A water softener uses a medium that serves to exchange "ions" of calcium and magnesium with sodium and potassium. Traditional water softeners use salt as the medium, and salt-free water softeners from Magna-Tek do not.
This occurs in four steps:
During the softening process sodium is released from the exchange media into the output water. For every grain of hardness removed from water, 8 mg/1 (ppm) of sodium is added. People on restricted sodium intake diets should account for increased levels of sodium in softened water. Salt-free water softeners don’t have any of these risks or disadvantages.
Salt Water Softener