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Greywater: Harvesting an Abundant Resource

By Golden Love

Almost 7 million gallons of water go down the drain everyday in Santa Cruz, California; much of this water could be used for watering gardens. How can this water be harvested?

In February of this year, a new state plumbing code was adopted in California that exempts some of this water from the permitting process.
raingarden This article will briefly review the new code, discuss how greywater can be applied to the garden, and explain how the community and state can benefit.

Greywater is defined by the State of California as all sink, shower, bath, and laundry water. Kitchen, dishwasher, and toilet water are considered to be “black” water. The new California plumbing code has important guidelines that need to be followed when reusing greywater. Here are a few of them: Greywater needs to be distributed under 2 inches of mulch, preferably into a mulch basin, or covered by a “greywater outlet shield;” Greywater needs to be dispersed at least 2 feet from buildings and 1.5 feet from property lines, never to neighboring properties or streets, and at least 100 feet from bodies of water; Excess water during the winter months, toxic substances like chlorine and boron, and soiled diapers must be diverted to the sewer or septic system. For more detailed information about the new code, click here.

FlowingtapOne of the more popular greywater systems is the Laundry to Landscape Irrigation System. This is permit exempt and can be used in most homes to water portions of the garden. It is hooked up to a washing machine and run into the garden, and is most effective with fruit trees, perennials, and vegetables. A diverter valve near the washing machine controls flow to either the landscape or septic/sewer system. Multiple zones can also be set up in the garden to increase the coverage. Older washing machines using 40-50 gallons of water per load offer this kind of expanded use. It is recommended that low-salt liquid soaps or laundry washing balls and plant-based cleaners be used for plant health and the environment.

Greywater is a vital part of the movement toward “Water Neutral Gardens,” zero use of municipal or well water to irrigate landscapes. Since our climate here in California has dry summers, greywater fills the gap when our cisterns or rain barrels might run dry or when there are water restrictions due to drought. A “Water Neutral Garden” is possible by utilizing greywater in combination with drip systems attached to cisterns, native plants and grasses, and rainwater harvesting.

santa cruzUsing alternatives such as greywater makes sense in the arid climate of Santa Cruz. It is an appropriate use of an abundant resource and can reduce harmful impacts of more water diversions, dams, and a desalinization plant. Desalinization will affect the biology of our marine sanctuary and increase global warming gases through increased electrical use. The cost to build and maintain such a plant would increase water rates considerably.

Raingarden display at the Santa Cruz County Fair photo by Golden Love. All other photos are from Wikimedia Commons.

Golden Love is coordinator of the Ecological Landscaping Assocation Monterey Bay Working Group and co-coordinator of the Central Coast Greywater Alliance in Santa Cruz, California.