all you need is a calculator or some paper!
as much as Americans do... there´s no difference.
An average person uses 123 gallons of water a day. Most families would consist of 4 people, so about 492 gallons a day. But remember that you can't have a precise answer. It's only an estimate.
8 glasses a day
Twenty cups is average, but it is healthy to drink fifteen cups of water a day.
150 gallons
Seven to ten cups per day is a good average.
500 galons
about 300L/perday
about 64oz a day
293 gal.
1,5 Litres a day!
About 80-100 gallons each day!