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Noah Garrison’s Blog

They're giving away free water: capturing rain from our rooftops

Noah Garrison

Posted February 14, 2012

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When I boarded my plane Monday morning in Portland, Oregon it was (not surprisingly) raining.  When I landed in Los Angeles a few hours later, it was raining.   It was raining most places I flew over in between the two cities.  And it rained in Nevada, Arizona, and a good chunk of the Midwest.  South through Texas and Louisiana, which saw up to four inches of rain.  East into Georgia.  Rain fell over Portland and Oakland, Medford and Modesto, Reno and Plano, and Corpus Christi and Baton Rouge.  Most of that water ended up funneled into a storm drain and dumped into the nearest river, lake, or beach.  Which is a shame, because the opportunities for capturing that water to increase local water supplies are tremendous.

NRDC has released a report titled “Capturing Rainwater from Rooftops: An Efficient Water Resource Management Strategy that Increases Supply and Reduces Pollution.”  The report demonstrates that at a time when many communities across the country are facing increasing risks of water shortages from, among other causes, prolonged periods of drought and the effects of global warming, capturing rainwater from rooftops can be a simple, cost-effective way to supply water for non-potable uses such as lawn watering and toilet flushing.  It profiles eight U.S. Cities, and shows that even under a conservative set of assumptions, each city could capture hundreds of millions to billions of gallons of rainwater from rooftops each year, equivalent to the total annual water use of tens to hundreds of thousands of residents.  And by using the rainwater, rather than allowing it to run off, pick up pollutants like trash, animal waste, metals, oils, and bacteria from paved surfaces, and then dump them in the nearest water body, the practice not only reduces strain on existing water supplies, but also reduces a leading cause of surface water pollution.

There’s a wide variety to the lengths cities and states are going to in order to promote or authorize (or in some cases unfortunately, prohibit) the use of captured rainwater, particularly for indoor non-potable purposes, as I’ve talked about previously here.  Some states, such as California, that have an obvious need for the added water supply are still struggling to expand use of the practice.  Others locations, such as Tucson, Arizona, now actually require all commercial development to provide 50 percent of their landscape irrigation water from harvested rainwater.  As changes in water availability increase pressure on urban users, farms, cities, counties, and states to meet their water needs, it should be clear that anywhere there is a rooftop, there is an opportunity to increase water supplies.   And it’d be nice to look down on all those rooftops the next time I’m in the air on a rainy day, and know that they were really only a quick stop for the rain on its way into someone’s storage tank.

EPA - Santa Monica Rainbarrell.JPG

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