GPG
(Grains per Gallon) hardness or PPM (parts per million) hardness
Iron
level in GPG
Gallon usage per day
Average water usage per day is 100 GPD/pp (gallons per day per person)
Calculations
Determine the hardness of the
water. This can be obtained from the Water Department or by yourself with test
strips. The hardness of water is measured in GPG which stands for grains per
gallon.
Add that number to the iron
level. This number is the total hardness GPG that needs to be
removed.
You then multiply (GPG
hardness + GPG iron) X 100 GPD X the number of people in the household X 7 (days of the
week)
Example: If you have a 4 person household, with a 10 GPG hardness + 2 PPM iron with an average usage of 100 gallons a day per person. Your formula will be as follows: 4 x (10 + 2) x 100 x 7 = 33,600
The calculated number should be the size of the water softener.
