Dear EarthTalk How can I make good use of the rainwater that runs down my roof and into my gutters?
— Brian Smith, Nashua, NH
For most of us, the rain that falls on our roof runs off into the ground or the sewer system. But if you’re motivated to save a little water and re-distribute it on your lawns or plants — or even use it for laundry, dishes or other interior needs — collecting rainwater from your gutters’ downspouts is a no-brainer.
If it’s allowed in your state, that is. Utah and parts of Washington State have antiquated but nonetheless tough laws banning anyone but owners of water rights from collecting rainwater flowing off privately owned rooftops. Such laws are rarely enforced, however, and one in Colorado was recently overturned.
According to John C. Davis, writing in E – The Environmental Magazine, just about any homeowner can collect rainwater, given that the roof and gutters do most of the work. And since an inch of rain falling on a 2,000-square-foot roof produces some 1,200 gallons of runoff, one can harvest enough to supply all the water needs of a family of four for about two weeks. Of course, most of us would only use rainwater to irrigate our lawn or garden, and there should be plenty to go around for doing that in all but the most drought stricken areas.
Plants and grass actually do better when fed rainwater instead of tap water, which is usually treated with softeners that actually inhibit plant growth. And, reports Davis, the lack of minerals in rainwater actually makes it more effective than tap water for shampooing or doing dishes. Using rainwater for plumbing uses can also extend the life of pipes and water heaters, since the salts added to tap water facilitate corrosion. Homeowners should set up a water purification system if they do plan to use rainwater for interior needs.
Beyond the benefits to individual homeowners, rainwater harvesting can also be good for the local community, as it reduces the erosion, flooding and pollution runoff associated with heavy rainfall, and lessens reliance on public water supplies, alleviating some of the burden on utilities. Given these benefits, some states, including even drought-prone Texas, subsidize residential rainwater collection systems.
Many varieties of rain barrel systems, starting at just $100, are available for home installation. A typical set-up is simply a rain barrel positioned under a gutter’s downspout. “The barrel is typically fitted with a spigot at its base to fill a watering can or attach a soaker hose (which bleeds out water all along its length, providing effortless drip irrigation), and a filter or screen at its top to prevent a buildup of leaves and other debris,” writes Davis. According to the U.S. Environmental Protection Agency, a single 100 gallon rain barrel can save up to 1,300 gallons of utility-provided water during the high demand summer months.
Handy homeowners can make their own water harvesting systems, but buying one pre-made is a lot easier. Most nurseries and garden centers offer a range of choices (as well as advice), but websites such as Aquabarrel, Clean Air Gardening and Rainxchange make it easy to order a system online.