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Catching Raindrops

You can save money and conserve water simply by capturing the rain that rolls off your roof.

By Eileen Mattei

Rain barrels and cisterns are no longer merely nostalgia-inducing curiosities. As demand for Texas water surges, straining reservoirs, draining aquifers and reducing flowing springs, water conservation has become a vital issue.

Effective rainwater capture systems called guzzlers have been used for years at Black Gap and Elephant Mountain Wildlife Management Areas, for example, to support wildlife. Now, capturing rainwater for home garden and wildlife use is gaining more practitioners thanks, in part, to TAMU Cooperative Extension agents who are promoting rainwater use.

Rainwater harvesting involves catching, storing and distributing rainwater to use for wildlife and landscaping. Storm runoff - the rain sheeting off your roof and driveway heading for storm sewers - is an asset you can capture and use. In the process, you help reduce flooding and stream erosion.

"We are stewards of that raindrop wherever it lands. If we don't capture it, it goes downstream," says Menard County agent Billy Kniffen, a leading rainwater harvesting advocate. Because landscape irrigation grabs 30 to 50 percent of urban water usage, harvesting rainwater reduces both the pressure on a limited resource and your water bill. He points out that Santa Fe, New Mexico, now requires houses larger than 2,500 square feet to install a rainwater collection system.

To begin rainwater harvesting, look at the slope of your land and how water drains off it, the plant and soil types, and your catchment area, which usually means your roof, although it could be a driveway or tin panels as well. One inch of rain on 1,000 square feet of roof yields about 600 gallons of high quality water, which adds up in a hurry. (A house's square footage roughly equals its roof size.) Existing gutters and downspouts help channel water to containers.

If your soil is sandy or caliche, rain dripping from the roof or flowing out a downspout can water a small landscape area enclosed by a shallow berm. Otherwise, to prevent damage to your foundation, rainwater can either be captured in containers or channeled through a ditch or by downspout extensions to a holding area or a rain garden at least 10 feet from the house. A rain garden is a level but slightly depressed area edged by a 5-to-8-inch-high berm that holds rainwater for less than 24 hours while it slowly infiltrates the ground. It is usually rimmed with native plants.

To make a small-scale, simple rain barrel, start with a new 32-gallon plastic garbage can with a lid.

  1. Use a 3/4-inch hole saw to cut a hole about 4 inches above the bottom of the can.
  2. Insert a half-inch plastic or metal faucet backed with a flat washer and a rubber washer.
  3. Secure the faucet from the inside with a rubber washer, a flat washer and then a 1/2-inch PVC threaded coupling (or metal washer and thin nut).
  4. On the lid, cut out a 4-inch by 4-inch opening.
  5. Use silicone caulk to attach a 5-inch by 5-inch piece of fine mesh nylon screening from the inside. The screen keeps debris and mosquitoes out.
  6. Cut 2-inch hole for overflow near the top and attach the nylon screening. Position the screen of the barrel beneath the junction of two eaves of a gutterless roof, at a gutter end or under a shortened downspout. You can connect several barrels together at their overflow pipes. Attach a hose to the faucet and run it to a landscaped area or, with a drip emitter attached, to a pet or wildlife watering pan.

Texas Master Gardeners and Master Naturalists present rainwater harvesting workshops on simple and complex systems with precise tables for determining your needs and options. For more information, visit <rainwaterharvesting.tamu.edu> or <www.twdb.state.tx.us>.

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