Grow For It!: Harness the rain — use your greywater

By From page B3 | March 19, 2014

MasterGardener logo RGBRain at last!

Wouldn’t it be nice if you could store it for future use?

Well — you can and without too much trouble. You can also look at the possibility of using your own greywater in the landscape. How wonderful that these water resources are available on your own property and free for the taking.

There are a few guidelines to follow to ensure harvesting and using both will be done effectively, safely and legally.

Let’s look at rainwater first. It is amazing to see that even a relatively small 1,500 square foot Placerville house could generate almost 5,000 gallons of water in an average year. One such house generated enough rainwater last year from just a garden shed to water half their vegetable garden for the summer. This year they expanded the shed roof and despite the low rainfall have already nearly filled a 2,500 gallon tank. You too can benefit from rain.

Some things to consider are how to store the water: barrel, tank or perhaps an old plastic pool?

Next, consider whether the cost is worth it and if water quality will be adequate. In general, the soft rainwater is great for plants but look at your roofing material and for possible critter contamination.

Another alternative is to let the water go straight to plants by digging a simple trench to divert water from, say, your driveway onto trees and shrubs. Watch for pooling, which means you are diverting too much water and need to devise an escape for it onto other plants.

One problem with rainwater can be that it falls almost exclusively here in October through May, but our gardens need water mostly in May through September. This can be overcome with storage but another option is to use greywater.

Greywater is the untreated waste water from your washing machine, shower and bathroom sinks. It does not include water from your toilets or dishwasher and kitchen sink.

Contrary to what many think, it is legal to use greywater provided certain guidelines are followed.

A system that diverts your laundry water does not even need a county permit, though as of Jan. 1 other greywater systems do. Some of the main requirements are that you should not store the greywater more than 24 hours; it must stay on your own property, must not be used on edible parts of plants and is best delivered beneath several inches of mulch. A full set of requirements can be found in the California Plumbing Code, especially chapter 16.

The simplest and perhaps cheapest way to use greywater is through what is known as the “laundry to landscape” system.

To find out about this method and other ways of using greywater and rainwater, come to the Saturday, March 22 Master Gardener class at the Government Center Hearing Room, Building C, 2850 Fairlane Court in Placerville.

The free class is titled Towards Sustainable Gardening: Rainwater Harvesting and Greywater Use and will run from 9 a.m.-noon. You will learn how to design simple rain and greywater systems, avoid contaminants, calculate water amounts and follow all the legal requirements.

Master Gardeners are available to answer home gardening questions Tuesday through Friday, 9 a.m.-noon by calling 530-621-5512. Walk-ins are welcome at the office, located at 311 Fair Lane in Placerville.

For more information about the public education classes and activities go to the Master Gardener Website at Sign up to receive the online notices and e-newsletter at You can also find Master Gardeners on Facebook.

Alice Cantelow

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