Graywater Facts and Figures

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In the United States, the rough estimate of per capita graywater production is 28 gallons per person per day (AWWA 1999), or about 10,000 gallons per person per year. For a four-person household, this would total 40,880 gallons per year of graywater. Based on the USGS estimates of 124 gallons per person a day in California (indoor and outdoor use), a four person household uses approximately 181,400 gallons each year. This same household can expect to defray 22% of their potable water needs by utilizing graywater.

 

This number may be higher or lower depending on the household and the water efficiency of the fixtures. Given that most households spend a minimum of 50% of their potable water on landscape irrigation, saving 22% by using graywater in the landscape is a simple answer to unnecessary potable water use in landscape.