Greywater Made Easy
By Lee Oliphant UCCE Master Gardener
Q. Where do I start in setting up a graywater system for my garden? Carol, Cambria.
Using greywater is an excellent way to reduce the waste of a valuable resource and minimize water that enters waste water collection systems. Greywater is used household water from sinks, showers, bathtubs, and washing machines. It does not include water from toilets, kitchen sinks (remember that raw chicken you rinsed), or dishwashers. Greywater should not be used on any edible plants in the garden.
While you can carry out buckets from your sink, shower, or tub, there is an easier (on your back and shoulders) way to use non-potable water for outdoor irrigation. A greywater system uses gravity to redirect wastewater from a washing machine to the yard, rather than to the sewer, and is called Laundry to Landscape Greywater System. A construction permit is NOT needed for this system as long as the system does not alter plumbing by cutting into pipes. A hose to the house exterior is attached to the washer hose and must follow the Health and Safety code 17922.12. This system requires a 3-way valve that allows you to switch between a greywater and sewer system. Water must be diverted to the sewer if used for dirty diapers, infectious contaminants or if it contains cleaning products harmful to plants such as bleach, softeners, and dyes.
According to chapter 16 of the California Plumbing Code, greywater cannot be stored and must be used within 24 hours from the time of collection. Immediate use minimizes the development of bacteria and other harmful pathogens.
There are other, more complicated systems than the Laundry to Landscape Greywater System. However, both require permits and plumbing alterations. It is always wise to check with SLO County and your specific city before beginning your greywater project.
Identify detergents that are safe for the environment before using the Laundry to Landscape Greywater System. Become familiar with plants that do well with greywater such as madrone, western redbud, coffeeberry, toyon, manzanita, rosemary, ceanothus, salvia, lavender, and penstemon. They will survive the alkaline environment created by greywater.
For more information on using greywater in the landscape, download Use of Greywater in Urban Landscapes in California: http://anrcatalog.ucanr.edu.