All toilets and most showerheads today meet the federal water-efficiency standards, but not all of these products perform satisfactorily. With toilets and showerheads, we include products that meet or exceed WaterSense standards, which includes performance requirements—although we go beyond WaterSense where there are issues not adequately addressed by the program. We also look for other products that conserve potable water, such as rainwater catchment and graywater recovery and reuse systems.
The Shower Manager is a two-phase timing device that aims to reduce water use from showerheads. The building owner sets the first phase of the shower to five, eight, or eleven minutes. When the time of the first phase ends, a beeper sounds and a minute later the water flow is reduced by two-thirds for five minutes, providing just enough water for the bather to rinse off. The Shower Manager takes a nine-volt battery.
Showers account for about 17% of all indoor residential water use, according to the EPA. Inefficient showerheads increase water and energy use, but some newer low-flow units have been faulted for delivering poor performance, leading people to spend more time in the shower, or remove the showerhead and replace it with an older, much higher-flow showerhead.
WaterSense has developed a specification that includes water efficiency, spray force, and spray coverage criteria. The first criterion is designed to reduce water use; the last two are aimed at maintaining a standard for superior shower performance, even as less water is being used. After doing field research in 2008, WaterSense developed tests that measure performance in spray force and spray coverage. Not directly included in the WaterSense criteria is “wetting performance” (though spray coverage could be a proxy for that) and “heat retention,” which is a function of droplet size. Showerheads that atomize water into very small droplets cool off very quickly, though atomizing showerheads may or may not satisfy the “spray force” requirement in WaterSense.
GreenSpec lists showerheads that use no more than 1.75 gallons per minute (gpm)—below WaterSense’s limit of 2 gpm—and are WaterSense labeled to address spray force and coverage
Shower satisfaction is a complex and highly variable user experience, much like thermal comfort. Including the spray force and coverage criteria is a good start, but look for additional or improved engineering and metrics as this field matures.
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