The removal of calcium and magnesium, the ions which are the principle cause of hardness, from water.
Compare with water softener and water hardness. Removal of Ca2+ and Mg2+ from water to prevent undesirable precipitation reactions from occurring in plumbing, pools, washwater, and boilers.
To soften water fully, the minerals (calcium and magnesium) that cause hardness must be removed. These minerals are removed by ion-exchange.
The substitution of sodium ions for ions of dissolved minerals (hardness) found in water.
To exchange sodium for the hardness in water by ion exchange.
The reduction/removal of calcium and magnesium ions, which are the principal cause of hardness in water. The cation exchange resin method is most commonly used for residential and commercial water treatment.
A water softener reduces the calcium or magnesium ion concentration in hard water. These "hardness ions" cause two major kinds of problems. The metal ions react with soaps and calcium sensitive detergents, hindering their ability to lather properly and forming an unsightly precipitate— the familiar scum or "bathtub ring".