldehyde (CAS# 1620-98-0) as typical aromatic 

compounds released from the PEX pipes. After a contact time of 3 days at 37ºC, the concentrations of 

these specific compounds were in the range of 0.6-6 µg/L for fairly new pipes (used a few months). 

Additionally, five/six other compounds were observed under the LOD, not to mention the range of 

compounds not identified after the batch test experiments. 

The identified compounds are probably degradation products from antioxidants added to the polymer 

material. 

After a contact time of 1 day the concentrations of released NVOC were 100; and after 3 days it was 422 

µg/L for fairly new pipes. The aromatic compounds released only constituted a minor fraction of the 

NVOC, in the order of 1%. The rest are probably unidentified polymer compounds. 

The biomass growth and the removal of NVOC were analyzed simultaneously. The heterotrophic plate 

count (HPCR2A, 14 d, 20ºC) peaked at a level of 6•10 5 CFU/mL as the NVOC decreased from 422 µg /L 

to a low steady state level (ca. 50 µg/L). The biodegradability of the individual aromatic compounds 

added as pure compounds was also determined using the naturally occurring bacteria from tap water as 

inoculums. Some of the compounds were biodegradable, others were not. Generally, a significant fraction 

of the aromatic compounds could be detected after 30 days of biodegradation. 


This study is probably the first that combines release of organic compounds from a polyethylene pipe 

material and subsequent determination of the biodegradability of both unspecific NVOC and specific 

antioxidant-related aromatic compounds. This information is important when evaluating the impact of 

PEX pipes on the chemical and biological water quality in installations in buildings. 

References 

Brocca, D., Arvin, E., Mosbæk, H., (2002), Identification of organic compounds migrating from polyethylene 

pipelines into drinking water. Wat. Res., 36, 3675-3680 

Denberg, M., (2009). Release of organic compounds from polymer pipes used in drinking water distribution. PhD 

thesis. Technical University of Denmark (DTU). 

Denberg, M., Arvin, E., Hassager, O., (2007). Modeling of the release of organic compounds from polyethylene pipes 

to water. J. Water Supply: Research and Technology - AQUA, 56(6-7), 435-443. 

Denberg, M. Mosbæk, H., Hassager, O., Arvin, E., (2009). Determination of the concentration profile and 

homogeneity of antioxidants and degradation products in a cross-linked polyeth-ylene type A (PEXa) pipe. 

Polymer Testing, 28(4), 378-385. 

Holten Lützhøft HC, Waul CK, Andersen HR, Seredynska-Sobecka B, Mosbæk H, Christensen N, Olsson M, Arvin 

E. (2012). HS-SPME-GC-MS analysis of antioxidant degradation products migrating to drinking water from PE 

materials and PEX pipes. Int. J.Env. Analytical Chemistry. In review. 

Jelínková, Z. (2011). Investigation of antioxidant degradation products from PE and PP drinking water bottles and 

PEX pipes into drinking water: Analysis and quantification. M.Sc. thesis. Technical University of Denmark 

(DTU). 

Kooij, D. van der, H.-J. Albrechtsen, C.B. Corfitzen, J. Ashworth, I. Parry, F. Enkiri, B. Hambsch, C. Hametner, R. 

Kloiber, H.R. Veenendaal, D. Verhamme, E.J. Hoekstra. (2003). Assessment of the microbial growth support 

potential of products in contact with drinking water. CPDW project. Development of a harmonized test to be used 

in the European Acceptance Scheme concerning CPDW. (Construction Products in contact with Drinking Water). 

European Commission. EUR 20832 EN. 

Kooij, D. van der, P.K. Baggelaar, H.R. Veenendaal, L. Moulin, C.B. Corfitzen, H-J Albrechtsen, D. Holt & B. 

Hambsch, (2006). Standardising the Biomass Production Potential method for determining the enhancement of 

microbial growth of Construction Products in contact with Drinking Water - Inter-laboratory testing. European 

Commission. Grant Agreement nbr. SI2.403889. 

Ryssel, S.T. (2011). Afgivelse og bionedbrydning af organiske stoffer fra PEX-rør..B.Sc.thesis. Technical University 

of Denmark (DTU). 

Corfitzen, C.B., H.-J. Albrechtsen,, E. Arvin, C. Jørgensen, & R. Boe-Hansen, (2002). Afgivelse af organisk stof fra 

polymere materialer - mikrobiel vækst (Release of organic compounds from polymers - microbial growth, in 

Danish). Miljøstyrelsen, København. Miljøprojekt, 718. 


Sektionering i Hvidovre Forsyning – Planlægning, udførelse og 

overvågning 

Lars Isager Hedegaard*, Gitte Marlene Jansen **, Michaela Bloch Eiris *** 

* Hvidovre Forsyning A/S, Bibliotekvej 52, 2650 Hvidovre, lars.isager.hedegaard@hvidovreforsyning.dk 

** ALECTIA A/S, Teknikerbyen 34, Virum, gmj@alectia.com 

*** ALECTIA A/S, Teknikerbyen 34, Virum, mbei@alectia.com 

Abstract in English. 

Hvidovre Forsyning has as their stated objective to minimize Non-Revenue Water (NRW) based on the 

fact that in Denmark a water charge has been imposed on water supplies when NRW exceeds 10 per cent 

of the pumped volume of water. Furthermore, Hvidovre Forsyning has as their stated objective to control, 

monitor and survey the quality of water at key locations in the distribution network and secure that each 

source of supply provides clearly defined areas. Based on this Hvidovre Forsyning divided the distribution 

network in 15 sections. The sectioning of the water distribution system minimizes and controls any 

possible spreading of pollution in an emergency situation and at the same time the sectioning of the 

system allows for the option to survey and take action against NRW. In planning of the sectioning targets 

such as security of supply, separation of supply sources, types of consumption (industries, institutions, 

households, etc) and minimizing, NRW forms the basis of the physical delimitation. The sectioning is 

planned in such a way that for example industrial areas are isolated in separate areas and the 

consumption in each section allows for registration of NRW down to 2.5-5 m 3 /h. 

After planning the sectioning Hvidovre Forsyning has established the sections physically during a period of 

three years. Establishing the sections includes temporary block off of the sections (closure of valves) and 

carrying out pressure measurements (also called 0-pressure measurements) to verify that all sections 

have been established. After having made sure that the sections are functioning properly, the sections are 

permanently established by blinding off the pipes that cross the section boundaries. 

Each section is supplied through one or two measure points and additional entrances are pointed out. In 

connection with the measure point a check valve is installed. By doing this it is secured that the water 

which flows into the section cannot flow back to the water distribution system and cause pollution arisen in 

the section. In the measure points parameters as pressure, flow and quality of the water (temperature and 

test cock) are surveyed by a SCADA-system (Supervisory Control And Data Acquisition). 

Based on the SCADA-system data recorded in the measure points, Hvidovre Forsyning has a web-based 

tool that creates an overview of the level for NRW. This tool gives a geographical overview of the 

sectioning and alarms in case the consumption during night-time exceeds the set levels of alarm. The 

levels of alarm regarding NRW are set based on modeling, and are verified by each section being 

examined by leak detecting immediately after the establishment. Besides the option of prompt reaction in 

case of immediate leakages, the surveillance program allows for long-term planning of the leak detection 

effort. By using key figures regarding the level of NRW in each section, the sections can be compared. The 

key figures include analyses from NRW/km pipeline in the section as well as the costs of each section by 

leak detection. On the basis of these data a cost benefit analysis is carried out so that Hvidovre Forsyning 

can focus their leak detection on the most profitable sections. 

The result of the sectioning is that Hvidovre Forsyning knows which sections are supplied from which 

sources and that any pollution incident quickly and efficiently can be identified to a defined area. Besides, 

Hvidovre Forsyning has a tool which creates an overview of NRW and thus time can be saved during 

operation as Hvidovre Forsyning can take action directly against increased NRW. 


Abstract in Danish. 

Hvidovre Forsyning har som målsætning at minimere Non-revenue water (NRW) bl.a. med baggrund i, at 

der i Danmark er pålagt forsyningerne en vandafgift når NRW overstiger 10 % af den udpumpede 

vandmænge. Desuden har Hvidovre Forsyning også en målsætning om at kontrollere og overvåge 

vandkvaliteten på centrale steder i distributionsnettet og sikre, at hver forsyningskilde forsyner klart 

afgrænsede områder. Med baggrund i dette har Hvidovre Forsyning opdelt distributionsnettet i 15 

sektioner. Sektioneringen af ledningsnettet minimerer og kontrollerer en evt. forureningsspredelse i en 

nødsituation og giver mulighed for at overvåge og sætte ind mod NRW. I planlægningen af sektioneringen 

er det målsætninger om forsyningssikkerhed, kildeadskillelse, forbrugstyper (industri, institutioner, 

husholdning mm.) og NRW der danner grundlag for den fysiske afgrænsning. Sektionsinddelingen er 

således planlagt så eksempelvis industriområder inddeles i separate områder og så forbruget i hver 

sektion muliggør registrering af NRW ned til 2,5-5 m 3 /h. 

Efter planlægningen af sektioneringen har Hvidovre Forsyning etableret sektionerne fysisk i løbet af en tre 

årsperiode. Heri indgår midlertidig aflukning af sektioner (ventillukninger) og udførelse af trykmålinger 

(også kaldet 0-tryksmålinger) for at sikre, at sektionerne er helt aflukkede. Når det er sikret, at sektionerne 

fungere efter hensigten, etableres sektionerne permanent ved at afproppe de ledninger, der krydser 

sektionsgrænser. 

Hver sektion forsynes gennem én eller to målerbrønde, og der udpeges eventuelt reserveindgange. I 

forbindelse med målerbrønden etableres kontraventil. Hermed sikres, at det vand, der løber ind i 

sektionen, ikke kan løbe tilbage i ledningsnettet og sprede en eventuel forurening, der er sket inde i 

sektionen. I målerbrøndene overvåges tryk, flow og vandkvalitet (temperatur og prøvehane), via SRO 

anlægget. 

Med udgangspunkt i SRO data fra målerbrøndene har Hvidovre Forsyning et web baseret værktøj, der 

sikrer overblik over niveauet for NRW. Værktøjet giver geografisk overblik over sektioneringen og alarmer, 

hvis nattimeforbruget overskrider de fastsatte alarmniveauer. Alarmniveauet for NRW fastsættes ud fra 

modelberegninger og verificeres ved, at hver sektion lækagedetekteres umiddelbart efter etableringen. 

Overvågningsprogrammet giver udover mulighed for reagerer hurtigt på akutte lækagehændelser desuden 

grundlag for langsigtet planlægning af lækagesøgningsindsatsen. På baggrund af nøgletal for niveauet af 

NRW i de enkelte sektioner kan sektionerne sammenlignes. Nøgletallene omfatter bl.a. analyser af 

NRW/km ledning i sektionen samt hvad det koster at lækagesøge de enkelte sektioner. Med baggrund i 

disse data udføres en cost benefit analyse så forsyningen kan målrette lækagesøgningen mod de 

sektioner, hvor der fås mest for pengene. 

Resultatet af sektioneringen i Hvidovre Forsyning er, at forsyningen har styr på, hvilke sektioner der 

forsynes fra hvilke forsyningskilder og en eventuel forureningshændelse hurtigt og effektivt kan indkredses 

til et afgrænset område. Desuden har Hvidovre Forsyning et værktøj, der giver overblik over NRW og 

dermed kan der spares tid i driften, idet der målrettet kan sættes ind mod forhøjet NRW. 

Planlægning af sektionering 

I følge dansk lovgivning (Vandafgiftsloven) skal vandforsyninger betale vandafgift til staten for den del 

af vandtabet (forskellen mellem udpumpet og afregnet vandmængde) der ligger over 10 % 

/Vandafgiftloven/. Denne afgift har påvirket de danske vandforsyningers bevidsthed til at holde Nonrevenue 

water (NRW) i ledningsnettet på et minimum. 

Flere faktorer spiller ind når NRW skal holdes nede. Disse faktorer omfatter ledningsnettets tilstand, 

trykforholdene, typen af forbrugere, ledningsnettes udstrækning samt vandforsyningens indsats for at 

opspore lækager. Sektionering af ledningsnettet er blot en blandt mange metoder til at opspore og sætte 

ind imod lækager i ledningsnettet. En stadig stigende andel af de danske vandforsyninger har dog siden 

indførslen af vandafgiften i 1994 brugt sektionering som et led i intelligent overvågning af NRW. 

