UC calculator drives water efficiency in homes

Water runs our lives. Yet most of us take water for granted – we turn on the faucet and water flows. But a lot goes on behind the scenes, and how we use water governs how we design water delivery systems.

Researchers at the University of Cincinnati recently developed a water demand calculator, a tool that calculates the expected peak flow rate of water in modern residential buildings. When applied commercially, the calculator can provide significant water and energy savings.

The International Association of Plumbing and Mechanical Officials just incorporated the calculator into its Uniform Plumbing Code, making it part of universal practice for constructing residential buildings. Contractors and engineers can use this tool to size a building’s premise plumbing system – pipes, pumps, meters, heaters, softeners – in anything from a family home to a high-rise apartment complex. 

In a world with growing populations and stressed water sources, this tool can have great impacts on a society’s sustainability and the environment’s health. The calculator is an example of innovation at work, a pillar of UC’s strategic direction, Next Lives Here.

Historically, when engineers design a building’s water distribution system, they use the Hunter’s design curve, a water demand estimation tool first established in 1940. Not surprisingly, people’s water consumption habits, along with water fixture performance, have dramatically changed since then.

“Per capita water use in the U.S. has been dropping for the last two decades, but you couldn’t really capture that trend in the building codes that dated back to World War II,” said UC civil engineering professor Steven Buchberger, Ph.D., who led the project. 

After several years of collecting and analyzing data on these houses’ water uses, Omaghomi developed the water demand calculator. With this calculator, contractors finally have a modern method for sizing premise plumbing systems.

Contractors simply plug in the house’s number of water fixtures and each fixture’s flow rate, and the calculator will estimate the 99^th percentile demand flow, or the flow rate that is exceeded only one percent of the time.

“The water demand calculator provides codified justification for downsizing,” said Buchberger, who acknowledged that builders knew they were oversizing their pipes but didn’t have enough quantifiable data to change their practices. “This calculator is the regulatory greenlight.”

Now UC environmental engineering master’s student Chris Douglas is taking the water demand calculator and applying it to multifamily buildings, like apartment complexes and high-rises. Specifically, Douglas is studying how to design more efficient water systems within the constraints of older water meters. 

By testing the scalability of the water demand calculator, Douglas is paving the way for more efficient construction practices.

“The water demand calculator provides a scalable framework that can help size water supply systems in cities of the future,” said Buchberger. “That’s where you’re going to see widespread application and a very significant return on investment.”

As populations grow, water challenges inevitably surface. Tools like UC’s water demand calculator can help manage this precious resource, leading to a healthier planet and more sustainable future. 

Featured image at top: UC graduate student Chris Douglas explains the water demand calculator. Photo/Corrie Stookey/CEAS Marketing