Written by IAPMO 6:27 pm Uniform Codes Spotlight


February 23, 2023

1503.2.2 Diversion. The gray water system shall connect to the sanitary drainage system downstream of fixture traps and vent connections through a gray water diverter valve. The gray water diverter valve shall comply with IAPMO PS 59 and be installed in an accessible location and clearly indicate the direction of flow.

Gray water diverter valves are required to divert the gray water to the sanitary drainage when either the gray water is not needed (e.g. plant dormancy, rainy periods or winter season), or when the gray water is hazardous, containing unhealthy contaminants (e.g. hair dye, pesticides, herbicides, cleaning chemicals, solvents, toxins, medications, etc.). PS 59 requires diverter valves to be accessible. An electronic actuator may be included to allow for a switch inside the dwelling to control the valve. See Figure 1503.2.2a for a proper placement of a 3-way diverter valve.

Note: A common type of valve being used incorrectly for greywater diversion are pool and spa diverter valves. These valves have ridges, pockets, 90 degree changes in direction and other aspects that promote the capture of solids in the valve body. These captured solids can foul and compromise the health and safety of the public. Only diverter valves that comply with IAPMO PS 59 shall be used (see Figure 1503.2.2b).

Last modified: February 23, 2023