Hvidovre Forsyning distribuerer vand gennem 210 km ledningsnet hovedsageligt i bymæssig bebyggelse. 

NRW i Hvidovre Forsyning har generelt set været faldende i perioden fra 1985 frem til 2010 (figur 1). I 


2011 var NRW niveauet ca. 7 %, hvilket er under landsgennemsnittet i Danmark som i 2011 var ca. 9 % 

/DANVA, (2011)/. 

Figur 1 Udvikling i NRW i Hvidovre Forsyning. /Hvidovre Forsyning (2010)/. Værdier for 2004 og 2005 er 

taget ud, idet der for disse år var målerfejl ved indpumpningen fra Købemhavns Energi. 

Hvidovre Forsyning besluttede i 2009, at få udarbejdet en udbygnings og renoveringsplan i det følgende 

benævnt UR-Plan. Et centralt element i denne plan var at gennemfører en sektionering af ledningsnettet. 

Der var flere incitamenter til at Hvidovre Forsyning på dette tidspunkt valgte at gennemfører en 

sektionering af ledningsnettet. Man ønskede dels at nedbringe og overvåge NRW og dels at sikre sig mod 

spredning af en eventuel forurening i ledningsnettet. Yderligere var det målet at sikre en ensartet 

vandkvalitet, hvilket er særligt vigtigt for de mange industrivirksomheder, som Hvidovre Forsyning har 

som kunder. En ensartet vandkvalitet har netop haft stor betydning i planlægningen af sektioneringen, idet 

vandet indenfor Hvidovre Forsyning består af en blanding af vand fra Hvidovre Vandværk, og en række 

indpumpninger fra KE (Københavns Energi). Forsyningen fra KE sker via fem stationer forsynet fra hhv. 

Regnemark og Thorsbro vandværk. 

Med udgangspunkt i overstående har det helt centrale i planlægningen af sektioneringen været at kunne 

adskille forsyningskilderne i daglig drift således, at hver sektion kun forsynes fra en forsyningskilde. 

Dermed forsyner hver enkelt kilde veldefinerede områder, og der skabes kontrol over forsyningen i en 

forureningssituation, og risikoen for en eventuel forureningsspredning reduceres. Ligeledes var det 

centralt at sektionerne havde en størrelse og sammensætning af forbrugstyper, der gjorde det muligt at 

måle NRW i størrelsesorden 2,5-5 m 3 /h. Der blev i planlægningen lagt vægt på at adskille forbrugstyper 

med meget varierende forbrugsmønster (industri) fra de meget systematiske forbrugsmønstre 

(husholdninger). Særligt i sektioner med betydeligt husholdningsforbrug er der gode muligheder for at 

detektere NRW, idet forbrugsmønsteret her som nævnt er meget systematisk, og nattimeforbruget vil 

derfor være forholdsvis konstant. 

I figur 2 ses den planlagte sektionering i Hvidovre Forsyning. 


Figur 2 Oversigt over sektionering i Hvidovre Forsyning. 

Figuren viser at ledningsnettet inddeles i 15 sektioner, og at nettet kategoriseres i tre ledningskategorier 

(transmissionsledninger, distributionsledninger og forsyningsledninger). Transmissionssystemet, 

forbinder vandværk og indpumpningerne fra KE, og forsyner de enkelte sektioner. 

Transmissionsledningerne etableres som udgangspunkt uden tilslutning af stikledninger. 

Sektionerne indeholder distributionsledninger og forsyningsledninger. Distributionsledninger er 

afgørende for distribution af vand internt i den enkelte sektion. De krydser dermed ikke sektionsgrænser, 

men distribuerer vand til forsyningsledningerne, som forsyner forbrugerne. 

Til hver sektion etableres som udgangspunkt to indgange, hvoraf mindst den ene udgøres af en 

målerbrønd mens den anden kan være en reserveindgang (lukket ventil i daglig drift). 

I figur 3 ses sammensætningen af forbrugstyperne indenfor hver sektion. I Hvidovre Forsyning skelnes 

mellem fem forskellige forbrugstyper (enfamiliehus, erhverv, offentlige ejendomme, fritid og 

etageejendomme). 


Figur 3 Oversigt over forbrugstyper for 14 sektioner i Hvidovre Forsyning. 

Af figuren ses, at forbruget i alle sektioner med undtagelse af Avedøre Holme hovedsageligt stammer fra 

enfamiliehuse og etageejendomme, hvilket giver gode muligheder for at overvåge NRW. På Avedøre 

Holme, er forbruget næsten udelukkende erhverv, og dermed meget varierende. Det kan derfor være 

vanskeligt at overvåge NRW i denne sektion, og det kan derfor være nødvendigt at etablere 

fjernaflæsning hos udvalgte forbrugere i dette område. 

Udførelse 

Efter planlægningen af sektioneringen besluttede Hvidovre Forsyning at etablerede de to første sektioner i 

2010, og yderligere fire sektioner i 2011. De resterende sektioner forventes etableret i 2012. Hvidovre 

Forsyning har dermed opnået et fuldt sektioneret ledningsnet indenfor en tre års periode. 

For at kunne realisere dette har man valgt at prioritere de såkaldte strukturelle projekter frem for de 

tilstandsbaserede renoveringsprojekter. Det betyder, at projekter, der er relateret til sektionering 

(målerbrønde, afskæring og omlægning af ledningsforbindelser mm.), opprioriteres i forhold til de 

projekter, der har med ledningernes tilstand at gøre herunder udskiftning af støbejerns ledninger. 

Etableringen af hver enkelt sektion udføres i en række steps. Første step er at etablere en midlertidig 

aflukning af den enkelte sektion. Den midlertidige aflukning udføres ved, at der udpeges en række 

ventiler langs sektionsgrænsen, som aflukkes. Når den midlertidige aflukning er gennemført, udføres en 

såkaldt ”0-tryks måling”, som skal sikre, at den midlertidige aflukning langs sektionsgrænsen lukker tæt 

og at eventuelle ukendte ledningsforbindelser, der krydser sektionsgrænsen, identificeres. Hvis driften af 

den midlertidige sektionering har forløbet tilfredsstillende, kan den permanente aflukning etableres, når 0tryksmålingen 

er gennemført. I den permanente aflukning afproppes/afskæres ledningsforbindelserne, der 

har været aflukket med ventil i den midlertidige sektionering, og der etableres målerbrønde som indgang 

til sektionen. I målerbrøndene etableres flowmåler, trykmåler, temperaturføler, prøvehane til udtag af 

vandprøver og kontraventil. Ved etablering af kontraventil i målerbrønden sikres, at det vand, der løber 

ind i sektionen, ikke kan løbe tilbage i ledningsnettet og sprede en eventuel forurening, der er opstået inde 

i sektionen. I figur 4 ses målerbrønde som er etableret i Hvidovre Forsynings ledningsnet. 


Figur 4 Målerbrønde klar til etablering. 

I figur 5 ses de tiltag, der skulle gennemføres for at etablere de to sektioner Hvidovre Nordøst og 

Hvidovre Nordvest. Figuren viser, at der skal udføres en række aflukninger betegnet med A1-A7 og 

reserveindgange R1 og R2, samt målerbrønd MB.NØ. Det fremgår også, at der i forbindelse med 

sektioneringen er en række flaskehalse som bør udbedres. Disse flaskehalse (F1-F4) er identificeret i 

forbindelse med de modelberegninger, der er udført i planlægningen af sektioneringen. 

Figur 5 Oversigt over tiltag I forbindelse med sektionering af sektionerne Hvidovre Nordvest og Hvidovre 

Nordøst. Forkortelserne F1-F4 står for flaskehalse, R1 og R2 er reserveindgange, A1-A7 er aflukninger og 

MB.NØ er målerbrønd. 

Ved etablering af sektioneringen er det vigtigt at inddrage driftspersonalet. Fra første færd har udvalgte 

driftspersoner derfor deltaget aktivt i processen og givet deres bud på tidsforbrug ved etablering af 

permanente afpropninger m.m. Driftspersonerne har endvidere deltaget i besøg hos Vandcenter Syd og 

Svendborg Vand for at drage nytte af deres erfaringer med sektionering. 

Overvågning 

Selvom Hvidovre Forsyning endnu ikke har et fuldt sektioneret ledningsnet, har man allerede haft gode 

driftserfaringer med sektioneringen i de områder, hvor den er etableret. Især er det overvågningen af 

NRW, der er den umiddelbare gevinst ved sektioneringen. Måling af nattimeforbruget i målerbrøndene 

giver en god indikation af, om der er et forøget forbrug indenfor hver sektion. 

Med udgangspunkt i SCADA (Supervisory Control And Data Acquisition) data fra målerbrøndene har 

Hvidovre Forsyning et web baseret værktøj, der sikrer overblik over niveauet for NRW. Værktøjet giver 


geografisk overblik over sektioneringen og alarmer hvis nattimeforbruget overskrider de fastsatte 

alarmniveauer. Alarmniveauet for NRW fastsættes ud fra modelberegninger og verificeres ved, at hver 

sektion lækagedetekteres umiddelbart efter etableringen. Overvågningsprogrammet giver udover 

mulighed for reagerer hurtigt på akutte lækagehændelser desuden grundlag for langsigtet planlægning af 

lækagesøgningsindsatsen. På baggrund af nøgletal for niveauet af NRW i de enkelte sektioner kan 

sektionerne sammenlignes. Nøgletallene omfatter bl.a. analyser af det specifikke lækagetab NRW/km 

ledning i de enkelte sektioner samt, hvad det koster at lækagesøge de enkelte sektioner. Med baggrund i 

disse data udføres en cost benefit analyse så forsyningen kan målrette lækagesøgningen mod de sektioner, 

hvor der fås mest for pengene. 

I figur 6 ses udviklingen i nattimeforbruget sammenholdt med det teoretisk midlede nattimeforbrug for en 

sektion i Hvidovre Forsyning. 

Figur 6 Udvikling i nattimeforbrug (m3/h) i sektion Hvidovre Nordvest. 

Det fremgår af figur 6, at NRW i sektionen formodes at være i størrelsesorden 9 m 3 /h over den viste 

periode på ca. 14 dage. Grafen viser, at hverken det midlede nattimeforbrug (midlet værdi mellem kl. 02 

og 04, baseret på 15 min. værdier) eller minimum nattimeforbruget (det mindste forbrug målt mellem kl. 

02 og 04, baseret på midlet 15 min. værdier) nærmer sig det teoretiske midlede nattimeforbrug (beregnet 

værdi baseret på modelberegning). Da den omtalte sektion hovedsageligt består af forbrugstyperne 

enfamiliehus og etageejendom, ville man forvente at minimum nattimeforbruget ville være nær 0 m 3 /h, i 

hvert tilfælde nogle nætter. Dette er endnu en indikation på, at der kan være lækage i sektionen, og at der 

indenfor nærmeste fremtid bør sættes ind med finlokalisering af NRW i sektionen. 

I figur 7 ses et eksempel fra en sektion, hvor overvågningen indikerer, at der ikke er lækage. Figuren 

viser, at det midlede nattimeforbrug er meget lig det teoretisk beregnede, og at minimum nattimeforbruget 

mange nætter nærmer sig 0 m 3 /h. 


Figur 7 Udvikling I nattimeforbrug (m 3 /h) i sektion Hvidovre Nordøst. 

Sammenfatning 

Hvidovere Forsyning har gennem sektioneringen af ledningsnettet fået opfyldt de målsætninger der blev 

defineret ved opstart af projektet. Inddelingen af ledningsnettet i mindre enheder har betydet, at det er 

muligt at overvåge NRW i ledningsnettet og sætte intelligent ind overfor lækagerne. Desuden er 

overvågningen af nattimeforbruget et godt og enkelt værktøj, som specielt driftspersonalet finder meget 

motiverende i forbindelse med finlokalisering af lækagerne. 

Sektioneringen har desuden betydet, at Hvidovere Forsyning har fået adskilt forsyningskilderne således, 

at en eventuel forurening fra en kilde ikke vil spredes til hele forsyningsnettet, men vil forblive i et 

afgrænset område af ledningsnettet. 

En anden effekt af sektioneringen er, at Hvidovre Forsyning i målerbrøndene ved indgangen til de enkelte 

sektioner måler tryk og flow. Disse målinger har stor værdi for kalibrering og brug af 

ledningsnetmodeller, og vil i fremtiden kunne anvendes i en online model som beregner tryk og flow i 

hele ledningsnettet baseret på online målinger b.la. i de etablerede målerbrønde. 

