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  • Suresh Venkatraman

Greywater 101

Recycle Your Water

Don’t let expensive, imported tap water drain away. Reuse it on the garden. Greywater, once a subversive act, has now reached mainstream.  Greywater, also known as graywater, is wastewater from washing machines, bathroom sinks, showers and tubs. Route it outside through a subsurface drip system and plants will love it. Dirt, soap, oils, hair and certain cleaning products in greywater are safe and even beneficial as irrigation water. If released into creeks, the nutrients in greywater become pollutants, but to plants, they are valuable nutrients. Over 50% of water used inside the house is suitable for greywater use, a potential and significant reduction in sewer and septic demands. Wastewater from toilets or kitchen sinks, designated as blackwater, is never recycled in greywater systems. Unfiltered greywater cannot be stored more than 24 hours or it is classified as blackwater.

Simple to Complex, Know the Code

The simplest method of greywater reuse is to capture shower warm-up water in a bucket and use it to flush toilets or water plants. The most common residential greywater system is laundry-to-landscape. California law allows laundry-to-landscape and single-fixture (shower or bathroom sink) to landscape use without requiring a permit. More complex systems require permits and inspections. The Packard Foundation’s LEED platinum building in Los Altos re-routes sink basin and HVAC condensation water to flush toilets and irrigate plants.

Better For You

“When I built my first greywater system I investigated the contents of my soaps and detergents and found they contained toxins and carcinogens, even though they were advertized as all “natural”. I changed all the products I used so they would be good for me and for my plants.” Laura Allen, founder of Greywater Action. Boron, bleach and other common chemicals in laundry soaps are toxic to plants and not so good for humans either.

Conservation is still the best approach to reduce your water budget. In Los Altos Hills, irrigation accounts for nearly 70% of residential water usage. Climate suitable plants, such as California native plants, significantly reduce water requirements. Make a water pledge and reduce your draw of water from California’s sensitive watersheds.Learn more at, Santa Clara Vally Water District (

Attend a DIY Graywater Workshop March 23, 10am – 1pm. Contact Kit Gordon at for more information or register on Eventbrite.

The workshop is sponsored by Los Altos Hills Water Conservation Committee and GreenTown Los Altos, a non-profit serving Los Altos and Los Altos Hills.

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