Paola Bouley unscrews the lid on the fifth in a line of bulging plastic barrels behind the storage shed and leans forward, peering into its murky depth. “This is last year’s water,” she says.
More accurately, it’s last year’s rain. Bouley, a biologist for the Salmon Protection and Watershed Network, is one of a small – and she hopes growing – number of homeowners who are harvesting rain from roof gutters and using it to water plants, prevent erosion and spread a new water consciousness tied to natural cycles.
The barrels positioned behind the shed and just past the rain-grabbing permeable driveway catch a modest 450 gallons of water, a fraction of the 5,500 gallons that flows off the 264-square-foot roof in an average year. But it is enough water to irrigate her fruit trees and help establish an array of native plants she is cultivating in the yard of her Fairfax home.
“We catch way more water than we can use,” says Bouley, who cites claims that one-third of Marin residential water use will go to landscaping in the summer months.
The system is simple. The rain runs off the roof and into the rain gutter. It then pours through a window screen filter into the first of the barrels. When that barrel fills, it siphons into the next. The process goes on until all five barrels are filled, and Bouley has enough water to keep her plants and trees thriving. Bouley assembled the system with her husband. There is no hydraulic sophistication. “I’m not a tinkerer person,” she admits.
That’s the beauty of “rainfall harvesting,” says Brock Dolman, a sustainable design instructor at the Occidental Arts and Ecology Center. Nobody has to be an expert on anything.
And they have most of the equipment already. They’re just not using it. “They already have a roof,” Dolman says. “They already have downspouts. Getting water into a tank and pre-filtering it can be a pretty simple process.
But few people are taking advantage of that simplicity. Bouley and Dolman were part of the team that built a rainwater harvesting system at Lagunitas School. The system catches 30,000 gallons off the school’s playground structure and saves it for use in an organic garden.
That idea can easily be scaled down. Bouley estimates that rooftops catch 85 million gallons in the San Geronimo Valley alone. The technology is certainly nothing new. Rainwater has been stored in cisterns since ancient times. But it’s older than that, Bouley says. It’s how nature works, given the chance.