Greywater

Left: greywater sample from an office building. Right: Same greywater after treatment in membrane bioreactor

Greywater (or grey water, sullage, also spelled gray water in the United States) refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater from toilets. Sources of greywater include sinks, showers, baths, washing machines or dishwashers. As greywater contains fewer pathogens than blackwater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation, and other non-potable uses. Greywater may still have some pathogen content from laundering soiled clothing or cleaning the anal area in the shower or bath.

The application of greywater reuse in urban water systems provides substantial benefits for both the water supply subsystem, by reducing the demand for fresh clean water, and the wastewater subsystems by reducing the amount of conveyed and treated wastewater.[1] Treated greywater has many uses, such as toilet flushing or irrigation.[2]

  1. ^ Behzadian, k; Kapelan, Z (2015). "Advantages of integrated and sustainability based assessment for metabolism based strategic planning of urban water systems" (PDF). Science of the Total Environment. 527–528: 220–231. Bibcode:2015ScTEn.527..220B. doi:10.1016/j.scitotenv.2015.04.097. hdl:10871/17351. PMID 25965035.
  2. ^ Duttle, Marsha (January 1990). "NM State greywater advice". New Mexico State University. Archived from the original on 13 February 2010. Retrieved 23 January 2010.