Can You Use Washing Machine Water To Irrigate Your Garden?

With the continuing drought and the city's considering moving from voluntary to mandatory water usage restrictions (fines for people who do not cut their water usage by at least 10 percent) could residents perhaps use what is called "gray water," from -- for example, clothes washing machines -- to water their gardens?

Well, they can, but...

Director of Community Development Craig Jimenez said "Monrovia has adopted provisions for the installation of gray water systems as part of the plumbing code, however we do not get many inquiries about these types of systems.  My guess is that since retrofitting a gray water system is more complex than changing out fixtures, and typically requires hiring a professional to install, that influences residents’ decision to pursue this option (or not)."

The city, he said, has adopted the California Plumbing Code, but, he added, "Over the upcoming year, one of our goals is to provide more building/permitting information on the city’s website. That could be one topic we add."

The basic gray water philosophy in the California Plumbing Code, Section 503.0, is that:

Gray water shall be permitted to be diverted away from a sewer or private sewage disposal system, and discharge to a subsurface irrigation or subsoil irrigation system, or disposal field. The gray water shall be permitted to discharge to a mulch basin for residential occupancies. Gray water shall not be used to irrigate root crops or food crops intended for human consumption that comes in contact with soil.

If you are interested, the relevant section of the plumbing code is here.

- Brad Haugaard