Bath vs. Shower Water Footprint Calculator

A standard bathtub holds 35-50 gallons when full. A typical 8-minute shower at 2.5 gpm uses 20 gallons. So an average shower uses significantly less water than a full bath. However, a long shower (15+ minutes) in a standard showerhead uses more water than a half-full bath. The tipping point is roughly 14 minutes at 2.5 gpm.

Water heating energy depends primarily on the volume of hot water used. Since baths typically use more water than showers, baths generally cost more to heat. The type of water heater matters too: heat pump water heaters use about 3x less electricity to heat the same water as standard electric resistance heaters.

A WaterSense-certified low-flow showerhead uses 1.5-2.0 gpm vs. 2.5 gpm for a standard head, saving 0.5-1.0 gallon per minute. At 8 minutes per shower and once per day, that's 1,460-2,920 fewer gallons per year per person. Combined water and water heating savings typically run $50-150 per person per year.