Your own per capita use: 0 gallons per day
Does 0 gallons sound about right for the day's indoor-water activities? You probably realize that the number is only an estimate, and, we're using the higher (not energy efficient) values here. First, we're not taking into account everything you use water for, such as cooking and dog washing. And, water use for all activites vary by individual. You might use five gallons to wash dishes by hand, but your sister might use ten. You might leave the water running when you brush your teeth, but your brother might not. If you live in a newer house, your toilet probably uses less water per flush than the toilet in a very old house. Newer houses also have shower and faucet heads that use less water than before (look at the end piece on your sink faucet -- it should have the number of gallons per minute that it will allow stamped in it).
Here are the numbers we used in our calculations:
Bath: 36 gallons is a reasonable average
Shower: 2.5 gallons per minute
Old showerheads may use 4 gal/min whereas newer low-flow showerheads use about 2.
Teeth brushing: 1 gallon
Depends on if you let the water run while brushing
Hands/face washing: 1 gallon
Face/leg shaving: 1 gallon
Depends on if you let the water run while shaving.
Dishwasher: 20 gallons/load
New energy-efficient models may only use 4 gallons.
Dishwashing by hand: 4 gallons/minute
With a low-flow faucet head, might be 2 gallon.
Clothes washing (machine): : 40 gallons/load (top loading)
Front-loaders may use about 20 gallons/load. New models use less water than old models.
Toilet flush: 3 gallons
for an older model. New energy-efficient toilets might only use 1-1.6 gallon/flush.
Glasses of water drunk: 8 oz. per glass (1/16th of a gallon)