Water softeners, by certification and five-year cost.

The salt setting. A softener can be set to use more or less salt each time it regenerates. Less salt gets more hardness out of each pound but regenerates more often. Each softener here is worked out at the setting its efficiency rating is stated at or, where no listing shows a rating, the maker’s default. Never at a setting picked because it is cheapest. NSF/ANSI 44 requires every capacity a maker publishes to name its salt setting, and each softener’s page lists all of them, with the manual they come from.

The arithmetic. Your water brings in its hardness, in grains per gallon, times the gallons you use. Each regeneration restores the grains the setting is rated for, using that setting’s salt. No reserve is counted: a softener that regenerates before its resin is spent, as many do so you never run out, uses more salt than shown. Where a softener would have to regenerate more than once a day at its setting, it would need a higher one, which uses more salt for each grain. A softener rated for less hardness than your water drops down the list.

Salt. $9.88 for a 40-lb bag of Morton Clean and Protect water softener pellets, The Home Depot’s single-bag price on Oct. 13, 2026; change it to what you pay. Potassium chloride, which adds no sodium, costs 3 to 5 times as much and is 15 to 30 percent less efficient, the University of Minnesota says.

Water. Regeneration water is given in gallons, not priced, because water and sewer rates differ too much from town to town.

Sodium. Softening adds about 8 mg/L of sodium for each grain per gallon it removes, Nebraska Extension and NDSU Extension say. Nebraska suggests leaving one cold tap unsoftened for drinking and cooking.

Prices. Each system is priced at its maker’s list price or, where the maker publishes none, the regular price at the store the maker sends buyers to, on the date shown on its page. Never an Amazon price.

On NSF’s listings, an efficiency-rated softener removes at least 3,350 grains of hardness for each pound of salt and uses 5 gallons of water or less for every 1,000 grains it removes. Only softeners that regenerate on demand, when a meter or sensor says the resin is spent, may claim it, NSF’s Rick Andrew has written. NSF/ANSI 44 doesn’t require it, so a certified softener can lack it.

California goes further. A softener installed since 2002 that drains to a community sewer must regenerate on demand and be certified at 4,000 grains per pound or better, under Health and Safety Code section 116785.