You can figure out the size of softener your family needs by multiplying the number of people in your household by 75, the average number of gallons used per person per day, and then multiplying this number by the number of grains per gallon of hardness minerals present.

So, for example, if you have a family of five and 10 GPG in your water, you have 3750 GPG requiring removal each day.

Compare this to the recharge cycle of the unit you're considering to see how frequently regeneration must occur. The idea is to get a unit that will go at least three days between recharges.

Ideally, it can also handle times when you have guests or larger-than-normal water needs.