NMSU Gray Water Study Covers Cooling, Too

In an effort to save millions of gallons of water each year, researchers at New Mexico State University are working on turning once unusable wastewater into water suitable for home landscape irrigation, according to a March 17 press release.

The research aims to not only reduce the amount of water consumed every year but to also make it easier for homes to grow plants that clean the air and reduce cooling costs. A 1,500-square-foot grass lawn produces enough oxygen for a family of four to breath in a year. A large shade tree can significantly reduce the energy needed to cool a home in the summer.

“We are running out of water in New Mexico,” said Ryan Goss, an assistant professor at NMSU’s Department of Plant and Environmental Sciences in the College of Agricultural, Consumer and Environmental Sciences. He’s also a researcher on the project. “Water is clearly our most valuable resource and anything we can do to help make our water supply more sustainable is important.”

Goss’ project involves a public/private partnership with Aquaverde, Inc. The company has created a water pump and filtering system that’s easily attached to a home’s existing wastewater line. As part of the system, sensors are placed throughout the house to ensure the pump catches only gray water – water from bathroom sinks, showers, and washing machines. Water from the kitchen sink and toilets is considered black water and not pumped into the system. Once the gray water is intercepted, it is sent through a series of filters and exposed to ultra violent light to eliminate harmful bacteria. Once processed, the water is available for landscape irrigation.

“This system has many unique engineering aspects that make it immediately useful to existing and future households,” Goss said. “Other systems require additional plumbing and therefore are not useful for retrofitting homes.”

A family of four typically goes through as much as 100 gallons of water a day. Goss wants to find out how much gray water that typical family produces and to test to see how effective the system’s filters are at removing harmful substances in the water. Goss said phosphorous and similar chemicals in detergents that make it through the cleaning system are actually beneficial to landscaping plants.

The system is currently installed at NMSU’s Fabian Garcia Science Center family residence where it will be used to irrigate a portion of the adjacent university arboretum. Currently the system fits inside a small, inconspicuous shed outside of the house. Future models may be small enough to fit inside a decorative landscape rock.

Because of New Mexico water regulations, the water from the system can only be delivered by a subsurface, drip irrigation system. Goss’ group will install drip irrigation at the location over the spring semester.

This research coincides with NMSU’s Year of Sustainability. During 2009, the university’s goal is to highlight and encourage programs and research that promote an environmentally, economically and socially sustainable future.