Shower or bath: Which uses more water?

"Take showers instead of baths to save energy," is an oft-repeated adage of water and energy conservation advocates. But the Department of Energy's water-heater-sizing pages now list the average shower as consuming 12 gallons and the average bath only 9 gallons of hot water. 

The DOE is also saying that homeowners are using from 15 to 30 percent of their total energy budget just to heat water—up from an earlier 14 to 25 percent estimate. So is soaking instead of scrubbing the way to go?

A spokeswoman for the EPA (which provided the figures to the DOE) says the new figures were based on a study it commissioned in 2000 by independent water-engineering-and-management firm Aquacraft. Ten homes in Seattle were fitted with data loggers on the main water meters a separate meter was placed on the feed line to the water heater and the results measured over two separate two-week periods.

"The nine gallons was actually the actual average draw of water into a bathtub, but you're talking about an event that can involve more than one draw of hot water," says Aquacraft President Bill DeOreo. "So that's not an accurate measure of total average use."

Consumer Reports' own experts believe the previous 20 gallons of hot water per bath that the EPA was using (which was in turn based on a studies done by the Gas Appliance Manufacturers Association) to be still a better benchmark.

They also stress that the best way to save hot water is to take showers rather than baths, limit the time of showers, use a low-flow showerhead, and turn off any supplemental showerheads in each shower stall.

Many utilities and municipalities are following this advice. The Portland, Oregon Water Bureau has given away over 4,500 1.5- gallon-per-minute showerheads and 4,000 five-minute "Shower Timer" hourglasses to its customers.

"The hourglasses aren't as functional as the low-flow showerheads and aerators we give away; they're more of a behavioral tool," says Sarah Statner of the Portland Water Bureau. "But we get a lot of positive feedback and hear they inspire more conversations about conservation than any showerhead every will."

Also backing the move for water economy is the popular eco-blogger Crunchy Domestic Goddess, who has issued her own Five-Minute Shower Challenge that's drawn numerous responses.—Gian Trotta

Essential information: Find out about the wide variety of high- and low-flow spraying options available Showerheads special. Our GreenerChoices.org Web site offers "50 Ways to Save Water." And see our October issue for a special comparing the performance of tankless, or on-demand, and conventional storage-tank heaters.