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Office of Sustainability and the Environment
Water Water

Graywater Definition: 

California state regulations define graywater is as untreated wastewater that has not been contaminated by toilet waste or unhealthy bodily wastes. Graywater includes wastewater from bathtubs, showers, bathroom washbasins, clothes washing machines, and laundry tubs, but does not include wastewater from kitchen sinks or dishwashers.

Graywater Uses:

Untreated clothes washer graywater systems can use the water in subsurface drip irrigation and/or mulch basins. Graywater shall not be used in spray irrigation, allowed to pond or runoff, allowed to be discharged directly into or reach any storm water system or any surface body of water, and shall not be used to irrigate root crops or edible parts of food crops that touch the soil.

On-site treated non-potable graywater systems are permitted to supply toilets, urinals, laundry washing, cooling tower makeup water, and trap primers for floor drains and floor sinks, above and below ground irrigation.

Graywater Regulations:

Graywater systems must meet all requirements in Chapter 16 of the California Plumbing Code.

Graywater systems must also meet the County of Los Angeles Public Health's Guidelines for Alternate Water Sources -- Indoor and Outdoor Non-Potable Uses (aka Matrix 2.0)

Graywater Permits and Inspections:

  • A permit is not required for clothes washer graywater systems in Santa Monica.
  • A single-trade permit is required for all other graywater systems in Santa Monica.
  • The permit fee has been waived for graywater systems.
  • Plans must be submitted online.
  • Inspections are required by City staff and Los Angeles Public Health staff.
    • Call (310) 458-2202 or (310) 458-8358 to schedule:
      • A. Underground plumbing inspection as pipes and system for both irrigation and graywater are being installed.
      • B. Plumbing rough-in inspection once pipes for irrigation and graywater are installed but before they are covered.
      • C. Electrical inspection as system is installed.
    • Call to schedule (310) 458-8535 to schedule:
      • Backflow protection.


A few rules of thumb:

  • For minimum hassle, the things you want to water should be downhill from the lowest point in your graywater system. Simple systems cost less and will be cost‑effective in a shorter period of time.
  • No matter how much graywater you produce, you will probably still need a conventional irrigation system on at least part of your property.
  • Putting in a graywater system is not something that is going to save you a lot of money. But it is one of the most effective things you can do to cut your exterior water use and reduce the waste stream from your home.

Questions?  Email or call 310.458.8459


Last updated: Monday, 07/10/2017
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Santa Monica Office of Sustainability and the Environment
1685 Main St., Santa Monica, CA 90401 · (310) 458-2213 · TTY (310) 917-6626