Greywater Harvesting

Greywater is untreated wastewater from bathroom sinks, bathtubs, showers and clothes washers but does not include wastewater from toilets, kitchen sinks or dishwashers. A greywater system is a type of onsite wastewater treatment system that utilizes trenches, subsurface drip irrigation systems, and mulch basins to reuse the graywater for irrigation to save water.

The County of San Diego oversees graywater systems for the unincorporated areas of the County only. For incorporated areas (cities), please contact your respective city for graywater requirements. The purpose of regulating the design, installation and maintenance of graywater systems is to prevent public and environmental health nuisance conditions caused by improper installation or maintenance.

There are three types of greywater systems: Laundry-to-Landscape, Simple, and Complex

If you live within the unincorporated areas of the County, a clothes washer system, which only utilizes graywater from a single clothes washer, can be installed without a permit provided the system is installed in accordance with the Graywater System Requirements for a Single Clothes Washer. Larger graywater systems, which require more extensive plumbing modifications, require a permit.

san-diego-graywater-system-diagram
Greywater

How does a Laundry to Landscape system work?

A L2L system captures graywater from the drain hose of a washing machine and connects to a three-way diverter valve which allows graywater to be directed to either the landscape or the sewer system.

The water is distributed subsurface through 1-inch irrigation tubing with 1/2″ outlets to water specific plants. The L2L system is typically the lowest in cost and easiest to install. 

Is it safe to use graywater?

Graywater is safe to use if you follow procedures and guidelines for constructing, maintaining, and using your graywater system. A safe graywater system is designed to minimize contact with humans and pets.

Additionally, the system should use plant-friendly soap products in order to protect your plants and soil. To help your plants thrive, customers should consider using plant-friendly laundry detergents that don’t contain sodium (salt), boron and chlorine bleach.

Graywater Requirements and Resources by City

While permits are not required for a L2L system in California as long as it complies with the California Plumbing Code, each municipality may have additional requirements.  

Other helpful resources