Gray is the New Green

According to the California Housing Partnership, nonprofit housing providers are likely to struggle with the ability to offer affordable housing and potable water to their low-income residents as a result of the continuing drought conditions in California. With 2014 being the driest year on record for many parts of California, a variety of new ideas for saving water are springing up!

Housing operators are exploring innovative ways to reduce potable water use as the Graywatercost of water increases, including collecting and reusing graywater. Graywater recycling consists of diverting waste water from lavatory sinks, showers, baths and clothes washers for other uses. Traditionally, graywater has been disposed through the dwellings sewer system and not put to beneficial use. Graywater may even be used within a dwelling for toilet flushing, provided an approved onsite nonpotable graywater treatment system is installed.

The use of recycled graywater is subject to state laws and regulations which include the California Plumbing Code and California Health and Safety Code. HCD’s Division of Codes and Standards plays an integral role in researching, developing, and proposing building standards that govern residential graywater recycling systems.

HCD first developed emergency graywater regulations for the 2007 California Plumbing Code while simultaneously proposing regulations for adoption in the 2010 California Plumbing code. Both were approved by the California Building Standards Commission in 2009 after extensive stakeholder consultation and public meetings. The regulations provide details on the minimum requirements for the installation of graywater systems in occupancies regulated by HCD and are intended to provide guidance while remaining flexible to encourage the use of graywater.

Additionally, the regulations make an allowance for the installation of limited types of graywater recycling systems (clothes washer systems) without the need to acquire a permit from the local enforcing agency.

Graywater is most often recycled for use as landscape irrigation, but there is growing interest in using graywater indoors to save valuable potable water that is currently wasted by toilet flushing. Onsite treated nonpotable graywater use is achievable, but likely necessitates dual piping systems (potable and nonpotable water piping), rainwater and graywater collection tanks, plus storage, filtering, disinfecting, and distributing the treated nonpotable graywater back into dwellings.

While the idea sounds appealing, an onsite treated nonpotable graywater system that is compliant with the California Plumbing Code for indoor use can be costly. Much depends on the application and scope of the system. For example, an onsite treatment system designed for a single family home may cost in excess of $8,000.00. Onsite treated nonpotable graywater systems in multifamily housing can range from $40,000 to $90,000, based on the number of units in a building.

With California’s drought continuing to linger, gray may very well be springing up in your neighborhood!

For water saving ideas and drought facts, visit