References 

Vandafgiftsloven. Lov om afgift af ledningsført vand. Lovbekendtgørelse nr. 675 af 13. juli 1994. 

DANVA (2011). Vand i tal, DANVA Benchmarking 2011, s 29. 

Hvidovre Forsyning (2010). Teknisk bilagsrapport indvinding og vandbehandling 2010, s36. 


Relining of water mains and drinking water pipes in buildings 

Pelto-Huikko Aino*, Kaunisto Tuija** 

* WANDER Nordic Water and Materials Institute / Prizztech Ltd., Sinkokatu 11, FI-26100 Rauma, Finland, 

aino.pelto-huikko@wander.fi 

** WANDER Nordic Water and Materials Institute / Prizztech Ltd., Sinkokatu 11, FI-26100 Rauma, Finland, 

tuija.kaunisto@wander.fi 

Abstract. Assessment of conformity of the lining material and carefulness of the work performance is a 

requirement for a safe and long-lasting relining. Thus, in order to assure safety and durability national 

guidance and recommendations concerning work performance are needed as well. 

In Finland, relining is done in pipes with epoxy resin coating and in water mains with cement mortar lining. 

However, at the moment there is no decree-based national acceptance scheme or quality control for these 

lining and coating materials in Finland. For water pipes in buildings, the practices of local building 

inspection authorities and site supervision vary a lot. Relining of water mains is not within the building 

inspection, the decision is made by waterworks itself. 

In Finland, nearly all epoxy resin coatings in use have been stated to be safe to use in contact with 

drinking water by VTT Expert Services Ltd. However, at the moment it is not known whether there are 

harmful substances that might affect human health leaching from these relining materials while in use. In 

addition, there is not enough knowledge on the harmful concentrations to health of all the compounds 

possibly leaching from these materials. The tests concerning the safety of the lining material have not been 

conducted on cement mortar linings. 

Nevertheless, despite the material of the pipes or the relining the users should always remember the 

Finnish recommendation to take all the water for drinking or cooking from the cold water faucet and even 

then to run it cold. 

Independent national research including both pipe and water samples is needed to evaluate the safety and 

durability of relining techniques. 

Introduction 

Renovation of drinking water and sewage pipes is current in many housing companies because of the 

aging of the pipes. Many renovation techniques are used e.g. relining of pipes which is done for drinking 

water networks both in buildings and in waterworks. The relining material for metal pipes in buildings is 

epoxy resin and for steel and cast iron pipes in waterworks it is cement mortar. 

No harmful substances affecting human health can leach out from the materials used in drinking water 

networks. In 2011, WANDER Nordic Water and Materials Institute studied both the situation of relining 

and assuring the safety of lining materials in Finland in a project financed by the Ministry of the 

Environment, the Ministry of Social Affairs and Health, The Finnish Real Estate Federation, the 

Development Trust of the Finnish Water Utilities Association and the Federation of Finnish Financial 

Services. No experimental research was done in the project. The results of the project were published in a 

Finnish report. 

Relining in Finland 

The situation of relining in Finland is somewhat confusing. As for relining the water pipes in buildings 

the official supervision e.g. practices of the building supervision vary locally. There is no harmonized 

recommendation for site supervision either. The Finnish Real Estate Management Federation has 


published a study according to which in the greater Helsinki region the relining of water pipes has 

overtaken a market share of 1 % within the pipe renovations (The Finnish Real Estate Management 

Federation 2011). Networks of waterworks are not within the building inspection. 

There is no independent research done on the durability of the relined pipes. Although the inner lining 

of pipes can be considered as a leakage preventive action, the attitude of the Finnish insurance companies 

towards the relining of water pipes has been almost unanimously unfavourable. (Pelto-Huikko & 

Kaunisto 2012) 

At the moment there is no decree-based national acceptance scheme or quality control for these lining 

and coating materials in Finland. Suitability of the epoxy resin coatings to water pipes is attested now 

with foreign certificates or expert••s opinion of VTT Expert Services. A voluntary certificate of VTT 

Expert Services on relining of water pipes including demands on the properties of organic lining 

materials, the work performance and the quality control has been introduced in 2010. By the end of 2011 

not a single company has carried out this certificate. However, it is noticeable that the assessment of 

suitability this certificate requires for the lining material for drinking water use is not fully extensive in 

every part. 

The legislation concerning water supply systems in Finland 

According to the Drinking Water Directive (Council Directive 98/83/EC) and the Finnish decree on 

drinking water (Parliament of Finland 2000) the substances or the new equipment used in water treatment 

or water supply cannot assign impurities to drinking water to greater amount than necessary to make their 

use possible and they cannot endanger the fulfillment of the quality demands of drinking water stated in 

the decrees. This applies both to the pipes of the waterworks and to the materials of the water supply 

system in buildings. According to the building regulations that apply to water supply systems in buildings 

(Ministry of the Environment 2007) acceptability of the materials and products has to be verified with 

appropriate procedures. However, there are no comprehensive national regulations for product approval 

in drinking water systems in Finland. 

According to the regulation of EU laying down harmonised conditions for the marketing of 

construction products (Regulation (EU) No 305/2011) there will be a mandatory CE marking for 

construction products in 2013 but the preparatory work for the CPDW product approval (Construction 

Products in contact with Drinking Water) for the construction products in contact with drinking water is 

still under preparation. It is also unclear whether the lining materials belong to the CPDW product 

approval. Nevertheless, the CPDW evaluation and test methods associated with the CE marking of 

construction products and most probably adopted in the EU countries can be used to assure the safety of 

the lining materials of water pipes. 

In a building a building permit is needed if the intended work might have an effect on the safety or 

state of health of the inhabitants. The relining of the inner pipes can be considered to require a permit 

assessment of the local building authority because it might have an effect on the safety or state of health 

of the inhabitants. 

Suitability of the lining materials to water mains 

Nearly all studied epoxy resin coatings used in Finland has been tested by VTT Expert Services Ltd. 

Because there is no official demands for the assessment of suitability of the lining materials to drinking 

water in Finland, VTT has used the same test procedures and requirements than in the type approval 

instructions based on the decrees of the Ministry of the Environment concerning the suitability of plastic 

pipes to drinking water use. According to the test results of VTT, no great amounts of harmful substances 

are leaching from the epoxy resin coatings. The tested coatings have been estimated to be suitable for 

cold or cold and warm domestic water pipes. 

However, these evaluations and tests don••t fully correspond with the CPDW approval (Construction 

Products in contact with Drinking Water) product approval procedures associated with the CE marking 

that most probably will be adopted for the construction products in contact with drinking water. These 

procedures include the tests for taste and odour, leaching of harmful substances and material induced 

enhancement of microbial growth on surface for organic materials (plastics, rubbers). 


No corresponding tests have been done for cement mortar linings than for epoxy resin coatings. Raw 

materials for cement mortar are Portland cement, sand and water. According to the companies doing the 

linings no additives are used when the pipes are relined. 

For assessment of suitability of the lining materials a CPDW based type approval is proposed. Raw 

materials of the organic lining materials have to be on the positive lists i.e. toxicological evaluations have 

been made for them. Raw materials of the cement mortar lining materials should be on the positive lists as 

well. Type approval tests mentioned in Table 1 should be done on all lining materials. 

Table 1 The type approval based laboratory tests for the organic and cement based materials 

The test Organic materials Cement based materials 

The influence on the organoleptic 

parameters 

The migration of substances 

in drinking water directive 

TOC 

organic chemicals (the positive 

list) 

GC-MS: 

unknown organic chemicals 

(impurities, reaction products etc.) 

The enhancement of microbial 

growth 

Finland 1) : 

EN 1420-1, SFS 2335 A 

CPDW 2) : 

EN 1420-1, EN 1622 

EN 14944-1 

EN 12783-2 EN 14944-3 

prEN 15768 Must be done if any component 

include organic chemicals 

Biomass Production Potential 

(BPP) - ATP (standard) 

Must be done if any component 

include organic chemicals 

1) In Finland, VTT uses organoleptic test procedure which is based on the long term experience on 

testing plastic pipes. 

2) The standard EN 1420-1 is under revision (year 2011). The problem with this standard is the too 

wide deviation of the results and therefore the aim is to harmonize the method and to improve it 

especially on the evaluation part. 

Although the lining materials would have been stated to be safe according to laboratory tests their 

safety as relining materials depend essentially on carefulness of the work performance. At the moment it 

is not known whether there are harmful substances to human health leaching from the lining materials 

while in use. In addition, there is not enough knowledge on the harmful concentrations to health of all the 

compounds possibly leaching from these materials. 

Based on the present knowledge, the safety risk of the harmful substances to human health possibly 

leaching from the epoxy resin coatings, especially Bisphenol A, cannot be dependably evaluated. 

Bisphenol A is a raw material for polycarbonate plastics and epoxy resin coatings and it can be released 

from products into drinking water as a result of an incomplete polymerization or a decomposition of a 

plastic product. It is suspected that bisphenol A interrupts the hormonal functions in lower concentrations 

than the limit value set by the EFSA. Animal tests have indicated that low concentrations of BPA could 

have an effect on e.g. fertility, reproduction, learning and the immune system. The EFSA has last 

evaluated the safety of BPA in 2011 and stated that there is no need to change the set limit value of 0,05 

mg per kilogram of weight. However, the EFSA will evaluate the safety of BPA again as soon as results 

from the ongoing extensive researches on effects of low concentrations of BPA are available. (EFSA 

2010) 

An assessment of suitability of the relining method is done based on a description of the method and 

results from a model relining work. In the description, all the relevant stages for a successful relining 

work have to be included e.g. preliminary preparations and a cleaning, pieces of equipment used, a 


lining, a curing period, an examination of lining, a rinsing, a pressure test and water samples. Tests of 

suitability have to be done for the model relining work. Possible faults in the lining are examined with a 

visual examination and an optical microscope. The minimum and maximum thickness of the lining is 

measured separately. The build-up of an organic lining is tested with e.g. the adhesive button test. The 

ageing treatment test, the salt spray test and the test on the effect of temperature changes on the build-up 

will be done on the lining. Testing of a cement mortar lining include tests on cracking of the lining layer 

and compression resistance. 

Basis to all is the work performance 

A good outcome in relining both in water mains and in buildings requires careful planning and 

implementation in which professional skill and experience are essential. The relining materials can be 

considered to be suitable for drinking water use only if the lining material is prepared carefully according 

to the instructions of the manufacturer. At this point it is necessary to assure that the mixing ratio and the 

temperature are correct and the curing is complete. Unless adequate carefulness is followed substances 

that are harmful to human health or induce microbial growth might leach in practice from the materials 

that in test conditions were faultless. 

Relining requires a good enough pipeline condition so the pipeline condition assessment of the water 

supply network must be done prior to the decision on a renovation method. 

Before the lining the pipe is drained and dried. The lined pipe has to be cleaned from depositions, rust 

and impurities because the lining will reliably succeed only on clean and dry surfaces. If the cleaning 

cannot be done relining is not the correct renovation method. In buildings the cleaning is done with a 

method similar to sandblasting. The water mains are cleaned with metal pipe cleaner and cleaning 

elements. 

In buildings, a pressure test with compressed air is done after the cleaning. The lining is done on a 

clean and dry surface. The lining equipment and the work methods have to be appropriate in order to have 

a smooth, an even and an adhesive layer in the inner pipes. The lining has to be cured completely to 

achieve its final features. 

The plans of maintenance and condition inspections must be a part of the method description and in 

them must be included a description of any possible limitations in the future network renovations. 

Quality control 

Harmonized acceptance procedures and quality control methods have to be implemented for the 

linings and the lining methods. A customer should require these in the call for bids. Additionally, the 

procedures and methods include requirements on what is expected on the lining method and the quality 

control of the liner i.e. what is followed, measured and documented as well as demands for the content 

and provider of an external quality control. 

Quality of drinking water is assured with water samples taken after the lining and flushing of the 

network. After the flushing water is let to stagnate in the network for a certain time and water sample for 

analysis is taken from all the end points. 

