Graywater System Design Guidelines

Client: Urban Watershed Management Program, San Francisco

Graywater is water from showers, bathtubs, washing machines, and bathroom sinks. In an effort to promote water conservation, the San Francisco Urban Watershed Management Program hired WRE to prepare a guidance manual for the reuse of graywater for outdoor irrigation.

The goal of the manual was to provide information for the community, general public, and technicians regarding the design, permitting and operation of graywater systems in San Francisco. The manual describes how to estimate a home’s graywater production, size a system, assess the infiltration capacity of a site’s soils, and understand whether or not a permit is required.

The manual provides detailed instructions for building a laundry-to-landscape system as well as a general description of the selection and design of other more complex graywater systems.