Taking a bath generally uses a more water than taking a shower. The average shower uses 2.5 gallons of water per minute, so an eight minute shower will use 20 gallons of water. The average bather will use 35 gallons of water. A short shower is the way to go if you're conserving water. Love your bath? There are ways to save in the tub! When running a bath, plug the drain before you turn the water on and adjust the temperature as the tub fills. Fill the tub less than half way for an adult, a quarter or less for children. And if you have more than one small child, consider bathing them together to save time and water.