Water softeners use an ion exchange process to remove both calcium and magnesium from the water. Softeners utilize a plastic polymer with a positive ionic charge that holds on to negatively charged calcium and magnesium ions in the water.
Several popular water filtration companies make salt-free water softeners. The idea of a salt-free way to soften water is appealing from a maintenance standpoint, but unfortunately, these systems do not work.
Salt-free water softeners do not soften water - they condition it. Saltless systems chemically transform the magnesium and calcium so they do not adhere to surfaces.
Because salt-free systems do not "capture" calcium and magnesium, there is no need for a regeneration cycle to clean the resin bed and flush the minerals.
Disadvantages Salt-Free Water "Softeners"
Because the hard water minerals are not actually captured by salt-free water softener systems, there is no need for salt or a regeneration cycle to purge the minerals down the drain. Since the very definition of water softening requires that hard water minerals be REMOVED, and the salt-free process only CHANGES the minerals, allowing them to remain in the water, salt-free water softeners don't actually soften water – rather, they are for "water conditioning".
Penn State University laboratory tests found "no discernible change in water hardness" in salt-free softeners.
With a salt-free water softener, you'll still have hard water and the following problems:
Hard water spots on your glasses and dishes
Soap-scum buildup up on shower doors
Scale buildup on fixtures and water-using appliances
75% more soap, detergent and shampoo useage
Water heating expenses 30% above the cost of heating soft water
The only way to truly soften water is with an < a href = "https://www.waterbionics.com/whole-house-water-filtration/#section_9ufgT">ion-exchange process utilizing sodium chloride (or potassium chloride).