Saving Water, Saving Money

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Susie P. Gonzalez
Mar. 26, 2012

Saving Water, Saving Money

Trinity University's Center for the Sciences and Innovation using water condensate to flush toilets

SAN ANTONIO - The idea was sheer genius. Instead of letting water collected from massive air conditioning units literally go down the drain, use it to flush toilets. Thanks to changes in a 2006 building code, Trinity University is doing just that in the Center for the Sciences and Innovation (CSI), and thus saving both water and money.

Trinity already was saving an estimated 21,000 gallons every month by installing low-flow toilets in the new building, but converting to a system that captures and treats water condensate from the A/C equipment for toilet flushing will conserve even more. How much more won't be known until flow meters can be mounted on the equipment and calibrated.

In the meantime, students of Diana Glawe, associate professor of engineering science, are learning from the professionals who designed the CSI water condensate system that pipes water from the fifth floor of the CSI to the basement, where it is stored in six 1,000-gallon tanks, treated with ozone, and pumped to the building's 33 toilets and 12 urinals.

"It's been helpful to see the behind-the-scenes aspect," said Courtny Edge, a sophomore engineering science major from Portland, Texas, who is considering an environmental science minor.

"This system makes a lot of sense," said Eshan Jayamanne, also a sophomore engineering science major from Sri Lanka.

During a tour of the system, Steve Mechler, whose San Antonio firm represents plumbing, HVAC, and general contracting manufacturers, commended Trinity for conserving water. "We are always looking for voluntary conservation, but what Trinity has done with this project shows that it cares about the environment," Mechler said.

Five years ago, rainwater was the conservation buzzword, he said. However, rain falling onto rooftops and into tanks was susceptible to picking up debris, and as any San Antonian knows, rainfall is not reliable. All structures with air conditioning systems create condensate, but before the building code changed in 2006, that water could only be used for landscaping purposes. When the code was rewritten, treating microbes in the condensate would be the next challenge, Mechler said. He listed chlorine and ultraviolet light as two possible but expensive options. The system he recommended for Trinity relies on ozone to "kill everything in the water."  The ozone is not considered a health hazard, since it reverts to oxygen after 17 minutes of exposure to air, he said. As a precaution, safety equipment has been added to Trinity's ozone treatment system.

The system's water savings is projected to double when construction of the CSI is completed in 2014, said John Greene, director of Campus Planning and Sustainability at Trinity. Greene said the CSI already is a registered LEED project with the U.S. Green Building Council, which signifies that the building was designed and built using strategies aimed at achieving high performance in key areas of human and environmental health, water savings, and energy efficiency, among others. 

The CSI is the most ambitious construction project in Trinity's history as it anticipates the needs of students in the 21st century.