How to Size a Water Softener for Your Home
Now, let’s get personal: who lives in your house? Each person uses about 75–80 gallons of water per day (yes, including that epic pre-bedtime shower). Multiply that by the number of people in your home to get your daily water usage.
For example, a family of four uses roughly 300 gallons a day. Now multiply that number by your water’s hardness in grains per gallon—that’s the daily hardness load you need to remove.
So if your water is 10 gpg and you use 300 gallons, your daily load is 3,000 grains. That’s the number that matters.