CSU testing graywater irrigation

FORT COLLINS - To better manage water resources, states like Colorado may soon rely heavily on graywater - the non-potable water that flows from showers, bathroom sinks and washing machines.

Using graywater to fill up toilets and irrigate landscapes could cut down household water use by around half, according to researchers at Colorado State University's Urban Water Center.

But graywater, those researchers add, is still a big unknown.

They say little research has been done on any possible negative effects if used outdoors.

That's why CSU professors Sybil Sharvelle and Larry Roesner just started a three-year research project aimed at studying graywater irrigation.

"We are assessing plant health, soil chemistry and microorganisms in graywater irrigation areas and comparing the findings with samples taken in the same yard where similar vegetation exists that is irrigated with city water," Sharvelle said.

They're looking at graywater systems in California, Arizona, Texas, and Colorado.

As part of the project, the researchers want to find out if any household products make graywater irrigation harmful to either humans or plants.

Their findings could help lawmakers better regulate the use of this potentially invaluable water management tool.

Regulations currently exist in California and Arizona, but not Colorado.

The CSU team is also looking into how to best treat and capture graywater.

For treatment, they've constructed a wetlands treatment system for graywater at the Atmospheric Chemistry building on the Foothills campus.

To test a capture system, they plan to install specialized plumbing in one wing of a new residence hall on the CSU campus.

That system would separate graywater from blackwater, which comes from toilets and kitchen sinks.