title: Field study of the composition of greywater and comparison of microbiological indicators of water quality in on-site systems.
abstract: Thirty on-site greywater systems were sampled to determine greywater characteristics and practices in the field. Kitchen greywater was present at eight sites and urine was included at seven sites. These non-traditional sources resulted in significantly higher concentrations of enterococci and 5-day biochemical oxygen demand (BOD5) in greywater. Even with the removal of these sources, the concentrations of microbial indicators indicated high levels of contamination could occur across all greywater sources, including "light" greywater. Using multiple microbial indicators showed that all samples had the potential for faecal contamination. Bacteroidales markers were confirmed in treated greywater and in each greywater source, highlighting the potential for human faecal contamination. Although Escherichia coli was absent in treated greywater recycled to the house, other microbial indicators were present; hence, caution is required in using E. coli concentrations as the sole indicator of microbiological water quality. High BOD5 or total suspended solid concentrations exceeded the levels recommended for effective disinfection. Subsurface irrigation, which is assumed to provide a five-log reduction in exposure, is a suitable reuse option for non-disinfected greywater. Only half the occupants had a good understanding of their greywater systems and 25 % of systems were poorly maintained. Elevated microbial indicator contamination of greywater sludge is a potential hazard during maintenance.
authors.affiliation: Ara Institute of Canterbury, PO Box 540, Christchurch, 8140, New Zealand. margaret.leonard@ara.ac.nz.
authors.forename: Margaret
authors.identifier: http://orcid.org/0000-0002-3691-6841
authors.initials: M
authors.lastname: Leonard
authors.affiliation: Institute of Environmental Science and Research, PO Box 29-181, Christchurch, 8041, New Zealand.
authors.forename: Brent
authors.initials: B
authors.lastname: Gilpin
authors.affiliation: Institute of Environmental Science and Research, PO Box 29-181, Christchurch, 8041, New Zealand.
authors.forename: Beth
authors.initials: B
authors.lastname: Robson
authors.affiliation: Health Protection NSW, 2060 Locked Mail Bag 961, North Sydney, NSW, 2059, Australia.
authors.forename: Katrina
authors.initials: K
authors.lastname: Wall
mesh_terms: D057919:Biological Oxygen Demand Analysis; D004203:Disinfection / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods*; D004926:Escherichia coli / Q000302:isolation & purification; D006801:Humans; D009520:New Zealand; D059027:Recycling / Q000379:methods*; D012722:Sewage / Q000032:analysis / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology; D060753:Water Quality
chemical_list: D012722:Sewage; D062065:Wastewater
keywords: Greywater; Microbial indicators; Treatment; Water reuse