In buildings, a water sample must be collected from a lined pipe in a way that water has stagnated in 

contact with the lining material at least two hours. This stagnation period is based on German directions 

so its suitability to Finland should be evaluated. The amount of water depends on the analysis performed 

and the dimensions of the lined network part. Odour, taste and concentrations of chemicals of the material 

is tested from the water samples. In addition, an overnight stagnated water sample is taken from one tap. 

In water mains the sampling is decided case-specifically. 

Because the time frame of the linings in Finland is not known there should be a demand for a regular 

follow-up of the lined network in the call for bids. 

Further actions 

The relining materials of the drinking water networks should have harmonized acceptance procedures. 

In addition, the need of a person or company based certification is evident. Before these acceptance 

procedures can be implemented the orderer should find out in advance the own quality control of the liner 

and agree on how the success of the lining is studied after the actual work performance. 


The effects to human health of the harmful substances possibly leaching from the epoxy resin coatings, 

especially long-term exposure of low concentrations of bisphenol A should be defined. Hopefully 

additional information on this matter will be given already during 2012 while ECHA is studying the 

effects of bisphenol A to human health and environment according to the REACH decree. However, this 

requires a registration of the chemical to lining use by the manufacturer or importer. 

The lining must give adequately operating life to pipes and the lined pipelines have to be safe during 

the whole life span of the network. The quality of drinking water and to a certain extent the building 

habits of the water networks in Finland differ from those in Central Europe. Thus, studies and tests done 

in the other countries cannot be applied to Finland as such. In order to assess the safety and durability of 

lining materials an impartial national research including both pipe and water samples is needed. 

References 

Council Directive 98/83/EC of 3 November 1998 on the quality of water intended for human consumption. The 

Council of the European Union 

EFSA (Europe Food Safety Authority) (2010). EFSA updates advice on bisphenol A. Press Realease. Available: 

http://www.efsa.europa.eu/en/press/news/cef100930.htm 

EN 1420-1:2000 Influence of organic materials on water intended for human consumption. Determination of odour 

and flavour assessment of water in piping systems. Part 1: Test method 

EN 1622:2006 Water quality. Determination of the threshold odour number (TON) and threshold flavour number 

(TFN) 

EN 12873-2:2005 Influence of materials on water intended for human consumption. Influence due to migration. Part 

2: Test method for non-metallic and non-cementitious site-applied materials 

EN 14944-1:2006 Influence of cementitious products on water intended for human consumption. Test methods. Part 

1: Influence of factory made cementitious products on organoleptic parameters 

14944-3:2008 Influence of cementitious products on water intended for human consumption. Test methods. Part 3: 

Migration of substances from factory-made cementititous products 

The Finnish Real Estate Management Federation (2011). Putkiremonttibarometri 2011. Available (In Finnish): 

http://www.isannointiliitto.fi/attachements/2011-03-15T09-32-0941.pdf 

Ministry of the Environment (2007). D1 Water supply and drainage installations for buildings, Regulations and 

guidelines. The National Building Code of Finland. 

Parliament of Finland (2000). Decree of the Ministry of Social Affairs and Health Relating to the Quality and 

Monitoring of Water Intended for Human Consumption. Finnish Acts of Parliament 461/2000. Finland. 

Pelto-Huikko, A. & Kaunisto, T. (2012) Vesijohtojen saneerauspinnoitus. Vesi-Instituutti WANDER Nordic Water 

and Materials Institute Prizztech Oy Ltd. Report series. 2012. Available (In Finnish): 

http://www.prizz.fi/linkkitiedosto.aspx?taso=2&id=878&sid=671 

prEN 15768 (2011). The GC-MS identification of water lechable organic subtances from materials in contact with 

water intended for human consumption 

Regulation (EU) No 305/2011 of the European Parliament and of the Council of 9 March 2011 laying down 

harmonised conditions for the marketing of construction products and repealing Council Directive 89/106/EEC. 

SFS 2335:1988 Muoviputket. PE-paineputket. Laatuvaatimukset. (In Finnish) 


Sikker vannforsyning i vannledningsnett: 

Tiltak for å opprettholde overtrykk i vannledningsnettet 

Gunnar Mosevoll 

Skien kommune, Bydrift, Henrik Ibsens gate 2, N 3701 Skien, gunnar.mosevoll@skien.kommune.no 

Abstract 

Situations with negative hydraulic pressures in the water distribution network increase the risk for microbial 

pollution of the water. In Norway the awareness of negative pressures has increased the last ten years, 

and in most water supply systems plans and actions against negative pressures are in progress. 

There are many causes to negative pressures in water mains. However, a series of measures to prevent 

negative pressures are available. The choice of preventative measure may vary from network to network 

or from place to place in a network. This paper contains a tool box of such measures. The tool box is 

meant as a supplement to the general recommendations in publications as ”Safe Piped Water” from WHO 

/ IWA (2004). 

Situations that may lead to negative hydraulic pressure: 

● Pipe bursts 

● Supply of water to ordinary firefighting and to fire sprinkler plants 

● Flushing of water mains 

● Failure of power supply to pumping stations 

● Pressure surges caused by pump stop or fast valve closure 

Negative pressures may be prevented by the following measures: 

● Two separate supply mains to each of all distribution areas: 

The second supply main can be in permanent operation, or is put automatically into 

operation when the pressure in the distribution area has fallen too low. 

● Service reservoirs 

● A network of transmission mains with good capacity which connects the distribution areas 

● Renovation of water mains with a high risk for pipe bursts (high leakage flow) 

● Replacement of one single pipeline (large diameter) with several parallel pipelines 

(smaller diameter 

● For new pipes preference is given to pipe materials with low risk for brittle failures 

To keep the leakage loss at a low level, the water flow into each distribution area (district meter area) is 

continuously recorded. The measures intended to prevent negative pressures should be designed to 

maintain the continuous recording of the flow into a district meter area. For small district meter areas with 

dual water supply it may be difficult to satisfy the requirement of continuous flow recording. Similar 

metering problem is usual for the supply to business areas with a low, ordinary water demand and a high 

water demand for firefighting. The paper show several solutions to such problems. 

Many of the preventative measures are described by examples from the city of Skien (50 000 inhabitants). 

Most of the water supply areas in Skien are located in hilly terrain between sea level and 100 m above sea 

level. However, the technical solutions may be suited also for less hilly areas. 

Sammendrag: 

Undertrykk i vannledningsnettet øker faren for hygienisk usikkert drikkevann. I Norge har 

oppmerksomheten på undertrykk i vannledningsnettet økt, og de fleste vannverk gjennomfører nå tiltak 

som reduserer faren for undertrykk. 

Det kan være mange årsaker til undertrykk i vannledninger. Det finnes en rekke, mulig tiltak for å 

forebygge undertrykk på vannledningsnettet. Det eller de mest egnede tiltak vil variere fra sted til sted i 

ledningsnettet. Dette foredraget inneholder en verktøykasse med forebyggende tiltak. Denne 

verktøykassen er ment som praktisk hjelpemiddel for å oppnå forbedringer beskrevet i overordnede 

veiledninger som ”Safe Piped Water” fra WHO (2004). 


Forhold som kan skape undertrykk på ledningsnettet: 

● Ledningsbrudd 

● Brannslokking 

● Hagevatning 

● Spyling av vannledninger 

● Svikt i strømforsyning til pumpestasjon 

● Trykkstøt forårsaket av pumpestopp eller ventilstenging 

Tiltak som kan forebygge undertrykk på ledningsnett: 

● Tosidig forsyning til alle forsyningssoner: 

Fast forsyning eller forsyning som koples inn automatisk ved behov for mer vann 

● Høydebasseng 

● Et overordnet ledningsnett med god kapasitet som binder sammen forsyningssonene. 

● Ved fornyelse av ledninger prioriteres ledninger som kan gi svært høy bruddvannføring 

● Erstatning av én ledning med stor diameter med et nett av ledninger med liten diameter 

● Ved fornyelse av ledninger velges fortrinnsvis rørmateriale med stor styrke mot sprøbrudd 

For kunne holde lekkasjetapet tilstrekkelig lavt, må vannforbruket i de enkelte forsyningssonene kunne 

overvåkes kontinuerlig. Tiltakene som skal forebygge undertrykk, må utformes slik at muligheten for 

kontinuerlig overvåkning av vannforbruket blir opprettholdt. Ved tosidig vannforsyning til små 

forsyningssoner kan det bli vanskelig å tilfredsstille kravet om kontinuerlig overvåkning. Dette gjelder også 

næringsområder med lavt vannforbruk og krav om høy vanntilførsel til brannslokking (inkludert 

sprinkleranlegg). Foredraget viser en rekke løsninger på dette problemet. 

I foredraget beskrives tiltakene med eksempler fra Skien kommune i Norge (vel 50 000 innbyggere). Det 

meste av forsyningsområdet ligger mellom 0 og 100 meter over havet, og hovedledningsnettet har en 

lengde på om lag 500 km. Ledningsnettet har de fleste rørmaterialer, og deler av ledningsnettet er mer 

enn 100 år. Skien har en velegnet topografi for å forebygge trykkløst nett. Flere av de tekniske 

løsningene kan imidlertid brukes av vannverk med en annen topografi i forsyningsområdet. 

1. Bakgrunn 

Det stilles strenge krav til kvaliteten til vannet som leveres til forbrukerne, og vannbehandlingen sørger 

for et vann som tilfredsstiller disse kravene. I de seinere årene har kravet til vannbehandling blitt 

skjerpet. Men vannkvaliteten kan svekkes ut over i ledningsnettet. Det kan være en følge av undertrykk 

på vannledningsnettet. 

Det er en rekke årsaker til undertrykk på vannledningsnettet: 

● Stort trykkfall som skyldes høy vannføring i ledningsnettet 

● Trykkfall på grunn av pumpesvikt 

● Trykkfall på grunn av trykkstøt (pumpestopp, ventilstenging) 

● Vedlikehold på vannledningsnett (reparasjon, rengjøring) 

Undertrykk øker faren for forurenset vann trenger inn i vannledningsnettet: 

● Fra abonnent med manglende sikring mot tilbakestrømning 

● Fra forurenset vann i ledningsgrøfter 

▪ Gjennom hull i ledningsnettet 

▪ Ved ledningsbrudd: På selve bruddstedet. 

En rapport fra Norsk vann i 2005 illustrerer denne faren (Wahl 2005, Tveit og Wahl 2006). 

Spørsmål: 

● Er våre ledningsnett tilpasset faren for undertrykk ? 

Eksempel: I hvilken grad vil vannføringen kunne øke så sterkt at det oppstår undertrykk i deler av 

ledningsnettet ? 

● I hvilken grad er det i fornyelsesplanene for vannledningsnett lagt vekt på faren for undertrykk ? 

I dette foredraget gjennomgås de vanligste årsakene til undertrykk, og det beskrives en rekke tiltak som 

reduserer faren for undertrykk. Disse tiltakene er en del av den ”verktøykasse” som er viktig i arbeidet 

for å kunne opprettholde god vannkvalitet utover i et vannledningsnett. 


2. Trykkfall som skyldes høye vannføringer i fordelingsnettet 

Fordelingsnett for vannforsyning i Norge er i stor grad dimensjonert for brannslokking, dvs. at i 

vannledninger med diameter 100 – 200 mm er vannhastigheten mindre enn 0,05 m/s. Dvs. at trykktapet i 

fordelingsnettet vanligvis er lavt. 

Driftsforstyrrelser og brannlokking øker vannføringen vesentlig, se tabell 1 (eksempler fra 

vannledningsnett med vanntrykk 50 – 70 m vannsøyle). 

Tabell 1 Vannføring fra lekkasjer eller andre, høye vannuttak 

Type lekkasje eller vannuttak 

Vannføring 

(liter/sekund) 

En middels stor lekkasje på en privat stikkledning til en enebolig 0,3 – 0,5 

En stor lekkasje på en privat stikkledning til en enebolig 3 – 5 

Tverrbrudd på en ledning av grått støpejern, diameter 100 mm 8 – 12 

Langsprekk i ledning av grått støpejern, diameter 250 mm 80 – 100 

Langbrudd av rør av asbestsement eller PVC, diameter 150 mm 

(sprekk i hele rørets lengde) 

50 – 80 

Brannslokking (enebolig, rekkehus) 20, 40 

Brannlokking (overrislingsanlegg (sprinkler) i næringsområde) 50 

Spyling, vannhastighet 1,0 m/s, diameter 150 mm 18 

Figur 1 viser et eksempel på vannføringen gjennom et brudd på en fordelingsledning. Dersom bruddet 

hadde skjedd om natten, ville det tatt lengre tid å få stengt av bruddet. Vannføringen er målt på utløpet 

fra et høydebasseng som leverer vann til overføringsledningen i dette området. 

