A murky plan for graywater

Wednesday, April 15, 2009 | 2:10 a.m.

A bill that would have allowed the recycling of residential graywater — the waste water from sinks, tubs and washing machines — died in the Legislature last week.

Some states and some other countries allow people to install plumbing that captures graywater for use in sprinklers and irrigation systems. Graywater recycling has found support among some environmentalists, who say it is a good way to conserve water and reduce water bills.

But such systems have been controversial. The proposal in the Legislature ran into stiff opposition from the Southern Nevada Water Authority, which expressed concerns about a number of serious issues — from the cleanliness of graywater to what it could do to Southern Nevada’s water supply.

“The quality of graywater is very, very, very low,” water authority spokesman Bronson Mack said. “Just look at the back of your shampoo bottle or what’s in laundry detergent.”

Beyond that, as Alexandra Berzon reported in Monday’s Las Vegas Sun, graywater plays an important role in the water authority’s plans.

In the Las Vegas Valley, used indoor water runs into the sewer system, is treated and then is returned to Lake Mead through the Las Vegas Wash. Under federal regulations, the authority receives 300,000 acre-feet of water from the lake each year, but it is able to draw more water in exchange for returning water to the lake. Through such return-flow credits and water reuse programs, the authority has been able to take 70 percent more water than its annual allocation.

Mack said the Legislature’s graywater recycling proposal “doesn’t help us stretch the existing allocation out of the river,” and he is correct. The water authority has used return-flow credits to keep up with Southern Nevada’s needs. The proposal in the Legislature failed to take that into account, and that could have had dire consequences, leaving Las Vegas high and dry.