The average shower uses about 5 gallons of water per minute. The average shower time for a person is around ten minutes. If a person were to shower once a day they would use 350 gallons of water per week showering. This comes out to 18,250 gallons a year.
To help cut back on the amount of water used my idea is a small water proof timer that a person could take with them in the shower. To make it more convenient the timer would have a elastic strap that would allow it to be put around a shampoo or body wash container. This timer would allow the user to time there average shower, then after finding out what their average shower time is the user could then set the timer for a couple minutes less than their average time helping the person adjust to a shorter shower time. If a person could cut off 2 minutes a day to their average shower time it would save 70 gallons of water a week and 3,650 gallons of water a year.