So, the tub is rarely filled to capacity before taking a bath. A low-flow showerhead uses about two gallons a minute, or 20 gallons for a 10-minute shower. A standard showerhead uses 2.5 gallons a minute, or 25 gallons for 10 minutes. Either way, the shower saves water – as long as you don't go past 10 minutes.

So, the tub is rarely filled to capacity before taking a bath. A low-flow showerheaduses about two gallons a minute, or 20 gallons for a 10-minute shower. A standard showerhead uses 2.5 gallons a minute, or 25 gallons for 10 minutes. Either way, theshower saves water – as long as you don't go past 10 minutes.