Don't Let Rainwater and Greywater Go Down the Drain

The average American uses 100 gallons of water a day in his or her home. In the Bay Area, up to 80 percent of all home water use goes toward landscaping.

I learned these statistics at Millbrae’s on Jan. 27 at the . An audience of about 25 eco-minded folks gathered that evening to learn how collecting rainwater and greywater conserves water and how they could reduce their water bills. The workshop was led by John Russell, the owner of WaterSprout, an Oakland-based company that installs rainwater and greywater systems throughout the Bay Area.

Russell covered the many types of rainwater and greywater collection systems, which can range from a $300 DIY project put together with a rain barrel and a hose, to a $10,000 professionally installed system with pumps and valves.

For example, a home with a 2,000-square-foot roof that gets 24 inches of rainfall a year can collect about 30,000 gallons of water annually. The simplest rainwater system would be a barrel that collects rainwater from the roof and channels the water through a hose to a small area of your garden. This simple system would make an easy DIY project and is ideal for watering a winter veggie garden. You could also collect rainwater through a drip irrigation system that either uses gravity or pumps to deliver water throughout your yard. To get rid of the debris, water picks up things such as leaves, bird waste and the like as it travels down the roof. These systems have filters that would need to be replaced yearly.

You, too, can prevent water from being wasted

The problem with using rainwater to irrigate your yard, Russell pointed out, is that your plants often don’t need extra water during the rainy season.  Russell believes that the best use of rainwater is to bring it indoors for your toilets and washing machine. This kind of rainwater system uses additional filters and UV lights to disinfect water to make it safe for indoor use, as required by state codes. This system needs a city permit, and it is probably best to get it installed by a professional.

Another way to conserve water is to collect greywater. Greywater is the used wash water from your showers, baths, washing machines and bathroom sinks and not the water from the toilet, kitchen sink or a washing machine load with the dirty diapers in it. 

Greywater, of which each person produces 20 gallons to 40 gallons per day, works well for outdoor irrigation because it is available during the dry months, Russell said. If you plan to set up a greywater system, you’ll need to make sure you only pour eco-friendly soaps, shampoos and detergents down the drain since certain ingredients in conventional products will damage your plants. As of Jan. 1, California state codes changed so it's easier than ever now to install one of these systems.

A “Laundry to Landscape” system is the least expensive greywater system and is the only greywater system that doesn’t require a permit. With this system, used washing machine water is directed to the garden instead of the city sewer. If you’re washing dirty diapers or it’s during the rainy season, you can simply turn a lever to send the water down to the sewer. More complex greywater systems can filter and pump greywater throughout your garden. Others can combine with your drip irrigation system, irrigate uphill and add backup city water when needed.

Russell’s company WaterSprout has built rainwater and greywater systems in about a dozen homes on the Peninsula.

Using rainwater and greywater in your home and garden is an innovative way to conserve a precious resource: .

Interested in learning more about collecting rainwater and greywater? Check out cleanwatercomponents.com to see if they’re right for your home and garden.

Alexis Petru is a San Bruno resident who coordinates environmental programs for San Mateo County. Her column appears biweekly on Saturdays.

Do you collect rainwater or greywater to use in your home and garden, or are you considering it? Tell us in the comments.