Salt Based vs Salt Free Water Softener: What Each One Actually Does

A salt based softener takes calcium and magnesium out of your water and puts sodium in their place. A salt free water softener does not take them out. It leaves the minerals in the water and tries to keep them from sticking as scale. So the real question is whether you need them gone, or only need less buildup.

Penn State Extension calls it ion exchange. Water runs through a bed of resin beads that are coated in sodium. The beads grab the calcium and magnesium and let the sodium go. The water leaving the tank is soft.

The beads fill up. When they do, the unit rinses itself with salty water and sends the hardness down the drain. Penn State says that rinse uses about 50 gallons of water each time.

Nebraska Extension says the process removes nearly all of the calcium and magnesium. It is also the most common way homes deal with hard water.

You get soft water. You also get three things you should know about first.

The first is sodium. Nebraska Extension puts the trade at about 8 milligrams per liter of sodium for each grain per gallon of hardness. Water that started at 10 grains per gallon ends up with about 80 milligrams of sodium per liter. If anyone in the house is on a low sodium diet, that is a doctor's question.

The second is salt in the ground. The Minnesota Department of Health warns that one teaspoon of salt is enough to pollute five gallons of water for good.

The third is upkeep. There is a tank you fill and a drain line to run.

The Minnesota Department of Health has a fix for the first one. Keep one cold tap for drinking and cooking that skips the softener. Toilets and hose taps do not need soft water either.

People call it a salt free water softener, but it does not soften the water. It is a different machine with a different goal. It leaves the calcium and magnesium in your water. It changes their form so they are less likely to stick to pipes and heating parts. There is no salt to buy and no drain line to run.

Here is the tell. One maker of a salt free unit publishes no grain rating for it at all, because it is not an ion exchange softener. The page lists a top hardness it can handle, 81 grains per gallon, and no capacity number.

That is not a trick. It is the honest result of a machine that does not remove anything. There is nothing to count.

Fixr lists a few types of salt free gear. Magnetic units run $200 to $400 for the unit. Electronic units run $200 to $600. Descalers as a group run $200 to $2,000. Ion exchange softeners run $500 to $2,000.

Read Fixr's own notes on those cheaper types before you buy one. It says electronic units do not remove minerals. It says magnetic units can still leave a stain once the water has been away from the magnets. It says neither type is usually recommended for very hard water.

Pick a salt based water softener if the minerals need to go. That means hard water, scale in the kettle and the heater, spots on the glasses, and soap that will not lather. This is also the only type with a grain rating, so it is the only type you can size to your own water.

Pick salt free if you cannot run a drain line, or if you have to keep salt out of the water for health or septic reasons. Go in knowing your water stays hard. You are buying less scale, not soft water.

One more thing worth knowing. Nebraska Extension says no federal, state or local law covers home softening systems. The industry checks its own work. NSF and the Water Quality Association test and certify units. A certification mark is worth more than a claim on a box.

Every softener in our table is a salt based unit. We do not rank a salt free system, because a system with no published grain rating cannot be sized or scored the way we score the rest.

Start with your hardness number, because it decides the rest. City water reports list it. On a well, a lab test gives it to you.

Then answer one question honestly. Do you need the minerals gone, or do you need less buildup? Scale in the heater, spots on the glasses and soap that will not lather are hardness problems, and only the salt based type removes hardness.

If you go salt based, check two things in the house before you buy. There has to be a drain the unit can rinse into, and floor space for a salt tank you can reach to fill.

If you go salt free, check the maker's page for a grain rating. If there is not one, there is no way to size the unit to your water, and you should treat any softening claim on the box as a claim rather than a number.

Either way, look for an NSF or Water Quality Association mark. Nebraska Extension says nothing in the law regulates these systems, so a certification mark is the only outside check you get.