What is greywater?

Greywater is lightly used water from showers, sinks, and washing machines that can be repurposed for gardening, car washing, and toilet flushing. Implementing greywater systems can reduce household water waste by up to 40% and save between 10,000 and 50,000 gallons of drinking water annually for professional installations. The guide outlines both DIY and professional installation options, as well as simple daily reuse methods, while emphasizing safety guidelines such as using the water within 24 hours and avoiding 'blackwater' from toilets.

• Greywater consists of lightly used water from showers, bathtubs, sinks, and washing machines. It is distinct from 'blackwater', which includes water from toilets or diaper washing and is considered off-limits for repurposing.
• Reusing greywater can reduce water waste by up to 40% and lower water bills by the same percentage. Professional systems can save between 10,000 and 50,000 gallons of drinking water per year, though they may cost up to $10,000 to install.
• Greywater can be used for ornamental plants, native grasses, and vegetable plants (provided it only touches the soil), as well as for washing cars and 'bucket flushing' toilets. It should not be used for turf grass or in sprinklers.
• To ensure safety and prevent odors, greywater should be used within 24 hours and should not pool on the surface to minimize human and pet contact. Users must also avoid using water containing bleach or high salt levels on soil.

APA

Harris, L. (2022). What is greywater? World Economic Forum. https://www.weforum.org/stories/climate-action/what-is-greywater/

Chicago

Harris, Linnea. What is greywater? World Economic Forum, 2022. https://www.weforum.org/stories/climate-action/what-is-greywater/.

Wikipedia

{{cite report |last1=Harris |first1=Linnea |title=What is greywater? |publisher=World Economic Forum |date=8 June 2022 |url=https://www.weforum.org/stories/climate-action/what-is-greywater/ |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{harris2022what, author = {Harris, Linnea}, title = {{What is greywater?}}, institution = {World Economic Forum}, year = {2022}, month = jun, url = {https://www.weforum.org/stories/climate-action/what-is-greywater/}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }