Hardness
Spots on the glass, scale in the kettle, stiff laundry
Hardness is calcium and magnesium. The lab reports it in milligrams per liter; the softener world counts in grains per gallon.
One grain per gallon is 17.1 mg/L. A report that says 171 mg/L is 10 grains, which is hard on the common scale.
A softener is sized to the grains your household uses in a day, not to the size of the house.
The common scale
Where your number falls
Soft
Under 1 grain per gallon (17 mg/L).
Slightly hard
1 to 3.5 grains per gallon.
Moderately hard
3.5 to 7 grains per gallon.
Hard
7 to 10.5 grains per gallon.
Very hard
Over 10.5 grains per gallon, past 180 mg/L.
Sizing, in numbers
Grains in, days between regenerations
An example, not your house. Four people using about 300 gallons a day, on water at 10 grains, use about 3,000 grains a day. A softener rated for 32,000 grains then regenerates about every ten days.
A softener too small for the house regenerates too often and wastes salt. One too large sits on stale resin. The proposal shows your numbers worked this way.
Your hardness, from the lab sheet
Your household's daily water use, which we ask about
Salt use per regeneration, in the proposal
Softener questions
Does a softener add sodium to the water?
It swaps hardness minerals for sodium or potassium, and the amount depends on how hard the water is. If you are on a sodium-restricted diet, ask your doctor. We can leave one tap unsoftened.
Should the outdoor spigots be softened?
Usually not. We can plumb the softener to leave the hose bibs and the irrigation on hard water.
Can hard water hurt the water heater?
Scale builds on the heating element and the tank over time. A softener slows it down; it does not undo scale already there.
What if my water is hard and has iron?
Iron in the water can foul softener resin. We usually treat the iron first, then soften. The proposal says the order.
Do I have to use salt?
Salt-based softeners use salt. Other approaches exist and do not do the same job; we explain the difference before you choose.
Know your grains first
Send the report, or ask for sample bottles.