When I install a low-flow toilet, I use less water each time I flush. In the arid West, this is a good thing, right? Maybe. Maybe not.
In Albuquerque, essentially every gallon I flush, after treatment at our sewage plant, ends up in the river, available for downstream users. It’s called “return flow credit”, and serves not only as a debit on the water accounting side wherever the water is withdrawn, but also as a credit in the river.
Such is the counterintuitive being faced in Las Vegas now as “graywater” systems are being discussed, and being opposed by the very people you might think would want to encourage such efficiencies. From the Las Vegas Sun:
The Southern Nevada Water Authority wants that system preserved because it allows Las Vegas to consume more than its annual 300,000-acre-foot allotment from the Colorado River. Water returned to the lake converts to credits that the Water Authority can use to pump more water from the lake.
But some homeowners, builders and environmentalists watching this continuous loop wonder: Why not shorten the distance water travels by allowing homes to keep and recycle the water they use — what’s known as graywater? Water from sinks, showers and washing machines could be reused to more efficiently and cheaply water lawns or other landscaping, they say….
The water authority, after studying the idea, decided this year to make it official policy to oppose it.