How Does a Rain Barrel Work?

Rain barrels can collect hundreds of gallons of water for you to use in your garden.
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Every time an inch of rain hits a 1,000-square foot roof, 620 gallons of water rushes through gutters and downspouts. During heavy rain, this can cause sewage overflow and flooding. Those barrels under your neighbor's eaves actually help reduce these problems, even if you find them tacky. Understanding the purpose of rain barrels may inspire you to set up some yourself.

Rain Barrel Operation

Rain barrels can vary in set up and style, but their overall design and operation is the same.

The typical rain barrel, which holds about 55 gallons, is made of food-grade plastic or is an old wine barrel. A hole is cut in the top of the barrel, and the downspout from a gutter is redirected so rain water collects in it. When it rains, the barrel fills up with water.

Two smaller holes are cut into the side of the barrel -- one near the top and one near the bottom. The top one serves as an overflow outlet for times when the barrel fills up. Many rain barrel owners choose to direct this overflow into their lawn with a length of hose. The bottom hole has an attached hose bib and allows the barrel owner to access the water in the barrel.

How This Helps

If several hundred gallons of water rush into the sewage system from a single 1,000-square-foot roof, imagine how much water flows into it from a typical neighborhood.

In a natural system, the water hits the ground, filters through the soil and percolates back into underground reservoirs, and then slowly re-enters waterways. In a city, paved streets, parking lots and driveways create a block in this natural cycle. Instead of slowly finding its way back to streams and rivers, the rain water quickly runs off into waterways or washes into sewage systems. This sudden flow not only washes contaminants from roads into the water, but it also increases the risk of flooding. Overwhelmed sewage systems spill waste into rivers. Rain barrels help reduce these problems by keeping some of the water from rushing back into the system.

Water Conservation Benefits

Using water from rain barrels helps conserve water. Rather than using water from the municipal utility to water the lawn or wash the car during dry periods, the person with a rain barrel can instead use stored rainwater. The usage may not make a big dent in lowering water bills, but conserving fresh water is an important environmental issue, especially as weather patterns change around the globe.

Using the Water

Rain barrel water should be used only in the garden and never for drinking. Some concerns have been raised about the safety of using rain barrel water on vegetable gardens because chemicals leaching from roofing tiles can be taken up by the plants and animal waste can get into the water. To reduce the likelihood of any contamination, reduce rain barrel water use on edibles once fruit begins to set and before harvest time. Also take steps to reduce mosquito growth in rain water barrels.

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