A larger push is now being made to use graywater for landscape irrigation in an effort to conserve potable water, as evidenced by changing regulations in California. This could also lead to revising the Green Building Code to require graywater systems for new construction and other ‘applicable circumstances.’
Many city regulations only allow use of graywater below ground, yet as this trend continues, new standards for graywater treatment systems would allow wider use. Graywater, typically, is wastewater low in turbidity, from the drainage of bathtubs, showers, bathroom washbasins, clothes washing machines and laundry tubs. It can be used for a variety of water-intensive tasks, from flushing toilets to irrigating lawns.
Home residents use, on average, about 70 gallons of water per person per day. Complete home graywater systems can collect up to 40 gallons of water per person per day. Such systems would demonstrate a significant move toward conserving potable water.
Using graywater for landscape irrigation may have other advantages as well. A 2012 study by the Water Environmental Research Foundation found that many plants used in landscaping benefit from being watered with household graywater. The study found that the nitrogen present in graywater helped plant growth and could potentially reduce or eliminate the need for additional fertilizers.