Beyond Showerheads—Fixing Leaky Diverters – GreenBuildingAdvisor

By Jon Harrod | July 18, 2025

As a fledgling home-performance contractor in the early 2000s, I got a lot of satisfaction from finding and replacing high-flow showerheads. Many of these older fixtures had flow rates of 3 to 5 gallons per minute (gpm), well above the 2.5 gpm federal limit that went into effect in 1994. Installing high-performance showerheads was and is a low-cost, high-impact improvement that saves both water and energy.

But while I was measuring showerhead flows with a pitcher and stopwatch, I may have been missing an opportunity right at my feet. In my new job at Taitem Engineering, I came across a 2011 study by my colleague Betsy Jenkins Parrington, PE, titled “Leaking Shower Diverters: An Overlooked Energy Conservation Measure.” The study was originally published in the now-defunct Home Energy Magazine and is now available as a tech tip on the New York State Energy Research and Development Authority (NYSERDA) website.

Diverters are the valves found in combination tub/shower units; they direct water either up toward the showerhead or out the spout. When water leaks out of the tub spout during a shower, it flows directly into the drain, and all the energy that went into pumping, treating, and heating that water is wasted.

According to Jenkins Parrington, now vice president of Taitem, the inspiration for the study came from a 2010 site visit to an apartment complex in NYC. The visit was performed by Evan Hallas, a senior energy analyst at Taitem with whom I now share an office. Hallas observed three shower diverters with leak rates of 1.5, 4.0, and 6.0 gallons per minute (gpm). In his report, Hallas noted that, according to the building superintendent, “almost all of the bath faucets have this issue.” Diverter leakage was not identified in an earlier energy audit by another company.

Diverter leaks in existing buildings

Jenkins Parrington’s study, funded through…