Would you water your garden with what goes down your shower drain or out your washing machine? In Tucson, Arizona, and an increasing number of water-starved western cities, more and more residents are saying yes.

If you’ve never contemplated what happens to the water that gets you or your clothes clean, you’re far from alone. But for cities and environmentalists trying to head off the growing threat of drought and rising water costs, so-called graywater — differentiating it from the “black water” that goes down the toilet — is getting a lot more attention. A decade ago, Tucson, which has about a million residents in its metro area and is a liberal and environmentally conscious oasis in a red state, convinced Arizona legislators to make it legal for homeowners to irrigate their trees and plants with the water that was going down their drains or out of their washing machines without a permit. Now, graywater use is not only legal in Tucson, and indeed the rest of Arizona, but promoted, and, in some cases, required. In 2007, the state rolled out a tax credit of up to $1,000 for homeowners who install graywater systems. Last year, a law — believed to be the country’s first — went into effect in Tucson that requires builders to include graywater plumbing in new construction.

(Article source: Time article series on Intelligent Cities. Read full article here…)