An important step in developing a sustainable water supply is figuring out how much water is needed to supply the predicted demand. In many situations it does not make economic sense to go to the expense of developing a water supply with a capacity far exceeding what is forecast to be needed.
Here are some “ballpark” figures (gallons per day, or GPD) for water usage in the United States from federal government sources:
daily human consumption per capita: (modern household, conservation minded) 50 GPD; (modern household, not conservation-minded) 100 GPD
daily water consumption per horse (winter) 10 GPD; (summer) 20 GPD; (nursing mare) 20 – 25 GPD
daily water consumption per cow (winter) 6 GPD; (summer) 15 GPD; (lactating cow) 11 – 18 GPD; (bull) 7 – 19 GPD
Useful information: 1 gallon per minute of sustainable well capacity = 1440 GPD