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Rainwater reuse system reinforces sustainable goals at UW-River Falls

February 19, 2009

UW-River Falls students, faculty and staff may or may not have noticed the blue signs in the University Center bathrooms commenting on the gray water in the toilets. The signs-put up during J-Term-signal the recent success of the rainwater reuse system.

The rainwater reuse system is the first of its kind in a state of Wisconsin building, Mark Gillis, assistant supervisor of facilities maintenance, said.

The rainwater reuse system has begun to run functionally in the last month. The University Center opened two years ago, but the original design of the rainwater reuse system did not work.

The system had to be redesigned three times before it would start, according to Gillis.

The plumbing staff, engineer staff and Gillis had to maintain health and building codes while making the system self-sustaining and automatic.

The system is mainly up and running, but control issues like a pump that did not shut off one night and built up too much pressure are keeping it from operating around the clock.

“It’s a work in progress,” Gillis said. “[We] are still testing and adjusting it.”

The concept for the rainwater reuse system is simple, Gillis said.

Roof drains and drain tiles around the basement of the University Center collect rainwater into four 12,000 gallon tanks.

Capable of holding 48,000 gallons of water, the tanks are located under the front lawn by the bookstore. A submersible pump propels the water through a filter which rids the water of larger materials, like leaves, that could clog the system.

The water sits in the 500 gallon holding tank—the day tank—where it is treated with chlorine dioxide to kill any bacteria. A separate system, Halox, makes the chemicals to pump into the day tank. Two booster pumps build pressure to force the treated water through secondary filters, then up to the toilets and urinals throughout the building.

The day tank, submersible pump and filter were things added to make the system more reliable and user-friendly from a maintenance point of voice, Gillis said.

The water is treated with chemicals because the toilets and urinals could splash water.

A licensed plumber comes every day to test the water sample. 

“[The treated water] is supposed to be safe enough to drink,” Gillis said. “But I won’t be drinking it myself.”

Should the filter get plugged or the tanks run empty, the system automatically goes back to city water pressure. Anyone using the toilets or urinals would be oblivious to the switch.

UWRF students voted to pay an addition $1 million for the green concepts of the University Center and the rainwater reuse system is included in that cost, according to Cara Rubis, assistant director of the University Center.

Operating costs for the system are unknown because it does not run all the time yet.

“It is going to [cost] more than using the city water, I can tell you that,” Gillis said.

The University Center pays $500 per month for water charges, not including a sewer charge for flushing. The water charges amount should decrease, but the cost of maintenance is a factor as well.

“In doing things like this, it’s hard to say things in today’s dollars and cents,” Director of Facilities Michael Stifter said. “I have no doubt what we have learned over the past two years [in getting the system operational] is something we can share with others.”

Gov. James Doyle selected the University—along with three other UW campuses—to become energy self-sufficient by the year 2012, according to a September 2006 UWRF press release.

The rainwater reuse system is part of the University’s efforts to become sustainable.

The system cuts down on the energy-associated with greenhouse gas-that would normally be used to pump clean water from the aquifer. Also, it makes use of water that would otherwise be shipped to the ocean via streams and rivers, according to Director of the St. Croix Institute for Sustainable Community Development Kelly Cain.

“[Using] good clean water to flush stuff down a toilet is not a good way to use valuable water,” Cain said. “We live in the Saudi Arabia of water around here. We don’t have a sense of how valuable water is in the world… Over the long haul, as water gets more valuable, I suspect our system will pay off, besides just doing the right thing.”

Elementary education senior Meghan Moynihan, 22, has been a building manager for the University Center since May. Also a campus tour guide, she said she thinks the water system is a great way to promote being green.

“As part of our [campus] tours we do mention the green factor,” Moynihan said. “Prospective students and families get a kick out of it.”