California Graywater Codes
January 27, 2010 (2007 CPC, Title 24, Part 5, Chapter 16A, Part I – Nonpotable Water Reuse Systems)
The following is a collection of excerpts that summarize the code.
Keep in mind “a city, county, or city and county or other local government may,after a public hearing and enactment of an ordinance or resolution, further restrict or prohibit the use of graywater systems. For additional information, see Health and Safety Code Section 18941.7.”
"Graywater" includes but is not limited to wastewater from bathtubs, showers, bathroom washbasins, clothes washing machines, and laundry tubs, but does not include wastewater from kitchen sinks or dishwashers.
Mulch Basin. A type of irrigation or disposal field filled with mulch or other approved permeable material of sufficient depth, length and width to prevent ponding or runoff. A mulch basin may include a basin around a
tree, a trough along a row of plants or other shapes necessary for irrigation or disposal.
Irrigation Field. An intended destination for graywater in the receiving landscape including but not limited to a drip irrigation system, mulch basin, or other approved method of dispersal for irrigation purposes.
Requirement for 2” covering
In general, any irrigation system must avoid graywater contact by being covered with 2” of material:
(G) Graywater shall not be used in spray irrigation, allowed to pond or runoff and shall not be discharged directly into or reach any storm sewer system or any surface body of water.
(H) Human contact with graywater or the soil irrigated by graywater shall be minimized and avoided, except as required to maintain the graywater system. The discharge point of any graywater irrigation or disposal field shall be covered by at least (2) inches (51 mm) of mulch, rock, or soil, or a solid shield to minimize the possibility of human contact.
(I) Graywater shall not be used to irrigate root crops or edible parts of food crops that touch the soil.
The code describes three types of systems:
Clothes Washer System. A graywater system utilizing only a single domestic clothes washing machine in a one- or two-family dwelling.
This method cannot use a secondary pump and relies either on the washing machine pump or gravity to irrigate the garden areas.
The amount of water from the washing machine is considered to be 15 gallons per person per day, e.g. 60 gallons per day for a 4 person household.
A construction permit is not required for the Clothes Washer System A construction permit shall not be required for a clothes washer system which does not require cutting of the existing plumbing piping provided it is in compliance with Section 1603A.1.1.
Simple System. A graywater system serving a one- or two-family dwelling with a discharge of 250 gallons (947 L) per day or less. Simple systems exceed a clothes washer system.
A construction permit is required for a simple system.
Complex System. Graywater systems that discharge over 250 gallons (947L) per day.
A construction permit is required for a complex system.
A written construction permit shall be obtained from the Enforcing Agency prior to the erection, construction, reconstruction, installation, relocation or alteration of any graywater system that requires a permit.
No construction permit for any graywater system shall be issued until a plot plan with appropriate data satisfactory to the Enforcing Agency has been submitted and approved. When there is insufficient lot area or inappropriate soil conditions to prevent the ponding or runoff of the graywater, as determined by the Enforcing Agency, no graywater system shall be allowed.
1604A.0 Drawings and Specifications. Graywater systems for which a construction permit is required may be subject to submittal of plans and details of the proposed graywater system necessary to ensure compliance with the requirements of this chapter.
Identification of the groundwater level and soil absorption qualities at the site shall be included in the plans or provided to the Enforcing Agency.
1605A.0 Inspection and Testing.
(A) Inspection. A graywater system for which a construction permit is required shall be subject to inspection by the Enforcing Agency and such construction or work shall remain accessible and exposed for inspection purposes until approved.
(B) In order to determine the absorption quantities of questionable soils other than those listed in Table 16A-2, the proposed site may be subjected to percolation tests acceptable to the Enforcing Agency. Exception: Irrigation fields in compliance with Section 1611A.2, which only utilize drip type emitters.
A washer machine system, without an extra pump, producing 60 gallons per day, does not need a permit.
Any other style of system e.g. re-using shower water, or using a pump, must have a construction permit.
Construction permits require a plot plan with supporting data, drawings and plans of the graywater system, and a site test by the agency after installation. If drip emitters are not used a percolation test will be required as well.