Vannføring (m 3 /time) 

395 

125 

Bruddet 

starter 

Avstengning på 

den ene siden 

Start avstengning på 

den andre siden 

Avstengning fullført 

kl. 1601 kl. 1725 Tid 

Figur 1 Eksempel på vannføring og varighet for et vannledningsbrudd (fordelingsledning). 

Klyve i Skien, 2. mai 2012. Maksimal vannføring ut av bruddet 270 m 3 /time ( 75 l/s) 

Volum på lekkasjevannet: Om lag 300 m 3 . 

Rørmateriale: Asbestsement. Rørdiameter: 150 mm. Sprøtt brudd i hele rørets lengde (4 m). 

Vanlig vanntrykk 6 – 7 bar. Overføringsledningen i dette området har god kapasitet. 


Ved høy vannføring blir det stort trykktap i vannledningsnettet, se eksempler i tabell 2 nedenfor. 

Tabell 2 Eksempel på trykktap i en vannledning. Verdien gjelder for en ledningslengde på 100 m. 

Her er det valgt en absolutt, hydraulisk ruhet på 1 mm. Deler av vannledningsnettet har større 

ruhet enn dette. Men etter hvert som vannledninger av grått støpejern tas ut av drift, vil en 

stadig større del av ledningsnettet få en hydraulisk ruhet på om lag 1 mm. 

Vannføring Trykktap (m vannsøyle) 

Lengde 100 mm Ruhet 1,0 mm 

(liter/sekund) D: 100 mm D: 150 mm 

5 0,8 0,1 

10 3,2 0,4 

20 12,6 1,5 

40 50,3 5,8 

De høyeste vannføringene i tabellen 2 kan gi undertrykk i fordelingsnettet, se prinsippskisse i figur 2. 

Hvis det er lekkasjer på vannledningen, er det fare for innsuging av forurenset vann fra jordmassene 

omkring vannledningen (forutsatt at omfyllingsmassene ikke er godt drenert). Innsuging fra et åpent 

basseng hos en abonnent er også mulig. 

Basseng 

Trykklinje ved: 

Intet vannforbruk 

Vanlig vannforbruk 

Svært høyt vannforbruk 

Figur 2 Eksempel på trykkfall langs en vannledning som forsynes fra et høydebasseng. 

Hvis vannforbruket blir særlig høyt, skaper det undertrykk i høytliggende områder. 

3. Tiltak mot undertrykk 

Undertrykk 

3.1 Oversikt 

Et godt vannledningsnett har innebygget sikkerhet mot undertrykk. Denne sikkerheten skapes av: 

● Inndeling av vannledningsnettet og bruk av høydebasseng 

● Bruk av høydebasseng i forsyningssoner der vannet pumpes 

● Inndeling av ledningsnettet i sløyfer slik at det blir tosidig vannforsyning mot et lekkasjepunkt 

● Trykktap ved selve vannuttaket som begrenser trykkfallet 

● Trykkstøtdemping i pumpestasjoner 


● Forbud mot ventiler kan lukkes raskt 

● Rørbruddventil (forutsatt ventil med et lite omløp som ikke stenges automatisk) 

● Gode driftsrutiner 

● Gode saksbehandlingsrutiner ved godkjenning av sprinkleranlegg for brannslokking 

● Valg av rørmateriale med liten fare for sprøbrudd 

● Systematisk utskifting av ledninger med stor fare for høy bruddvannføring 

Alle disse tiltakene er enkle. Noen tar derfor god sikkerhet mot undertrykk som en selvfølge, men det 

trenger ikke være riktig. I Norge skyldes det en kombinasjon av kostnadene for de aktuelle tiltakene og 

lite konkrete krav. I nasjonal statistikk i Norge brukes fornyelsestakten (antall km ledning fornyet i året) 

som mål for innsatsen på vannledningsnettet. Det føres i dag ingen statistikk for gjennomførte tiltak som 

forbedrer sikkerheten mot undertrykk. 

I det følgende beskrives de enkelte tiltak nærmere. 

3.2 Nærmere beskrivelse av tiltak mot undertrykk 

3.2.1 Inndeling av vannledningsnettet og bruk av høydebasseng 

Vannledningsnettet kan deles inn i (se figur 3): 

● Overføringsledninger (overfører vannet fra vannbehandlingsanlegg til forsyningssonene) 

● Fordelingsledninger (fordeler vannet fra overføringsledningene) 

● Stikkledninger (fra fordelingsledning inn til den enkelte bygning) 

Overføringsledningene kjennetegnes ved: 

● Stor kapasitet 

● Høy driftssikkerhet 

● Vanligvis tilknyttet høydebasseng, som bidrar til å opprettholde et jevnt trykk 

● Ingen abonnenter er direkte tilknyttet overføringsledninger 

Fordelingsledningene kjennetegnes ved: 

● Stor variasjon i kapasiteten 

● Stor variasjon i driftssikkerheten 

● Abonnentene er tilknyttet via stikkledningene. 

Vannbehandlingsanlegg 

Pumpe 

Fordelingsnett 

Overførings- 

ledning 

Høydebasseng 

Figur 3 Fordelingsledningene leverer vann til overføringsledningene. Fordelingsledningene får vannet 

fra overføringsledningene. 

Overføringsledninger med høydebasseng bør ha kapasitet til å forebygge undertrykk i 

fordelingsnettet. 


Fordelingsnettet er sårbart for store trykkfall i overføringsledningene. Anbefalte krav til overføringsledninger 

og høydebasseng: 

● Overføringsledninger: Selv de største vannføringene i fordelingsnettet (ledningsbrudd, 

brannslokking) skal ikke medføre trykkfall med fare for undertrykk. 

● Høydebasseng: Skal ha volum tilstrekkelig for det ekstra vannforbruket til 

ledningsbrudd eller brannslokking. 

Det meste av volumet i høydebassenget er reservevolum. For at 

vannkvaliteten i bassenget ikke skal svekkes vesentlig, må følgende 

krav være oppfylt: 

▪ God kvalitet på innkommende vann 

▪ God omrøring i bassenget (forebygger at noe vann får lang 

oppholdstid) 

● Overføringsledninger: Sikkerheten mot ledningsbrudd må være stor. 

Ledningsmaterialer med stor fare for sprøbrudd bør unngås. 

Strekninger av grått støpejern bør skriftes ut (i 2012 er det 

nesten 50 år siden siste ledning av grått støpejern ble lagt). 

3.2.2 Bruk av høydebasseng der vannet må pumpes 

Figur 4 viser to eksempler på hvordan et høydebasseng kan opprettholde overtrykk i vannledningene: 

A. Høydebassenget ligger så høyt at alle har tilfredsstillende vanntrykk selv om pumpestasjonen svikter 

B. Når pumpestasjonen svikter, faller trykklinjen ned til nivå med vannstanden i høydebassenget. 

Bassenget ligger så høyt at det skaper overrykk i ledningsnettet i pumpesonen. De høyest liggende 

abonnentene får imidlertid for lavt trykk for vanlig bruk. 

Alternativ A er det beste, men i mange tilfeller er det ikke mulig å få bygget et høydebasseng høyere enn 

høyest liggende forbrukere. Også alternativ B forebygger trykkløst nett, og dette alternativet er derfor 

brukbart. 

A. 

B. 

P 

P 

Figur 4 Høydebasseng sørger for å opprettholde overtrykk i vannledningen når pumpestasjonen (P) 

svikter. 

De vannrette, tynne linjene viser trykklinjene for forskjellige situasjoner. 

194 Session 4: Distributionssystem 

Hmin 

Når pumpestasjonen svikter, gir 

høydebassenget trykk nok til vanlig forbruk 

på denne strekningen (vannrett pil) 

Hmin 

Hmin 

Hmin er kravet til trykk 

i fordelingsnettet 

Når pumpestasjonen svikter, sørger 

høydebassenget for at det ikke blir 

undertrykk på denne strekningen 

(vist med vannrett pil)

Hvis det ikke er mulig å få plassert et høydebasseng høyt nok, kan bassenget plasseres på det høyeste 

punktet i forsyningsområdet, se figur 5 (alternativ C): 

C: Høydebassenget er plassert på det høyeste punktet i forsyningsområdet 

Hovedpumpestasjonen (P1) sørger vanligvis for tilstrekkelig vanntrykk. Hver natt fylles bassenget 

gjennom en trykkreduksjonsventil. Om morgenen, samt i andre perioder med høyt vannforbruk, 

bidrar pumpestasjon P2 til forsyningen (tar vann fra bassenget). Dersom forsyningen til pumpestasjon 

P1 svikter, starter P2 og opprettholder tilstrekkelig vanntrykk. 

C. Vanligvis forsyner pumpestasjon P1 det høytliggende området. 

Hver natt åpner trykkreduksjonsventilen TRV og slipper vann inn i høydebassenget. 

Hver morgen, samt i andre perioder med høyt vannforbruk, leverer pumpestasjon P2 

vann fra bassenget til forsyningsområdet. 

Hp1 

P1 

Figur 5 Høydebassenget er plassert på det høyeste punktet i forsyningssonen. 

Vanligvis sørger pumpestasjon P1 for tilstrekkelig vanntrykk. 

Hvis vannforsyningen fra P1 svikter, overtar pumpestasjon P2 forsyningen (leverer vann fra 

høydebassenget. 

De vannrette, tynne linjene viser trykklinjene for forskjellige situasjoner. 

Dette er en prinsippskisse, og høydeforholdene er fortegnet. 

3.2.3 Inndeling av fordelingsnettet i sløyfer 

Forsyningsområde for pumpestasjon P1 

Hr Hp2 

TRV P2 

Deler av fordelingsnettet kan være bygget i gaffelform, se figur 6. Hvis det oppstår et stort ledningsbrudd 

f. eks. mellom punkt C og B, vil vanntrykket kunne falle til 0 mellom lekkasjen og punkt B. Er 

ledningsnettet knyttet sammen med ledning A – B, strømmer imidlertid vannet fra to sider fram til 

lekkasjen. Dette reduserer faren for at vanntrykket skal falle helt ned til 0. Dersom bruddet er et 

tverrbrudd i en ledning av grått støpejern, vil tosidig vannforsyning gjøre det mulig å reparere lekkasjen 

samtidig som det opprettholdes overtrykk på lekkasjen. Fordelingsnett bygget opp av sløyfer gir tosidig 

vannforsyning og reduserer derfor faren for undertrykk. 

For å kunne overvåke lekkasjetapet må fordelingsnettet inndeles i forsyningssoner. For at vannmåleren 

skal kunne måle minimum nattvannføring med god nok nøyaktighet, har de fleste forsyningssoner bare én 

tilførselsledning. Kun én forsyningsledning gir for dårlig driftssikkerhet. Figur 7 viser en løsning som 

gir god nok målenøyaktighet og tosidig vannforsyning. Dersom vannforbruket øker sterkt, og trykket 

faller, åpner en trykkreduksjonsventil på en ledning som vanligvis er stengt. Dette skjer imidlertid så 

sjelden at det ikke har noen praktisk betydning for overvåkning av lekkasjetapet. 


Plan: A 

Oppriss mellom C og B: 

Dersom ledningsnettet er 

knyttet sammen med 

ledning A - B , faller vanntrykket 

fra begge sider fram 

til lekkasjepunktet 

Figur 6 Med ledningsnett utformet som sløyfer, blir det lettere å opprettholde overtrykk ved store 

lekkasjer (vannledningsbrudd). Ledningsnett bør derfor lukkes ved hjelp av ledninger som A - B. 

Ledningsnett i sløyfer forenkler også reparasjoner på ledningsnettet- 

Vannmåler 

C 

Overføringsledning 

Lekkasje 

Trykklinjer 

C B 

Figur 7 Vanligvis forsynes dette området gjennom ledningen med vannmåleren. Dermed kan lekkasje- 

tapet overvåkes automatisk. 

Øker vannforbruket så mye at trykket synker (ledningsbrudd eller brannslokking), 

åpner trykkreduksjonsventilen (TRV) automatisk og sørger for tilstrekkelig forsyning. 

