The City of Los Angeles Gray Water Pilot Project Shows Safe Use of Gray Water is Possible

by Bahman Sheikh,

Document Type: Proceeding Paper

Part of: Water Management in the '90s: A Time for Innovation


A year-long study of eight residential gray water systems was conducted in the City of Los Angeles. Soils irrigated with gray water were compared monthly with soils irrigated with municipal potable water. All of the soils and the gray water samples tested negative for Salmonella, Shigella and Entamoeba hystolitica. Occasional Ascaris positives were reported for samples of soil from control and gray-water-irrigated areas. Fecal coliform and Enterococci (indicators of possible human fecal contamination) were not significantly different in the soils compared. It is concluded that gray water used below the surface for irrigation of landscaping does not pose a significant health risk to the public.

Subject Headings: Municipal water | Water supply systems | Water pollution | Public health and safety | Health hazards | Water treatment | Soil water | California | United States | Los Angeles

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