Sustainable subdivisions - Construction Innovation

Available technologies and case studiesPenetration of household-scale greywater technologiescan increase community awareness and understandingof broader water resource issues (AlternativeTechnology Association, 2005). Also, for singledwellings, greywater use has broad communityacceptance. While studies have gauged acceptance ofwastewater reuse at larger scales (Po et al. 2003; Poet al. 2005; Hurlimann & McKay 2003, 2004), nonereviewed have examined public perceptions of largescalegreywater reuse.Key learning Household technologies can provideincreased community understanding ofwater resource issues.At Payne Road, greywater from individual householdsis treated via a Biolytix system and the treated effl uentis used for sub-surface garden irrigation. Irrigationvolumes are controlled by soil moisture sensors andsolenoid valves which divert greywater to the sewerif the soil becomes saturated. All unused wastewateris collected to common tanks in the subdivision anddischarged to the sewer system at non-peak hours.Key learning Storage and use of greywater can reducesewer peak fl ows.Similarly to the fi nding for raintanks, the SEW and BaCCsurvey showed a high percentage, 60%, of respondentswere prepared to use greywater for toilet fl ushing, carwashing and garden watering, but only around 5% hadinstalled systems.Greywater system — Pontos AquacycleKey issuesFrom the literature review and case-study sites, anumber of key issues with the implementation ofgreywater collection, storage, treatment and use wereidentifi ed:• Components of household products found ingreywater may affect the environment through soilstructural degradation, increased soil pH and poorplant growth.• There are lengthy approval processes when newtechniques or technologies are used and there is nonational guideline for greywater system testing.• Separation of greywater from blackwater mayrequire extensive plumbing alterations, especially inretrofi t or re-engineering situations.• There is a lack of information on garden design andwatering requirements when greywater is used forirrigation.• High-technology treatments may have highembodied and operating energy requirements andthe capital costs may be high.• The maintenance and management of householdand multi-dwelling greywater systems needs to beconsidered.Greywater system — New Water13