A First for Rainwater Harvesting

July 6th, 2009 1:32pm PST

Posted By Elizabeth Cutright WE Mag

As I stated in my April 2009 editorial, due to increased interest in water conservation and sustainability, rainwater catchment is “poised to become not just an interesting side note, but also a powerful tool for water-strapped cities and states.”

(Divining Rods, Elements 2010)

Known as either rainwater catchment or harvesting, the process is quite simple and can be an easy first step for any water-strapped community searching for ways to supplement their current supplies. For example, in Los Angeles, CA, six projects capture 1.25 million gallons of water for every inch of rain, and there’s no reason those results can’t be replicated throughout the country.

Rainwater harvesting may be a no brainer, but it’s mostly been treated as a second-class citizen, something to ignore or marginalize in the face of (sometimes) flashier alternatives. But what rainwater catchment lacks in bells and whistles, it more than makes up for in terms of cost and ease of implementation. In Tucson, AZ, rainwater harvesting is suddenly in the spotlight. Tucson has just enacted the nation’s first municipal rainwater harvesting ordinance for commercial projects. Under this new ordinance, developers of new corporate or commercial buildings must design all landscape irrigation, so that 50% of the water used comes from a rainwater catchment system.

Tucson officials hope that the anticipated 12 inches of annual rainfall will supplement current municipal supplies (which come from wellwater and the Colorado River), starting next year. Like Santa Fe County, NM, the Tucson harvesting ordinance allows for a passive collection system (which mostly diverts run off from parking lots and roofs), as well as small harvesting combined with pumps and drip irrigation, but Tucson’s ordinance goes one step further by allowing for active harvesting as well. The Tucson city council has also approved an additional measure that requires new homes to have a plumbing system that would allow for separate drain lines so that a graywater system can be installed, and water from sinks, showers, and other appliances can be diverted to the homeowner’s irrigation system.

Because commercial projects are often a community’s largest water consumer, this ordinance should have a significant payoff. For example, the latest remodel at Tucson’s Target included a rainwater harvesting system that catches runoff from the parking lot and diverts it to towards small landscaped sections that include native plants and trees, which are designed to hold up to 15,000 cubic feet of water that would otherwise be lost to storm drains.

So what do you think? Why aren’t more communities requiring rainwater harvesting?  And, are ordinances the answer, or can public outreach use incentives to inspire individuals to implement their own catchment systems?

For more information on Tucson’s rainwater catchment ordinance, go to: http://www.tucsonaz.gov/water/harvesting.htm.

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