Dersom det ikke er så stor forskjell i trykket mellom to trykksoner, kan de settes en tilbakeslagsventil på 

en ledning mellom de to sonene. Ventilen hindrer at det strømmer vann fra sonen med høyt trykk (sone 

Høy) til sonen med lavt trykk (sone Lav), og denne ledningen er derfor vanligvis stengt. Dersom 

vannforbruket i sone Høy øker sterkt og trykket faller, vil tilbakeslagsventilen åpne og sone Lav vil 

levere vann til sone Høy. 

196 Session 4: Distributionssystem 

TRV 

Fordelingsnett 

B

3.2.4 Vann til brannslokking og sikring mot undertrykk 

Vi kan dele vannforsyningen til brannslokking i to: 

● Vanlig brannslokking (slokking fra brannventiler plassert utendørs) 

● Automatiske overrislingsanlegg (sprinkleranlegg) 

Brannvesenet i Norge bruker gjerne pumpe ved vanlig slokking med vann fra offentlige vannledninger, 

og brannvesenet har da ikke full kontroll med hvor mye vann som tappes til slokking av brannen. Det er 

derfor mulig at det trekkes ut så mye vann at det skaper undertrykk på fordelingsnettet. Dette forbygges 

ved at det i fordelingsnettet brukes brannventiler som alltid skaper et visst trykktap. I Norge brukes i 

fordelingsnettet brannventiler med kule, som vanligvis gir et trykktap på 1,0 – 1,5 bar ved uttak av 

20 liter/sekund. Dette er de fleste steder tilstrekkelig trykktap for å unngå undertrykk på fordelingsnettet. 

Brannventiler med lavt trykktap bør kun brukes ved uttak fra overføringsledninger, der kapasiteten er 

vesentlig større enn brannvesenets behov. 

Vannverket skal godkjenne dimensjoneringsgrunnlaget for automatiske overrislingsanlegg 

(sprinkleranlegg), dvs. at vannverket angir med hvilket vanntrykk dimensjonerende vannføring skal 

kunne leveres ved. Det dimensjonerende vanntrykket og den dimensjonerende vannføringen danner 

grunnlaget for utformingen av overrislingsanlegget. I Norge forekommer det imidlertid at overrislingsanlegg 

likevel bygges slik at vannbehovet er høyere enn den godkjente vannføringen. Slike 

overrislingsanlegg medfører økt fare for undertrykk på ledningsnettet, samtidig som det er fare for at 

anlegget ikke får dekket sitt vannbehov. Det er derfor viktig at vannverket har gode godkjenningsrutiner 

for automatiske overrislingsanlegg. 

3.2.5 Fornyelse av vannledninger og valg av rørmateriale 

godtas en dårligere driftssikkerhet. 

I planene for fornyelse av vannledningsnettet bør sårbarheten mot vannledningsbrudd vises særskilt. 

Disse planene må derfor gi en oversikt over vannledninger med stor fare for store ledningsbrudd. Dette er 

særlig ledninger av: 

● Grått støpejern (hovedsakelig fra tiden før 1965) 

● Asbestsement uten innvendig beskyttelse mot tæring fra vannet 

● uPVC fra 1970-tallet 

Alle disse rørmaterialene gir sprø brudd, og for ledningene av asbestsement og uPVC er det ikke uvanlig 

s hele lengde. 

Plastrør lagt etter 1980 har vesentlig bedre kvalitet enn eldre rør. Det er imidlertid uklart om CENstandardenes 

reduksjon av sikkerhetsfaktoren for uPVC og PE fra henholdsvis 2,5 til 2,0 og fra 1,6 til 

1,25 øker faren for sprøbrudd når rørene nærmer seg sin levetid. Hyppige sprøbrudd kan øke faren for 

sprøbrudd. De fleste norske kommuner kjøper imidlertid ikke rør med de lave sikkerhetsfaktorene; noe 

som trolig øker sikkerheten mot alvorlige sprøbrudd. 

Videre øker vannføringen ved brudd med økende rørdiameter. For ledninger av grått støpejern og 

diameter 100 – 150 mm gir de fleste brudd ikke større lekkasjevannføring enn 8 – 12 liter/sekund, og 

brudd på denne typen rør trenger derfor ikke å medføre stor fare for undertrykk. 


Ved valg rørmateriale for nye vannledninger er det ikke tilstrekkelig å velge rørmaterialer med minst 

100 års levetid. Som nevnt ovenfor bør det også velges rørmaterialer med god sikkerhet mot 

sprøbrudd: 

● Rør av seigt støpejern og stål har god sikkerhet mot sprøbrudd, men slike rør krever en god 

beskyttelse mot korrosjon. 

● Rør av uPVC og PE er ikke utsatt for korrosjon, men faren for sprøbrudd må vurderes særskilt. 

Når disse rørene nærmer seg enden av sin levetid, øker faren for sprøbrudd vesentlig. Det er derfor 

viktig at det velges rørkvaliteter som kjennetegnes med korte sprekker og sakte sprekkvekst. 

4. Konklusjon 

Undertrykk på vannledningsnettet kan svekke vannkvaliteten vesentlig, og systematiske tiltak mot 

undertrykk er derfor viktige. Disse tiltakene kan deles i følgende grupper: 

● Utforming av ledningsnett med pumpestasjoner og høydebasseng 

● Tiltak som begrenser vanlige uttak av vann fra ledningsnettet 

● Fornyelse av ledninger med stor faren for brudd med stor vannføring 

● Valg av rørmaterialer for nye vannledninger (materialer med liten fare for alvorlige sprøbrudd). 

Gjennomføring av slike tiltak bidrar derfor vesentlig for å opprettholde tilfredsstillende vannkvalitet i 

ledningsnettet. 

Referanser 

Aintworth, R. (ed) (2004): Safe Piped Water 

- Managing Microbiological Water Quality in Piped Distribution Systems 

WHO / IWA, 2004 

Wahl, E. (2005). Kartlegging av mulig helserisiko for abonnenter berørt av trykkløs vannledning ved arbeid på 

trykkløst nett. Norsk vann rapport R143/205. 

Tveit, O. A., Wahl, E. (2006). Kartlegging av helserisiko for abonnentene ved trykkløs vannledning, 

Nordiske drikkevannskonferanse, Reykjavik 2006. 


Genomträngning av kemiska markföroreningar till dricksvatten 

i distributionsnätet 

Magnus Bäckström*, Maria Eklund **, Ann-Sofie Wikström*** 

* Vatten & Miljöbyrån AB, Bergvikskurvan 11 C, SE 973 31 Luleå, Sweden, magnus@vmbyran.se 

** Vatten & Miljöbyrån AB, Bergvikskurvan 11 C, SE 973 31 Luleå, Sweden, maria.eklund@vmbyran.se 

*** Vatten & Miljöbyrån AB, Bergvikskurvan 11 C, SE 973 31 Luleå, Sweden, ann-sofie@vmbyran.se 

Abstract. 

Chemical substances in the soil, dissolved in water or in the gas phase, may affect the drinking water but 

confirmed cases with serious consequences are as yet very few. There are incidents of bad taste and 

odour in drinking water when small diameter service pipes are located in moss and swamps or in oilcontaminated 

soil. The risk of penetration of toxic soil contamination by diffusion through the pipe wall or 

seals and gaskets is however a relevant topic for water engineers, for example in connection with 

conversion of former industrial land or construction/reconstruction of filling stations. What safety 

precautions that are reasonable to demand are difficult to prove, because the risk of contamination is 

difficult to assess. 

Previous studies have shown that the penetration of benzene and other organic pollutants may occur 

through gaskets (styrene-butadiene rubber) in water mains of ductile iron. Permeation of organic pollutants 

through plastic pipes including the passage of hydrocarbons through PE and PVC pipes and their seals / 

joints has recently been studied in the United States. These studies show, often by different testing 

methods in laboratory conditions, that permeation may occur in plastic pipes as well as ductile iron pipes 

with different types of gaskets. However, it is very unlikely that permeation is a major threat to public health 

since the typical incident of permeation occurs when water consumption is extremely low and 

concentrations of organic soil contaminant are very high. Thus, permeation is especially a relevant issue 

when designing or operating service lines in contaminated soil. 

Bakgrund och syfte 

Huruvida dricksvatten som transporteras i en ledning kan ta smak av ämnen som finns i 

omkringliggande mark är normalt inte en stor fråga vid projektering och anläggning av vattenledningsnät. 

Det finns dock erfarenheter av att vattenledningar förlagda längre sträckor i moss- och myrmark kan ge 

dålig smak på vattnet, i synnerhet om det rör sig om ändledningar av mindre dimensioner med tidvis 

stillastående vatten. Kemiska ämnen i mark, lösta i vatten eller i gasfas, kan således påverka dricksvattnet 

negativt. 

Enligt Svenskt Vatten är den samlade längden av vattenledningar i Sverige ungefär 70 000 kilometer 

(Malm och Svensson, 2011), privata servisledningar ej medräknat. Det allmänna vattenledningsnätet som 

finns idag har anlagts under ett drygt sekel, huvudsakligen i urban miljö. Den sammanlagda ytan av 

rörvägg som är i kontakt med omgivande mark är således mycket stor. Tidigare och nuvarande hantering 

av farliga ämnen i vårt samhälle innebär en risk för markförorening eller akut spridning av vätskor, 

exempelvis drivmedel eller industriavloppsvatten. 

Risken för genomträngning av toxiska markföroreningar via diffusion genom rörvägg eller 

tätningsringar/packningar aktualiseras regelbundet, även om dokumenterade fall från svenska kommuner 

är få. I samband med städernas förtätning och omvandling dyker frågan upp när verksamheter som 

hanterar giftiga kemiska ämnen, exempelvis bensinmackar, önskar etablera sig i nära anslutning till 

befintliga distributionsledningar för dricksvatten. Frågan kan också dyka upp när ombyggnad eller 

nyexploatering planeras i områden med förorenad mark eller i områden där inkapslat organiskt material 

leder till gasbildning. Ytterligare en situation av mer akut karaktär är när vattenabonnenter hör av sig med 


klagomål på smak och lukt som möjligen kan förklaras av att ämnen från omgivande mark påverkar 

dricksvattnet. 

Föreliggande projekt, med Svenskt Vatten Utveckling som huvudfinansiär, har som syfte att kartlägga 

kunskapsläget avseende risken för genomträngning av kemiska föroreningar till dricksvatten i 

distributionsnätet. Studien fokuserar på kemiska ämnen i mark som är toxiska eller som kan orsaka smak- 

och luktproblem. Mikrobiella föroreningar studerades ej, då förekomst och spridning av dessa antogs 

behandlas inom ramen för andra pågående projekt. 

Huvudsaklig metod har varit litteraturstudier och projektet kommer att slutrapporteras i form av en 

SVU-rapport inom kort. För fullständigare beskrivning av projektets resultat hänvisas till den kommande 

rapporten, framförallt kommer där att ges mer detaljerad beskrivning av genomträngningsprocessen i 

olika typer av material (PE, PVC och tätningsring/Segjärn) utifrån nyligen genomförd forskning. 

Slutrapporten kommer att göras tillgänglig via Svenskt Vattens hemsida. 

Allmänt om genomträngning från mark till dricksvatten 

Föroreningar kan teoretiskt tränga in i dricksvatten från omgivande förorenad mark via exempelvis rör, 

kopplingar, tätningsringar, reservoarer etc som är gjorda i material som medger genomträngning 

(permeation). Problemet är generellt begränsat till ickemetalliska polymeriska material, såsom plast. 

Genomträngning är en fysikalisk-kemisk överföring av massa vilken involverar diffusion av ett ämne 

genom ett poröst fast medium. Genomträngning kan ske av ämnen såväl i gasfas som vattenlöst fas. De 

föroreningar som är av störst intresse i fråga om genomträngning i dricksvattensystem är flyktiga 

kolväten och organiska lösningsmedel. Risken finns både för dricksvattensystem anlagda i den omättade 

och mättade zonen, dvs. både över och under grundvattennivån. 

Materialet i plaströr och tätningsringar består av polymerer d v s långa strängar av sammankopplade 

molekyler. PVC-plast består exempelvis av kedjor av vinylkloridmolekyler. Polymererna ligger tätt 

sammanpackade, men det finns ändå små mikroskopiska hålrum mellan polymerkedjorna. Stora grenade 

eller sfäriska molekyler, exempelvis kolvätekedjor med minst sju kolatomer, har svårt att tränga genom 

materialet eftersom hålrummen är för små. Små molekyler kan däremot via hålrummen vandra genom 

polymermaterialet. En avgörande anledning till att materialen ändå är vattentäta så att inte vatten läcker 

ut, är att vattenmolekylen är polär medan polymermaterialen i allmänhet är opolära. 

