Residential Graywater is broken down into four different types of systems.
Clothes Washer Graywater System
A clothes washer graywater system utilizes only a single domestic clothes washing machine in a one-to-two family dwelling and is the least complicated type of graywater system. No permit is required for a clothes washer system, providing all system design and code requirements are met as outlined in Chapter 16A of the 2019 California Plumbing Code (effective January 1, 2011). Permits are required for systems that include tanks or pumps.
Simple Graywater System
A simple graywater system utilizes a discharge range that exceeds a clothes washer graywater system and is up to 250 gallons per day (gpd) of graywater.
Complex Graywater System
A complex graywater system is the same as a simple graywater system except that there is over 250 gallons per day (gpd) of graywater produced. A complex graywater system is most likely used for multifamily buildings.
Treated Graywater System
The next generation of graywater reuse systems will include graywater treatment devices for expanding its use beyond subsurface irrigation to include surface irrigation and various indoor uses such as toilet flushing. Currently, the use of onsite treated graywater for these expanded uses is prohibited as there are no standards adopted by the State of California for onsite graywater treatment devices. This is expected to change in the not too distant future. Standards already exist for municipally recycled water systems. The National Sanitation Foundation recently published two national standards (NSF 350, NSF 350-1) for small scale graywater treatment devices. LADWP is actively monitored the actions of the State in adopting this standard and other standards for graywater treatment devices.
Standards for the quality of treated graywater and municipally produced Recycled Water are referenced in the 2010 Los Angeles Plumbing Code. Treated Graywater and Recycled Water are required to meet the statewide uniform criteria for disinfected tertiary recycled water. The requirements for treatment are listed in the California Code of Regulations, Title 22 Section 60301.230. Municipally treated recycled water is currently being distributed by the LADWP for use by many parks and golf courses around the city. Recycled Water is being used for non-potable applications including both surface and subsurface irrigation and for toilet and urinal flushing. Recycled Water is not suitable for consumption and is prohibited for potable water use.
Onsite treated graywater systems are already in use in Australia. LADWP is collaborating with Australian regulators and manufacturers to help pave the road for the safe installation and use of these devices in the City of Los Angeles.