Saving Rain
The Joys and Challenges of Catchment Systems
By Rachel Foster

When I visited the U.K. last spring, much of the country was in a prolonged drought and under a comprehensive hosepipe ban. Water barrels beneath downspouts were enjoying new-found popularity. Britain differs from the Willamette Valley in that it may rain a little at just about any time. With a whole roof to collect rainwater, it doesn't take much to put a few gallons in the "water butt," and occasional sprinkles were allowing ingenious Brits to get a food garden started or even to water the lawn.
Jan Spencer
When I returned to Eugene I contacted Tammie Stark, a local rainwater management professional who consults with people who want to install water collection systems at their homes. I wanted to talk to her about the practicalities of saving rainwater here in the valley, where it may not rain at all for many months. I've often thought about harvesting rainwater for myself, but my enthusiasm flags when I realize how large a tank I would need to make even a dent in my summer water use. There is, however, plenty of local interest in the topic, particularly among the permaculture community.
As Stark says, "Using a rainwater harvesting system helps mitigate the negative effects of stormwater, recharges groundwater and decreases stress on the municipal water treatment facilities. And harvesting rainwater enhances one's sense of place." People find satisfaction in reducing their summer use of city water and the energy it takes to provide it. If you live in the country, you can supplement a well and in some instances provide higher quality water for growing vegetables and little seedlings.
Stark visits a number of rainwater collections sites to test water quality for EWEB. One of those sites is Jan Spencer's home garden. Spencer has turned his River Road area property into "an evolving suburban conversion to a sustainable system." He has two 1,600 gallon polyethylene tanks he got inexpensively from a farmer. Water is directed to the tanks via a gutter system, and overflow pipes lead to a number of ponds, from which excess water dissipates into the ground. The tanks fit neatly in Spencer's narrow, shaded side yard. Shade for these tanks is essential to keep the water at a usable temperature. "Whatever color the tank," Stark tells me, "the temperature in full sun will get up to 86 degrees, which is too hot for watering plants."
Spencer's tanks are black, which keeps out light and prevents algal growth. Each has a vertical clear plastic tube attached that shows the water level. This is a gravity fed system: with one valve open, water flows to a number of pickle barrels placed around the garden into which Spencer dunks watering cans to deliver water directly to individual plants. The tanks also feed a drip irrigation system (half-inch plastic pipe delivers water to open ended half-inch irrigation lines -- there's not enough pressure for emitters) for "permanent" plants like blueberries. There is also an open hose with a shut-off valve for hand watering. Since the tanks top out around 4 feet, Jan has only to raise the hose a little to stop the flow!
The roof on Spencer's one-story house has an area between 1,700 and 1,800 square feet. An inch of rain delivers roughly 550 gallons of water. That means the tanks could fill several times over in the course of a winter, but Spencer can save only as much as the tanks' combined capacity of 3,200 gallons. "Does this fill my agricultural needs? Not completely," he says. "I need 3,000 or 4,000 gallons for a whole summer for the food garden in back, but I also have the front garden." It's mostly a large, thirsty berry patch. The back yard will soon house a third tank, shaded by a grape arbor.
Issues that rainwater harvesters must address include directing overflow, possible toxicity or debris from roofing material and an adequate foundation for the tanks. Insects and other critters must be excluded, too. Space for the tanks may not be such a great obstacle. I estimated Spencer's tanks to be roughly 5 feet wide and 10 feet long. Set on blocks, the highest point of the two tanks is about 4 feet. One or two tanks of these dimensions might easily fit in the back of a carport. Or underneath my deck.
Please visit Tammie Stark's website: www.eugenerainwater.com Also visit Jan Spencer's website: www.efn.org/~spencerj/ Heiko Koester and Jude Hobbs will offer "A Practical Workshop on Urban Water Catchment" Nov.18 at the Dharmalya Center, Eugene. For more information: 485-7245 or hobbsj@efn.org