Saturday, April 10, 2021


50 Shades of Graywater

I have done a little research on graywater and like the movie; there are many shades of gray we are not familiar with. I am going to write about the basics of graywater usage. I think there are easier ways to save water than using graywater but if you would like to look into it here are the basics.

What is graywater?
Graywater is untreated wastewater collected from bathtubs, showers, washing machines and bathroom sinks and reused for outdoor irrigation or toilet flushing. It does not include wastewater from kitchen sinks or dishwashers. Of course, it does not include toilet water.

Is graywater allowed in my area and do I need a permit?
Current California law (as of January 1, 2014) graywater is legal but laws can change. A permit is not needed for simple clothes washing system.

Simple systems
Simple systems can include buckets of water collected from warming up the shower water. Just be sure to use the water within 24 hours of collection. In 2009 California declared it legal to divert washing machine water to home gardens. This is the easiest way to use graywater and does not need a permit.

Where do I use graywater?
Graywater should only be used on ornamental plants. It should not be used on edible plants. Use graywater friendly soaps, shampoos and detergents. The quality of your graywater depends upon what goes into it.

Benefits of graywater
Using a graywater system to irrigate landscape plants can conserve water by recycling water otherwise destined for a treatment plant. Most graywater systems will not supply enough water to irrigate the entire yard but it can supplement your irrigation.

Risks and problems of graywater
There has been limited research on the risks of graywater. Here are some possible risks.
•    Can have pathogens such as E. coli, salmonella.
•    Can contain, bleach, boron, salts.
•    Cannot store it over 24 hours.
•    Clogs drip systems.
•    Don’t use near a creek or river.
•    Don’t let it run off your property.
•    Need to use a mulch basin.
•    Don’t use on acid loving plants.
•    Don’t use on your lawn.

There are many resources for graywater on the internet. Please be careful what resources you use. I used resources from the University of California, several UC Master Gardener programs and Sunset.

The Master Gardeners of Colusa County can be contacted by: Email Phone (530) 458-0570. office, 100 Sunrise Blvd., Ste. E, Colusa, on Tuesdays between the hours of 9:00 am to 4:00 pm. – or visit us at our plant clinics, farmers markets, Colusa County Fair and at other area events.

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