Tucson to harvest rainwater

TUCSON, Ariz. | Long dependent on well water and supplies sent hundreds of miles by canal from the Colorado River, this desert city will soon harvest some of its 12 inches of annual rainfall to help bolster its water resources.

Under the nation’s first municipal rainwater-harvesting ordinance for commercial projects, Tucson developers building new business, corporate or commercial structures will have to supply half of the water needed for landscaping from harvested rainwater starting next year.

Already, the idea has become so popular that at least a half-dozen other Arizona communities are looking to emulate Tucson’s approach.

“What we learned, frankly, is that we’re wasting a lot of water. It’s been our tradition here to shove it into the streets and get rid of it as soon as possible,” said David Pittman, southern Arizona director of the Arizona Builders’ Alliance.

Rainwater harvesting is also catching on nationwide, with Georgia, Colorado and other states legislating to allow or expand use of various types.

From Portland, Ore., and Seattle to San Francisco and Austin, Texas, voluntary rainwater harvesting is irrigating plants or being used in other ways instead of merely falling onto roofs, parking lots or pavement and being drained into sewers as wastewater.

“There’s only so much water. Unfortunately, Americans are terribly, terribly wasteful with water, and we’re running out,” said Tim Pope, who builds harvesting systems in the San Juan Islands near Seattle and heads the American Rainwater Catchment Systems Association.

Water supplies from the Colorado River are likely to diminish from the increasing demands from other states in the West. And groundwater is carefully managed to prevent overpumping the water that supplies the 1 million people who live in growing metropolitan Tucson.

That makes conservation and rainwater harvesting all the more important.

Landscaping needs account for about 40 percent of water use in commercial development and about 45 percent of household water consumption, “so there is huge potential,” said Tucson City Council member Rodney Glassman, who spearheaded efforts to achieve the ordinance.

Rainwater harvesting holds particular appeal in the desert because of the combination of drought conditions and limited sources.

Mr. Glassman, a first-term council member, campaigned in 2007 for rainwater harvesting in new commercial development and for systems that capture water from washing and bathing in new homes.

Last year, Tucson’s water utility delivered more than 131,000 acre-feet of water, including 26,000 acre-feet of reclaimed wastewater. According to Mr. Glassman, experts estimate more than 185,000 acre-feet of rainfall is available per year.

An acre-foot is about 326,000 gallons, enough to cover an acre a foot deep or supply about two households with water for a year.