Vatten är ett starkt polärt ämne och stöts därför bort från de opolära polymererna som utgör rörväggen 

eller tätningsringen, vilket gör polymermaterialen vattentäta. Däremot kan opolära små molekyler, såsom 

exempelvis bensen, vandra genom polymermaterialen via tillgängliga hålrum. När en dricksvattenledning 

ligger i förorenad mark finns därför risk att opolära förorenande ämnen vandrar från marken eller 

markvattnet genom ledningen och in i dricksvattnet. 

Genomträngning (också benämnt permeation) av externa föroreningar till dricksvatten kan ses som en 

trestegsprocess: sorption - diffusion - desorption. Först vandrar föroreningen från marken eller 

markvattnet till rörets utsida, där det löser sig i rörmaterialet och börjar tränga in (sorption). Därefter 

diffunderar ämnet genom rörets porösa struktur. Slutligen löser sig ämnet och tränger in i dricksvattnet på 

insidan av röret (desorption). 

Ämnens förmåga att tränga genom olika polymermaterial beror på två huvudfaktorer: ämnets löslighet 

i det aktuella materialet och dess diffusionshastighet genom materialet (Cheng 2009). Ämnet 

(föroreningen) som tränger igenom vattenledningens rörvägg kan vara i vätske- eller gasform. Dess 

löslighet beror på hur ämnet interagerar med polymermaterialet, varvid polariteten har stor betydelse. 

Diffusionshastigheten beror på föroreningens molekylstorlek och polymermaterialets egenskaper. Viktiga 

egenskaper är bland annat materialets bulkdensitet (hög täthet innebär liten hålrumsvolym) och dess 

fysiska struktur (kristallin, amorf eller semikristallin struktur). Kristallin struktur innebär att atomerna är 

ordnade i en geometriskt regelbunden struktur. Amorf är motsatsen, atomstrukturen är oordnad, 

polymersträngarna ligger slumpvist kors och tvärs. Ett semikristallint material består av både kristallina 

och amorfa polymerer. 

Genomträngningen av små molekyler genom ett polymermaterial sker alltså genom en trestegsprocess: 

Sorption Diffusion Desorption. 

Sorptionen, d v s hur mycket av det förorenande ämnet som hamnar på utsidan av röret eller 

tätningsringen och kan tränga in per ytenhet beror främst på ämnets koncentration i marken eller 


markvattnet samt fördelningskoefficienten (lösligheten, betecknad S) för ämnet i det aktuella 

polymermaterialet. 

När det förorenande ämnet har fördelat sig över polymermaterialets gränsyta och börjat tränga in vidtar 

diffusionsprocessen, d v s det förorenande ämnets vandring genom polymermaterialet via s k Browns 

molekylrörelse. Den innebär molekylförflyttning som inte drivs av andra krafter än 

koncentrationsskillnader. Koncentrationen av det förorenande ämnet är högst i gränsytan mellan polymer 

och omgivande mark. Diffusionen innebär att ämnets molekyler successivt förflyttas inåt, i riktning mot 

rörets insida, eftersom lägre koncentration råder där. Förflyttningen pågår så länge det råder en 

koncentrationsskillnad mellan utsida och insida. Diffusionen bestäms av den diffusionskoefficient D 

(enhet cm 2 /s) som gäller för den aktuella kombinationen av penetrerande ämne och polymermaterial. 

Desorption kallas processen när det förorenande ämnet vandrar in i dricksvattnet från insidan av röret 

eller tätningsringen, alltså i princip den omvända processen till sorption. När det mottagande mediet är 

identiskt med det exponerade mediet så styrs sorptions- och desorptionsprocesserna av samma 

fördelningskoefficient, förutom i de fall när penetrantmolekylen är starkt bunden i polymeren. 

Flux, förkortad F, defineras som den mängd av det penetrerande ämnet som tränger igenom en viss 

kontaktyta (exponerad yta) per tidsenhet. Fluxen är ett resultat av alla tre processerna sorption - diffusion 

- desorption. Fluxen bestäms av en permeationskoefficient P (enhet cm 2 /s), vilken är en produkt av S*D, 

alltså fördelnings- och diffusionskoefficienterna. Fluxen ges av följande ekvation enligt Cheng (2009): 

F = D*S*(Cm - Cd )/l = P *(Cm - Cd )/l 

F = flux d v s massflöde förorening som tränger genom per ytenhet (µg/cm 2 /d) 

Cm = koncentration av förorenande ämne i markvattnet närmast röret (mg/l) 

Cd = koncentration av förorenande ämne i dricksvattnet (mg/l) 

D = diffusionskoefficient för aktuell kombination förorening och polymermaterial (cm 2 /d) 

S = det förorenande ämnets löslighet (fördelningskoefficient) i polymermaterialet (dimensionslös) 

P = permeationskoefficient för aktuell kombination förorening och polymermaterial (cm 2 /d) 

l = polymermaterialets, d v s rörets/tätningsringens, tjocklek (cm) 

Samma tidsenhet ska användas för F, D och P. Ovan har använts dygn men enligt standard är 

tidsenheten sekund. 

I samband med att föroreningen tränger in så interagerar de penetrerande molekylerna med 

polymermaterialet. Polymer relaxation (”uppmjukning”) kallas fenomenet när polymerstrukturen sträcks 

och omorienteras som en följd av interaktionen med penetrerande molekyler (Cheng 2009). I PVC-plast 

leder omorienteringen till att materialet sväller och öppnas upp så att mer fri hålrumsvolym skapas (Ong 

et al., 2008). 

Dokumenterade fallstudier 

I USA hade över 100 incidenter rapporterats innan 1992 där dricksvatten blivit kontaminerat till följd 

av att en förorening trängt in i dricksvattennätet, framför allt ifrån kraftigt förorenad jord som omgivit 

ledningen. Incidenterna fördelades lika mellan lågriskområden, såsom bostadsområden, och 

högriskområden, såsom industriområden, bensinstationer och underjordiska lagertankar. 

Föroreningsincidenter i lågriskområden orsakades av avfallstippning eller olyckor med läckage av 

petroleumprodukter, färglösningsmedel eller dylikt (Holsen et al., 1991; USEPA, 2002). 

Petroleumprodukter orsakade 89% av incidenterna, flyktiga klorinerade lösningsmedel (TCE+PCE) 

5% och naturgas 2%. Med TCE avses trikloreten (tri) och med PCE perkloretylen. Andra föroreningar 

som visat sig kunna tränga in i dricksvattensystem är enkla klorinerade aromater, klorinerade och ickeklorinerade 

rakkedjiga alifatiska kolväten samt fenoliska ämnen. Starkt polära bekämpningsmedel, såsom 

paraquat, malathion och atrazin, eller långkedjiga högmolekylära kolväten rapporterades ej utgöra hot på 

grund av dålig genomträngningsförmåga. 

Plaströr var involverade i 98% av incidenterna i USA. Störst andel incidenter inträffade i rör av 

polybutylen (PB) 43%, polyeten (PE) 39% och PVC (15%). Asbestcement, akrylnitrilbutadienstyren och 

tätningsringsmaterial var involverade i vardera 1% av incidenterna. Frekvensen incidenter på 

servisledningar rapporterades vara totalt 22,3 stycken per miljontal serviser och år, varav 16,5 inträffade 


på serviser av PB, 3,6 av PE och 2,2 av PVC. Frekvensen incidenter på huvudledningar var totalt 5,0 st 

per 100 000 mile huvudledning och år, fördelat på PVC 4,6, asbestcement 0,3 och metall 0,1 st (Holsen et 

al., 1991). Totalfrekvensen motsvarar 3,1 per 100 000 km och år. 

AWWA Research Foundation publicerade 2008 en sammanställning av uppgifter om inträffade fall, 

som inhämtats genom en bred enkät, vilken besvarades av 151 VA-verk/VA-bolag i USA (Ong et al 

2008). Tillsammans hade respondenterna 83 360 miles (134 200 km) huvudledningar och 5,4 miljoner 

serviser. Det rapporterades om sex incidenter som rörde huvudledningar och som ledde till antingen 

överskridet gränsvärde i dricksvatten eller till kundklagomål. Det motsvarar frekvensen ett fall per 14 000 

miles (22 000 km) huvudledning. Av dessa sex fall rörde det sig i fyra fall om PVC-rör, i ett fall om rör 

av asbestcement och i ett fall om en gjutjärnledning med tätningsringar av styren-butadien-gummi (SBR). 

I två fall var det förorenande ämnet okänt, i tre fall var det bensin och i ett fall klorerat lösningsmedel. I 

inget av de sex fallen hade man tagit prov på mark eller grundvatten utanför ledningen, varför 

föroreningsgraden i marken tyvärr är okänd i dessa fall. 

Därutöver rapporterades om 47 fall av förorenad mark och/eller grundvatten nära huvudledning, varvid 

resultatet var lyckosamt i den meningen att ingen förorening upptäcktes ha trängt in i 

dricksvattensystemet och inget kundklagomål erhölls. De 47 fallen med lyckosam utgång fördelas enligt 

följande på rörmaterial: 9 PVC, 5 gjutjärn, 32 segjärn, 1 stål. 

Vad gäller servisledningar rapporterades om 44 genomträngningsincidenter, varav 36 gällde 

bensinförorening som trängt in i polybutylenrör (PB), i tre fall hade bensinämnen trängt in i polyetenrör 

(PE) och i två fall genom PVC-rör (Ong et al., 2008). Två rapporter rörde klorerade lösningsmedel som 

hade trängt genom segjärnsrör med SBR-tätning. Slutligen fanns en rapport om en incident där 

asfaltlösningsmedel via en mätarbrunn trängt in i en kopparledning med tätningsring av etylen-propylendien 

monomer (EPDM). I samtliga fall ersattes servisledningen i den förorenade marken med en ny 

ledning av koppar. 

Enligt sammanställningen som gjorts av Ong et al. (2008) kan man se att för järnledningar med SBRtätning 

så har inte genomträngning av huvudledningen noterats vid halten 3,6 mg/kg tetrakloreten (i 

mark), 15,4 mg/l tetrakloreten (i grundvatten), 0,30 mg/l total BTEX (i grundvatten) eller 25,8 µg/l 

bensen (i grundvatten). Däremot har man kunnat konstatera att genomträngning skett av servisledning av 

samma material vid samma haltnivå. Ong et al. (2008) redovisar 562 fall med kopparserviser, 1 PE, 1 PB 

och 13 segjärnsserviser som motstått genomträngning trots känd förorening i marken omkring 

servisledningen. 

Ong et al. (2008) redovisar även huruvida VA-verk/bolag i USA tillämpade särskilda regler vid 

läggning av vattenledning i förorenad mark. 81% svarade att de ej hade särskilda regler, 7% hade regler 

att lägga segjärnledning med resistent tätningsring i förorenad mark, 5% svarade segjärn utan angivande 

om speciella krav på tätningsringar, 1% svarade stålrör, 3% svarade annat material och 3% svarade att de 

hade en regel att inte lägga plaströr i förorenad mark. Tätningsringar som ansågs resistenta var gjorda av 

nitril butadien gummi (NBR) eller fluor-elastomer gummi (FKM) (Ong et al. 2008). 

Referenser 

Cheng, C-L. (2009) Permeation of organic compounds through ductile iron pipe gaskets. Doctoral thesis, Iowa State 

University. 

Holsen, T.M., J.K. Park, D. Jenkins, and R.E. Selleck. 1991. Contamination of potable water by permeation of plastic 

pipe. Journal AWWA, 83(8): 53-56. 

Mao, F., Gaunt, J.A., Ong, S. K. (2009): Permeation of organic contaminants through PVC pipes. American Water 

Works Association Journal, Vol. 101:5, pp. 128-136. 

Mao, F., Gaunt, J.A., Cheng, C., Ong, S. K. (2010): Permeation of BTEX compounds through HDPE pipes under 

simulated field conditions. American Water Works Association Journal, Vol. 102:3, pp. 107-118. 

Malm, A. och Svensson, G. (2011) Material och åldersfördelning för Sveriges VA-nät, och framtida förnyelsebehov. 

