Greywater | Central Coast Greywater Alliance

California Greywater Law

Greywater is waste water from laundry machines, bathroom sinks, showers, and bathtubs. California law does not allow greywater use from kitchen sinks or dishwashers. In January 2010, the California Building Standards Commission adopted greywater guidelines into the California Plumbing Code. The California Plumbing Code Chapter 16 facilitates water conservation, relieves stress on private septic systems, makes legal compliance easily achievable, and provides guidelines for avoiding potentially unhealthful conditions. Chapter 16 classifies greywater systems as clothes washer systems, simple systems producing 250 gallons a day or less, and complex systems that produce 250 gallons per day or more. The code requires a construction permit for any greywater system that makes changes to a home’s drain/waste plumbing connected to clothes washers, showers, bathtubs, and bathroom sinks. The code allows residential graywater landscape irrigation from washing machines without a construction permit if the system meets all performance guidelines in the code (see Greywater System Requirements below).

Designing Your System

The most reliable, economical, and low-maintenance greywater system designs require no pumps, filters, or storage tanks. Greywater is piped directly to the receiving landscape and distributed into mulch basins. The biology of the mulch basin and surrounding soil is the treatment system that digests organic debris, soap, and any potential pathogens.

Whereas laundry-to-landscape systems use the clothes washer’s internal pump to distribute greywater to mulch basins, branched drain systems from bathroom sinks, showers, tubs, and interior laundry rooms rely on gravity to send greywater into mulch basins through a branched drain irrigation system. Landscapes that are flat or uphill from the greywater source may require an effluent pump system. Greywater to drip irrigation is possible, but requires pumping, filtration, and backflow prevention, all of which increase overall system cost and maintenance.

Greywater System Requirements

All greywater irrigation systems must comply with the following guidelines to protect the environment and avoid system failure:

■ Any greywater system that includes a connection to a potable or municipal water supply must have an approved, backflow prevention device. Laundry to landscape greywater irrigation systems that are exempt from permitting must have no connection to the potable water supply or an external pump.

■ The greywater system design must include an accessible, clearly labeled, three-way valve that diverts the greywater back to the building sewer. Greywater should be diverted to the building sewer during the rainy season between November and April.

■ The greywater must not leave the property where it came from or come within 100 feet of any creek, wetland, or waterway.

■ The groundwater table must be lower than 3 feet from the lowest greywater irrigation or disposal point.

■ Each release point of the greywater irrigation system must be covered with at least 2¨of mulch, rock, soil, or a soil shield. Sprinkler irrigation and ponding of greywater are not allowed!

■ Water used to wash diapers or other infectious garments must be diverted to the building sewer.

■ Greywater may not contain hazardous chemicals.

■ Greywater may not be used to irrigate root crops or other edible crops that touch the soil.

■ An operations and maintenance manual for the greywater system must be provided by the installer and must be transferred to the new tenant or owner for the life of the greywater system.

■ Greywater irrigation systems must be located a minimum horizontal distance away from the following landscape features:

  • Landscape Feature Minimum Horizontal Distance from Greywater Irrigation System
  • Building structures 2
  • Property line adjoining private property 1.5 ft
  • Water supply wells 100 ft
  • Streams, Rivers, Lakes, Wetlands, and High Tide line of Ocean 100 ft
  • Sewage pits or cesspools 5 ft
  • Sewage disposal field 4 ft
  • Septic tank 5 ft
  • Onsite domestic water service line 0 ft
  • Pressurized public water main 10 ft

For detailed information regarding required setbacks for greywater tanks, greywater irrigation fields, and greywater disposal fields, see Table 1602.4 of Chapter 16 of the California Plumbing Code.


Santa Cruz County Residents

To build a greywater system that is connected to a shower, tub or sink, a Building Permit is required. For guidelines on how to obtain a permit please see the Santa Cruz County Planning Department website:

Drought Water Shortage Contingency Plan.pdf

Residential Toilet Rebate Program

Central Water District (CWD) customers replacing a toilet using 3.5 gallons per flush (gpf) with a high efficiency toilet (HET) are eligible for a credit of $50.00.

  • HETs are toilets that flush at a rate of 1.28 gpf
  • HETs use approximately 7,500 gallons of water per year
  • Retrofitting an old toilet with an HET can lead to a savings of up to 24,600 gallons per year, depending on the size of your household

In order to receive the credit, customers must turn in a completed application along with the receipts for the purchase and installation of the HET.

Residential Toilet Rebate Program Applications may be obtained by contacting Christine Burnett at the Central Water District office at 831-688-2767 or by email at

You can also download and print the application by clicking the attachment below.

Residentail Toilet Rebate Program Application_CWD.pdf

Residential Clothes Washer Rebate Program

Central Water District (CWD) customers replacing a conventional clothes washer with a high-efficiency clothes washer are eligible for a credit of $50.00.

  • Clothes washing accounts for approximately one-fifth of indoor water use for the average home. High efficiency clothes washers can use 35% less water and 20 percent less energy than conventional models.
  • High efficiency clothes washers include both front-loading and top-loading models. To qualify for the rebate, the high efficiency model purchased must be rated as Energy Star compliant.

In order to receive the credit, customers must turn in a completed application along with the receipt for the purchase of a new high-efficiency, Energy Star compliant washer. Please see the information below for rebate program rules and requirements

Residential Clothes Washer Rebate Program Applications may be obtained by contacting Christine Burnett at the Central Water District office at 831-688-2767 or by email

You are also welcome to stop by the Central Water District office at 400 Cox Road, Aptos.

Rules and Requirements:

  1. Rebate application must be submitted within 90 days of item(s) purchase. An original, dated sales receipt showing itemized cost for the rebated item(s) must be provided. Please make a copy of your receipt as original receipts will not be returned. For purchases made online please provide a print out of the final invoice and the original packing or delivery slip.
  2. All rebate applications must be signed by the legal property owner.
  3. Applicant must replace a conventional clothes washer with a high efficiency, Energy Star compliant clothes washer to be eligible for the rebate.
  4. The number of clothes washer rebates is limited to 1 qualifying washer at the property.
  5. The rebated clothes washer must be installed at an existing Central Water District (CWD) service address and must be installed prior to any rebate request. New development is not eligible for rebates.
  6. Rebates are applied as a $50.00 credit that will appear on a subsequent water bill. The account must be in good standing to receive a credit.
  7. Installation of the rebated device is the sole responsibility of the applicant, as is determination of the adequacy and compatibility of the existing plumbing system.
  8. CWD does not endorse specific brands, products or dealers; nor does it guarantee materials or workmanship; acceptance of such is the customer’s responsibility.
  9. CWD assumes no responsibility or liability for any damage that may occur to an applicant’s property as a result of participation in this program.
  10. CWD may at any time modify, suspend or terminate this program without prior written notice.

Note: Rebates are limited to $100.00 per qualifying household. Rebates can be applied through the installation of one high efficiency washer or one high efficiency washer and one low flow toilet or two flow toilets.