Harvesting rain for a dry day

By February 9, 2007Uncategorized

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.

The water caught in the barrels and tanks would be stored in the aquifer if the roofs and concrete or asphalt surfaces weren’t funneling it into storm drains and shooting it into fragile creekbeds. The result is erosion and creeks that go dry for months, disrupting habitats and leaving salmon and other species to die in dwindling pools.

“These are all predictable effects of what we are doing,” Bouley says.

Putting barrels under the gutters of every home is not going to fix that problem entirely. It’s not even going to save people any money. Water is artificially cheap, Bouley says, and the barrels and hoses cost money.

But plugging into the natural rhythms of rain and drought might raise people’s water consciousness, she says. “It will enlighten you to the cycle of water.”

Dolman tells people to think of their rainfall harvesting systems as a kind of “savings account.

“Every winter the planet gives you an allowance,” he says.

People have to think about how much allowance they need. With 100 square feet of roof surface “for every one inch of water, you’ll get about 55 gallons,” Dolman says.

Gardeners can tie in an efficient drip-water system and plant low-water-use vegetation, making the water last across the dry months. Dolman calls it “balancing the water budget.

“There’s nothing here that’s new, except you’re filling your tank off the roof instead of pumping it out of the ground.”

Why more people aren’t taking advantage of their runoff isn’t so much a mystery as a source of frustration for Dolman and Bouley. Many people don’t think beyond the faucet, ignoring the effect of habitat destruction, erosion and pollution.┬áRain and water only enter the consciousness when there’s too much or too little. Floods and severe droughts get attention. Drying creeks escape notice.

Catching water is catching on in other areas, Dolman says. He points to New Mexico, Texas and Hawaii as sources of innovation. With water in varying stages of crisis across the state, he can’t understand why it isn’t happening here. “California is kind of behind the curve on this.”

“We’re a little bit in denial,” observes Bouley, who lives across the street from a home where a mudslide caused extensive damage. Artificially altered landscapes can have disastrous consequences.

People shouldn’t wait for a drought or a flood to start thinking of their place in the watershed, Bouley points out. She tries to look at the landscape “from ridge to creekbed, including the people in between.”

The driveways, roofs and roads are major alterations. The barrels behind her shed, and the driveway that lets water soak in instead of sheeting off, are a small kind of mitigation. If more people had more barrels, and took the ethic they learned into their homes, the effect could be big.

“We could have a cumulative effect for the best,” she says. “Or for the worst.”