Stretching Our Water: Graywater

Communities can stretch their current water supplies by creating opportunities for water to perform double duty. For instance, instead of letting soapy water from a bathtub or shower go down the drain to be carried away to a treatment facility, it can be redirected and reused onsite in the garden or to irrigate outdoor landscaping. This type of arrangement is a part of a graywater system.

More than half of the water used within the home – typically 60 gallons a day per person – is suitable for reuse. Reuse of water used in homes (domestic graywater) is a simple, affordable practice that can help individuals and communities use water more wisely. Shower, sink and laundry water comprise 50% to 80% of residential “waste” water, which may be reused for other purposes, especially landscape irrigation.

During droughts, some people resorted to using buckets to transfer bath water to the garden. This practice can be made more convenient by putting two drains in a bathtub or sink – one drains to the garden, the other to the sewer.

Using graywater instead of drinking quality water for landscape irrigation can keep lawns and gardens green – even in times of drought – and alleviate water demand in areas prone to water shortages.

Graywater can also be better for a garden than using treated drinking water. Soap and other products in wastewater are rich in compounds that can pollute waterways, wear out septic systems, and overburden wastewater facilities. However, these same pollutants – phosphorous, nitrogen, potassium and proteins – are rich sources of nutrients for fruit trees, landscaping and gardens.

State law permits cities and counties to allow the sanitary reuse of graywater. Graywater systems are affordable and simple to install, especially if done at the time of construction. A workable, code-compliant, graywater irrigation system sends water from showers, sinks and other graywater sources away from blackwater before they mix and go to a sewage system.

The City of Santa Rosa is using financial incentives to promote such projects- their Graywater Rebate Program offers $75 per qualifying fixture that reroutes graywater and $200 for every 1,000 gallons of sustained reduction in monthly water consumption.

Cities and counties can also require dual drains be installed for reusing water in new construction. Another option is to adopt a water recycling ordinance to maximize resource conservation and streamline implementation of water recycling projects in conformance with state law (The Ahwahnee Water Principles: A Blueprint for Regional Sustainability).

General Plan language and model programs can be found in the LGC’s Ahwahnee Water Principles: A Blueprint for Regional Sustainability or in the water section of the “Energy Aware Planning Guide” that the LGC contributed in partnership with the California Energy Commission and Cambridge Systematics: