Water Softener
Sizing Calculator

Find the Clean Water Store softener that fits your hardness, household water use and peak flow, and how much salt it will use each month.

1
Water Hardness
GPG
If your test is in ppm or mg/L, divide by 17.1 to get GPG.
ppm
Each 1 ppm of iron adds ~4 GPG of effective hardness. Softeners handle up to ~3 ppm dissolved iron.
2
Household Size
gal/day
Leave blank to use 75 gallons per person. From a water bill: gallons per month ÷ 30. Count only the water that goes through the softener.
GPM
Don't know it? Measure your pump flow rate.
Recommended Softener Size
Required Capacity
—
grains between regenerations
Compensated Hardness
—
GPG (hardness + iron)
Daily Use
—
gallons/day

How We Calculate

Capacity needed = Compensated Hardness (GPG) × Daily Water Use (gallons) × Days Between Regeneration
Compensated Hardness = Water Hardness + (Iron ppm × 4 GPG)
Softener resin provides ~30,000 grains per cubic foot at the standard salt setting (15 lbs/cu ft), ~20,000 at the efficient setting (6 lbs/cu ft)
Flow: the softener's Service flow rating (Clean Water Store Spec Master) must cover your peak flow. Its Maximum rating is the top it handles (about a 15 psi pressure drop there).
Salt efficiency tip: A softener achieves best salt efficiency when you use about 6 lbs of salt per cubic foot of resin (~20,000 grains/cu ft). Using 15 lbs/cu ft gets ~30,000 grains. Oversizing slightly and regenerating more often with less salt saves salt and money in the long run.
Need help sizing your system? Call us at 888-600-5426
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