Burlingame asks: How green is gray water?

BURLINGAME — The merciless drought parching California is forcing people to confront scary questions about the state’s water supply — and search for answers.

On Wednesday, city leaders in Burlingame will host a forum on two emerging methods of water conservation titled “The Pros and Cons of Gray Water and Rainwater.” Tom Bressan, owner of the Urban Farmer Store and an expert in water-friendly landscaping, will lead the discussion.

Gray water systems recycle household water from sinks, showers and washing machines for other uses, such as watering gardens or flushing toilets. Capturing rain and then releasing it later allows more water to seep into the ground rather than flow into storm drains.

California has made great strides in water conservation since the last major drought in the 1970s, Bressan said in a phone interview. But population growth and the possibility of climate change drying out the Sierra Nevada snowpack mean Californians will need to go even further.

“We have to develop things that use water again and again,” Bressan said. “Anything we can do to slow water from becoming saltwater is important — all water eventually makes its way to the ocean, and then it’s practically useless to us.”

The state currently places restrictions on the use of gray water to protect public safety. Water from the kitchen sink, for instance, may contain harmful bacteria.

But recycling gray water from a washing machine to irrigate plants is safe and relatively easy, Bressan said, so long as you use “biocompatible,” or nontoxic, detergent. Water that’s been treated with bleach or any other chemical must be sent into the sewer system to avoid contaminating groundwater.

The San Francisco Public Utilities Commission, with Bressan’s help, has established a “Laundry-to-Landscape” program that includes rebates and technical assistance for homeowners. For more information, visit http://sfwater.org and search for “gray water.”

The benefits of capturing rainwater are more general than specific, Bressan said. So much rain falls during the Bay Area’s winter storms that the ground quickly becomes saturated, sending water streaming into the street and down the drain. Catching the water in 60-gallon or larger barrels, or designing landscapes with depressions known as swales, reduces runoff. Releasing it between storms cuts down on water consumption in the garden and replenishes underground reservoirs.

“In my little way, I can recharge San Francisco’s aquifer by about 25,000 gallons a year,” Bressan said of the system he’s set up in his own home. “When a lot of people do that, it adds up.”

Burlingame Vice Mayor Terry Nagel said city officials hope Wednesday’s event will spark ideas for improving the city’s approach to water conservation.

“With water becoming more scarce, people are taking a closer look at some alternative water systems,” she said. “If we were smarter about how we use our water, we wouldn’t depend so much on rain and those infrastructure projects that are so expensive, like dams.”

Contact Aaron Kinney at 650-348-4357. Follow him at Twitter.com/kinneytimes.