rapid assessment of drinking-water quality in the republic of tajikistan

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even within an assessment, and priorities have to be set as to which chemical parameters will be tested. Certain physical characteristics of the water should also be included in assessments of water quality, as they are useful indicators of change in quality and are often cited by consumers as reasons for rejecting a source. Physical and chemical parameters may have natural or anthropogenic sources, and their occurrence and concentration can vary over time and by location. The temporal variation is greater in surface waters and shallow groundwater, compared with deep groundwater, and the microbiological quality of such water sources is often poor. The poor chemical quality is primarily related to human activity, but this also means that prevention measures are usually possible and that the contamination may be relatively short-lived if the chemical clears quickly from the water supply. In deeper groundwater, microbiological quality is often very good and therefore chemical quality is a higher priority. Chemical contaminations of deeper groundwater are also more likely to be natural and therefore removal, rather than prevention, may be required. Generally, the quality of deep groundwater is stable and monitoring is required less frequently than for shallow groundwater and surface water sources, both of which are prone to natural (e.g. erosion, run-off) and anthropogenic pollution/contamination. However, a slow flow rate in deep groundwater may lead to long-term contamination problems. Many chemicals affect the palatability and thus acceptability of water sources (e.g. salinity, turbidity and iron; Section 3.3). However, some chemicals constitute a health hazard because of their toxicity (e.g. fluorides, arsenic and nitrates), and others can indirectly lead to adverse health effects because they render the water objectionable and consumers may reject the water in favour of microbiologically contaminated water sources. Commonly, naturally occurring chemicals in water pose a chronic, rather than acute, risk to health and exposures of several years are required to have a health impact. Nitrate Nitrate is one of the most ubiquitous chemical contaminants of water bodies worldwide as it is derived from human activities, particularly from the disposal of human wastes and the use of inorganic fertilizers in agriculture. Nitrate is of concern because of its link to methaemoglobinaemia of “blue-baby” syndrome. Although the actual health burden from nitrate is often considered relatively insignificant (because of breast-feeding practices), it is likely that the health burden is underreported. Nitrate is also of concern because of its properties in water. If it enters a water body in which oxidation is occurring, only dilution and hydrodynamic dispersion are likely to significantly reduce its concentration, until the input load is reduced. Long-term resource problems and costly investments can therefore result if nitrate is allowed to build up in source waters. As nitrate is expensive and difficult to remove from water, blending nitrate-rich waters with low-nitrate waters may be the only viable option. In reducing or non-oxidizing waters, by contrast, nitrate may not be formed, as organic nitrogen would be converted to ammonia by denitrifying bacteria. Water samples at approximately one third (or 642) of all sites visited were tested for nitrate. All complied with the WHO guideline value (50 mg/l) and the national standard (45 mg/l) (Table 3.6). The highest concentrations (up to 22.8 mg NO 3 /l) were in the broad area of Sughd. These findings are in line with current data that indicate that nitrate is not a water quality problem in Tajikistan. Fluoride Excess fluoride is associated with dental and skeletal fluorosis, which may cause severe deformation and disability in susceptible individuals. Excess fluoride in the water should always be suspected if people have mottled teeth or skeletal deformities, even if there are no data. In contrast, a lack of fluoride is associated with dental caries and in some countries fluoride is added to drinking-water to improve dental health. This remains a controversial issue and fluorination may not be the most effective way to reduce the incidence of dental caries. When fluoride levels in drinking-water supplies are high enough to be a health concern, the fluoride usually derives from natural sources, although some may also come from industrial pollution. Fluoride should always be analysed during source development, particularly when developing groundwater sources. 20
Water sources were tested for fluoride at all 1620 sites visited. Of these, 99.7% of the samples met the WHO guideline value of 1.5 mg/l, although only 73.8% met the current national standard of 0.7 mg/l (Table 3.7). Noncompliance was particularly high in Khatlon and Sughd. The maximum fluoride concentration found was 1.95 mg/l, and the median was 0.50 mg/l. These figures are likely to improve in the future, because it has been suggested in the current revision of sanitary norms and water-supply rules (see Section 1.2) that a lower national standard for fluoride be used (of 1.2 mg/l). Arsenic Arsenic accumulates in humans and is concentrated in the food chain. It is associated with skin disease and cancers. Exposure to drinking-water that contains low concentrations of arsenic (
Page 1: RAPID ASSESSMENT OF DRINKING-WATER
Page 4 and 5: WHO Library Cataloguing-in-Publicat
Page 6 and 7: Annexes Annex 1. Rayon database of
Page 8 and 9: Foreword Among the infectious disea
Page 10 and 11: Acronyms GBAO Gorno-Badakhshan Auto
Page 13 and 14: 1 Introduction 1.1 The WHO/UNICEF J
Page 15 and 16: Measuring gender disparities. Data
Page 17 and 18: Microbial parameters. This involves
Page 19 and 20: 2 Methods 2.1 Survey design The met
Page 21 and 22: Figure 2.2 Steps in the design of t
Page 23 and 24: Cluster size. Cluster sizes ranged
Page 25 and 26: Table 2.2 Country-specific survey d
Page 27 and 28: Throughout the field visits, field
Page 29 and 30: 3 Results 3.1 Microbiological param
Page 31: Faecal streptococci Faecal streptoc
Page 35 and 36: Table 3.8 Compliance with the Tajik
Page 37 and 38: Table 3.11 Compliance with WHO sugg
Page 39 and 40: Table 3.13 Results of sanitary insp
Page 41 and 42: Faecal contamination (thermotoleran
Page 43 and 44: comparison was possible, 42.5% show
Page 45 and 46: Table 3.23 Compliance of household
Page 47 and 48: protecting the spring (37.7%). Sani
Page 49 and 50: quality. The Republican SES hopes t
Page 51 and 52: Annex 1. Rayon database of utility
Page 53 and 54: Rayon Water supply Working conditio
Page 63 and 64: Annex 4. Primary stratification a S
Page 65 and 66: Rayons included in the RADWQ survey
Page 67 and 68: Annex 6. Example of a sampling plan
Page 69 and 70: Annex 7. Initial fieldwork plan Fie
Page 71 and 72: Annex 8. Example of a monthly progr
Page 73 and 74: Table 3. # Total number of analyses
Page 75 and 76: The following analyses are planned
Page 77 and 78: Remarks: The Sughd team is continui
Page 79 and 80: No. Description of expense Expense
Page 81 and 82: RADWQ Daily Report Sheet Chemical d

rapid assessment of drinking-water quality in the republic of tajikistan

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