How Much Salt Should Be in a Water Softener?

The rule of thumb

• Refill at about half full. Never below a quarter; Whirlpool's manual says to always add salt when the tank is less than 1/4 full.
• Fill to about three-quarters full. Leave a few inches of space at the top.
• Keep the salt above the water. Hellenbrand's troubleshooting table tells owners to keep the salt level above the water level.
• Check it once a month, or every two or three weeks until you know your usage, as Whirlpool suggests.

Morton says 2 to 5 inches of water at the bottom of the salt tank is typical. So in a normal tank you're looking down at dry salt, with the brine hidden underneath.

Why not fill it to the top?

A tank packed to the lid isn't better. Diamond Crystal advises against overfilling. Salt pressed down under its own weight, especially in a humid basement, is how a salt bridge forms: a hard crust that hangs above the water while the salt below dissolves away. The tank looks full and the water turns hard.

So add a bag or two at a time rather than topping off with five. If the salt hasn't gone down in a month or more, push a broom handle straight down. Hitting something solid partway down usually means a bridge. Our salt bridge page explains how to break it safely.

How much salt does a softener use?

It varies with hardness, household size and how efficiently the softener is set up. Some published averages:

Per regeneration, the amount is set by the softener. Hellenbrand's H100 manual lists 4.5 pounds of salt per regeneration for its smallest model and 36 pounds for its largest at the high-efficiency setting. A bigger softener uses more salt per cycle but regenerates less often.

If you're using a lot more than these averages, look at the hardness setting first. Minnesota's health department says a hardness setting that's too high makes the softener cost more to run and wastes water. See water softener hardness setting.

When to add salt

Pick a routine and tie it to something you already do. Morton suggests a calendar date, every air filter change, or every oil change, adding at least two bags each time. Morton's iron-fighting pellets carry the same instruction: two bags every two months, keeping the tank at least half full.

What matters more than the schedule is not running out. With no salt, the resin can't recharge, and hard water reaches the house within a few days. Hellenbrand says that after refilling an empty tank you should wait at least two hours before starting a regeneration, so the water has time to turn to brine.

Potassium chloride is different

If you use potassium chloride instead of salt, check your manual for fill limits. The Whirlpool WHES48 says not to fill above level 4 on its brinewell scale with potassium chloride and to keep no more than 60 pounds in the tank at a time. Morton's potassium pellets are labeled for one bag a month with the tank at least half full.

What if there's a lot of water and little salt?

A tank that's mostly water is a different problem. Normal is a few inches. A plugged injector, a plugged or kinked drain line or a defective brine line flow control can leave the tank half full of water; Hellenbrand lists all three among the causes of excess water in the brine tank. See brine tank full of water.