Graywater

Reuse of household graywater to water plants and trees, or even flush your toilets, can save you water and money!

Stanford has approved graywater reuse as an alternative water supply source option for single family residential customers on the Stanford Campus and Faculty Staff Housing areas within neighboring communities. Graywater is water from bathtubs, showers, bathroom sinks, and clothes washing machines and it can be used to irrigate outdoor landscaping. 

Reusing this relatively clean water source helps reduce the amount of high-quality drinking water needed for household irrigation and reduces the amount of water entering the sewer system for treatment. Systems can be simple (e.g., laundry-to-landscape) or they can be more complex (usually bathroom systems) and incorporate filters and pumps. Graywater systems can help you weather times of drought while maintaining a flourishing landscape. 

New construction or full plumbing remodels can give you access to more graywater sources than are typically available in a retrofit. For example, graywater can also be filtered, disinfected, and pumped for indoor use in toilet flushing (must meet NSF/ANSI 350 standards).

Graywater use, together with water-wise landscaping, conservation and installing water-efficient fixtures and appliances, can preserve our limited drinking water resources, reduce your water bills, and protect our watersheds.

How to Apply

Start by reviewing Stanford’s Graywater Policy for Faculty & Staff Housing Single Family Residences (Stanford Graywater Policy) and determining the details of the systems that you would like to install. 

Next, apply for your proposed graywater system by emailing the Stanford Faculty/Staff Housing Office (fshousing@stanford.edu) the following materials in accordance with the Stanford Graywater Policy:

1. The location and overview of the proposed system,
2. System drawings prepared by a qualified professional architect/engineer,
3. Plans for the designed graywater system that meet the requirements of the California Plumbing Code and Santa Clara County (or appropriate local agency) as well as the Design and Installation Requirements contained in the Stanford Graywater Policy,
4. The Operations and Maintenance Manual for the designed graywater system which addresses the requirements listed in the Stanford Graywater Policy (see the San Francisco Graywater Design Manual Appendix B for templates),
5. For graywater irrigation applications, documentation of a subsurface investigation or percolation test performed under the supervision of a qualified geologist or engineer which includes the soil type and/or percolation rate for determination of the irrigation design, and
6. Signed acknowledgement (Stanford Graywater Policy Attachment A).

• Don't forget to check if Valley Water's $200 graywater rebate applies to your project.