University of Tennessee at Knoxville
IN-26: Innovation C

The University of Tennessee has installed its first rainwater harvesting system to capture and reuse rainwater for indoor use in a building. This project was born out of the Facilities Services Stormwater Management department. This installation meets and exceeds requirements for the university’s Phase 2 Municipal Separate Storm Sewer System (MS4) permit, which states that stormwater from the 1st inch of a rainfall event must be captured or infiltrated rather than running off into the nearest stream or waterway. Typically, rainwater can be easily reused for irrigation needs. However, during many months of the year when irrigation is implemented less, the supply of harvested water can outweigh the demand. Using this water for indoor use in a student residence hall ensures that there is always a demand for the water!

Rain that falls onto the rooftops of Orange Hall and White Hall, new residence halls that opened in the Fall of 2016, is stored in a 35,000 gallon underground cistern. This rainwater travels through a vortex filter, a sand filter, a charcoal/carbon filter, a UV light filter, a bag filter, and is then stored in another tank where the water is treated with a chlorine drip. At this point, the process has removed impurities and prevented bacteria growth, and the water is technically clean enough to drink! However, it is only used for washing machine cold cycles, to flush toilets, and to irrigate campus landscape. One tank of rainwater provides enough water for 2,991 loads of laundry, 27,343 toilet flushes, or 31 days of irrigation.

While we’ve implemented rainwater catchment systems that collect water for reuse in landscape irrigation in other buildings across campus, Orange Hall’s system is the first to filter the water for domestic reuse at UT and in our utilities network, which presented the unique opportunity to work with the Knoxville Utility Board (KUB) on how to measure the building’s waste water impacts in adherence with the MS4 program. Currently, the building has four different meters measuring water – a meter to measure the water we purchase from KUB, a meter to measure the water that goes into the treatment system, a meter deduct that measures water that leaves the building for irrigation purposes, and a final meter that measures the treated water that goes to interior usage. This system, despite its complexities, allows us to accurately calculate the water that goes into the municipal sewer system.
Work is underway to install this same rainwater harvesting system in two residence halls currently under construction. Another installation is scheduled for next year. Green infrastructure is becoming more and more prevalent on UT campus!