Graywater Facts and Figures

Photo Credit:

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.