Svenskt Vatten Utveckling Rapport 2011-13 

Ong, S.K., Gaunt, J., Mao, F., Cheng, C-L., Esteve-Agelet, L. (2008) Impact of Hydrocarbons on PE/PVC Pipes and 

Pipe Gaskets. AWWA-RF Report 91204. ISBN 978-1-84339-202-6 

Selleck R.E. and B.J. Marinas. 1991. Analyzing the permeation of organic chemicals through plastic pipe. Journal 

AWWA, 83(7): 92-97. 

USEPA (2002) Permeation and Leaching, Issue Paper August 15, 2002, U.S. Environmental Protection Agency. 


Swedish work about development of materials in contact with 

drinking water 

Olivier Rod, Swerea KIMAB, Box 7047, 164 07 Kista, olivier.rod@swerea.se, Lisen Johansson, Swerea 

KIMAB, Box 7047, 164 07 Kista, lisen.johansson@swerea.se 

Drinking water is one of our most important victuals. Usually, treatment of the water takes place in waterworks, 

and by the time drinking water leaves the waterwork, its quality has been raised to meet strict requirements. 

However, during distribution, the drinking water will come into contact with a range of materials which may 

potentially impact its quality. Research has shown that certain substances may be released to the water from 

materials in the system. For example, a case where brass faucets released lead has gained a lot of attention in 

Sweden. A long-term cooperation is missing between the relevant organizations regarding the effects of materials 

in the distribution systems on the quality of drinking water and on the human health. A strategy for development of 

long-term, reliable healthy and environmentally sound solutions is also missing. 

The work presented here, initially financed by Vinnova, is a completely new approach where relevant actors in 

Sweden regarding materials in drinking water distribution systems are working together to make a state of the art 

evaluation and work towards future innovative solutions. The constellation brings together scientists and technical 

experts, regarding both materials and health effects, authorities, trade associations and manufacturers of material 

and water distribution systems. The intention is to share knowledge and to find a joint approach to the issue of 

materials in contact with drinking water. 

The work has to this day consisted in gathering current knowledge, research and experience, identifying potential 

health risks and based on that proposing possible development fields. Legislations and rules have also been 

reviewed. In addition, work was done to broaden the project to a Nordic cooperation. Contacts have were with 

relevant actors in Finland, Norway and Denmark and cooperation opportunities were evaluated. 

Background 

Traditionally, development of materials in contact with drinking water has been concerned about securing the 

mechanical strength and the corrosion resistance of materials in order to avoid water leakage. Material choice 

has therefore been based on mechanical properties and little consideration has been taken to leachate behavior of 

the material. Nevertheless, it is known that materials can influence the quality of the water, for example when 

substances from the material are imparted to the drinking water (Mäkinen, 2008; Nielsen, 2001). Elevated levels 

of chemicals in drinking water could pose a threat to health. Lately, the issue of health effects has been 

addressed, since there have been reports of contamination of drinking water from materials in the distribution 

system. Examples are lead contamination from brass to drinking water, for example from faucets or fittings 

(Lennen Merckx, 2011; Nohrstedt, 2011) or possible water contamination by bisphenol-A after relining 

operation (Miljödepartementet, 2012). 

The release process from materials in the water is complex and depends on a range of factors, such as water 

quality, material age, contact time, flow, geometry, etc, and is therefore hard to predict (Fontanay, 2008). More 

research is still needed to better understand the effect of different parameters on leaching. Critical parameters for 

one type of materials, e.g brass, may be harmless for plastics and vice versa. 

In Sweden, the governmental responsibility is not well-defined. The National Food Agency is responsible for 

implementing parametric values for substances in drinking water, while the National Board of Housing, Building 

and Planning are responsible for implementing regulations for construction products and for controlling products 

on the market. Since the issue of materials and products in contact with drinking water concerns both the water 

and the products, no governmental agency has the general responsibility. This is one of the reasons to why the 

problem has been overlooked for a long time, and to why there is no clear legislation or recommendations about 

this matter. 


Installators, commissioners of building projects and water distributors must make decisions about what materials 

to use in the drinking water system, without any clear health risk based recommendations and the decisions are 

often based on uncertain assumptions. This is a problem for many water distributors, who are responsible for 

providing a safe drinking water. 

Not only is the responsibility divided, but also the knowledge regarding materials in contact with drinking water 

is spread over a large number of actors and organizations. These actors do not collaborate continuously, causing 

a situation where no one has an overall picture of the situation. The development potential lies in the interface 

between the different areas of expertise; all steps in the distribution line need to be represented, from material 

development to installation, distribution, and finally the potential health effects after consumption. 

Project 

This project took place within phase A of Vinnova’s programme “Challenge driven innovation”. The work was 

carried out during five months, from November 2011 to March 2012. 

The project aims to initiate a cross-section collaboration which covers the whole field of materials in water 

distribution systems, and to find a common approach to the issue of materials in contact with drinking water. 

This is done by bringing together a group of organizations, authorities, trade associations, and researchers 

concerned with issues regarding drinking water, materials or their potential health effects. The aim of phase A 

was to collaborate and to make a state of the art evaluation, to identify potential risks and to suggest future 

development work. 

Results 

Constellation 

The main task of this project was to bring together relevant actors. Approximately 40 companies and 

organizations were contacted, some of which joined the constellation, and some of which follow the work and 

form an extended network of the constellation. The participants of the constellation at the end of the project are 

presented in figure 1. 

The strength of the constellation is its width; it includes producers of products (faucets, pipes) and materials 

(brass, copper, polymers, aluminium) as well as installators, water distributors, government agencies, researchers 

within both toxicology and materials and test institutes. The constellation consist of representatives from 

approximately 20 different companies and organizations, which together represent the whole supply chain, from 

the water works, through the distribution, installation, product assessment to the potential health effects. 

The industrial partners and their related trade associations represent the leading manufacturers in Sweden in 

terms of materials and products for water distribution (eg copper, brass, polymers, faucets, fittings, pipes). The 

participating companies are also recognized actors in the global market with growth potential. For all 

manufacturing companies the issue of materials effects on consumer health is highly interesting and important, 

but further product development requires additional skills, such as knowledge about toxicology, that are not 

normally available in these companies. 

Institute of Environmental Medicine at the Karolinska Institutet conducts research in public health, toxicology, 

health effects, etc. Together with the Swedish Chemicals Agency and the Swedish National Food Agency, they 

bring toxicological knowledge to the constellation, and new research findings which constitute the basis for the 

authorities' quality requirements and for sustainable development of health and environmental risk-based 

materials. 

Swerea, SP and SCDA have expertise on materials and test methods and work within the project together with 

manufacturers to develop and test materials and products. 


The government agencies have an important mission to ensure drinking water quality in Sweden through 

appropriate risk management measures such as regulations, recommendations, information and education. 

The companies and organizations that deliver drinking water and those who install and use products for drinking 

water transport complete the consortium by their good knowledge of how materials are used in contact with 

drinking water. They integrate field conditions in the development, knowledge of the needs and requirements 

from the user side, and new trends on the market. 

Figure 1 Participants to the constellation. 

State of the art and possible developments 

The materials present in the different parts of the distribution networks in Sweden were listed, see figure 2. 

Using this list, leaching agents and potential exposure of drinking water consumers to hazardous substances was 

estimated, resulting in a simplified health risk assessment. 

Substances released into drinking water from metallic materials are well known, and health-based risk 

assessments could be performed. Lead from brass components is considered by toxicologists to be the main 

concern today, and the development of low-lead alloys is a priority for brass manufacturers. Private supply water 

however seem to be in many cases more corrosive and pose a greater risk of leaching from metallic materials 

than water from waterworks, where pH and hardness are often adjusted. Long-term tests with private supply 

water should be carried out on different types of materials in order to be able to develop objective information 

and recommendations to well owners. 

No well-founded risk assessment could be done regarding plastic materials, as there is only little data available 

and new materials constantly are introduced to the market. Based on the published studies, comparisons between 


different plastic materials are difficult to make and the results does not apply to leaching in the field. More 

leaching tests on polymeric materials are needed, especially in the field. 

A field survey should also be conducted where water is sampled in different parts of the distribution system and 

analyzed for substances, both from metals and polymers. In this way, areas and materials of risk could be 

identified. 

Figure 2 Main materials in distribution systems with stagnation time 

Compilation of laws, regulations and 

rules, both in Sweden and within the EU, 

shows that they are numerous and often 

vague, and leaves room for own 

interpretations. 

One issue which needs to be clarified is 

the relevance of different test methods 

for assessment and approval of materials 

and products in contact with drinking 

water. Work has been going on for many 

years in an attempt to come to an 

agreement within the EU, as to which 

materials may be accepted for contact 

with drinking water. This work did not 

come up with any common approval and instead, a group called 4MS which includes representative from 

Germany, the UK, Holland and France has been continuing to drive this issue forward. By December 2013, the 

group will present a list of accepted materials, so called positive list, which will apply in these four countries 

(4MS, 2010). This list will most likely act as an unofficial European guideline and will affect the producers and 

users in Sweden. 

At the same time, the National Board of Housing Building and Planning in Sweden is revising the current 

product approval and there is uncertainty on what methods will be used in the future for assessment of materials 

and products in contact with drinking water. For example, an optional product approval called NKB4 is used in 

Sweden to approve faucets. This method is a short term dump-and-fill test and differs greatly from the long term 

rig tests which are used in many other European countries to approve materials in contact with drinking water. 

There is uncertainty about the relevance of this product approval since research indicates that this method does 

not assess the long term behavior of the material, and that the results cannot be related to the drinking water 

parametric value (Johansson, 2012). 

One option for Sweden may be to join the 4 MS system with positive lists, however, it is not fully clarified 

whether or not these positive lists are relevant for Sweden, since water quality differs from other European 

countries, especially since Sweden have a large number of private water supplies, where water may be more 

corrosive than the test waters used to assess material behavior (Aastrup et al., 1995). In Germany, this water has 

been excluded from the test methods, since the opinion is that water supply owners themselves must ensure the 

quality of the water (Rapp, 2012). 

There is a great need from government agencies, consumers, and the Swedish industry for a single group that 

works nationally and with a Nordic perspective on regulation and development of materials in contact with 

drinking water. From this perspective, contacts were taken with research organizations to start a co-operation 

with specialists from Finland, Norway and Denmark. To cover, adapt and influence the work in the EU will be 

very important for both authorities and manufacturers in the coming years. We believe that the constellation 

should be the basis for a group who customize clear national rules based on the EU's work, which is proposed by 

the 4 MS. 


References 

Mäkinen, R. (2008) Drinking water quality and network materials in Finland. 

Publications of Finnish Institute of Drinking Water 5. 

Lennen Merckx, J., Salö, F. (2011) Vattenkran läckte farliga mängder bly. 

Retrieved 2011-09-30 from 

http://svt.se/2.22620/1.2349301/vattenkran_lackte_farliga_mangder_bly 

Nohrstedt, L. (2011) Kranar riskerar förgifta vattnet. Byggvärlden (2011-03-09). 

Retrieved 2011-10-20 from 

http://www.byggvarlden.se/nyheter/energi_miljo/article3122236.ece 

Fontanay, F., Andersen, A. (2008) Metal release to drinking water – an overview of 

Danish and European regulations and investigations. FORCE Technology. 

Nielsen, K. (2001) Metalafgivelse til drikkevand. FORCE Instituttet. Miljøprojekt nr. 603. 

Miljödepartementet (2012). Regeringen förbjuder Bisfenol A i barnmatsburkar. (2012-04-12) Retrieved 2012- 

05-24 from http://www.regeringen.se/sb/d/16083/a/190420 

Aastrup, M., Thunholm, B., Johnson, J., Bertills, U. och Berntell, A. (1995) Grundvattnets kemi i Sverige. 

Naturvårdsverket och Sveriges geologiska undersökning. Naturvårdverket Rapport 4415. 

Johansson, L. (2012) Methods for assessing Pb release from brass to drinking water. Swerea KIMAB (not yet 

published). 

4MS (2010) Declaration of intent between the competent authorities of France, Germany, the Netherlands and 

the United Kingdom concerning the approval of products in contact with drinking water (drinking water quality). 

W-TK-3-4~12-0010 

Rapp, T. Umweltbundesamt (UBA) Federal Environment Agency, Germany. Personal communication 2012-04- 

19. 



Box 47607, 117 94 Stockholm 

Tel 08 506 002 00 

Fax 08 506 002 10 

E-post svensktvatten@svensktvatten.se 

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