Water softening involves the removal of cations, namely calcium, manganese, and iron, in hard water. This is often achieved using various resins in order to decrease lime build up, iron staining, soap scum, dry skin, and can extend the life of various plumbing equipment and laundry fabric. The water softener replaces the incoming magnesium and calcium ions with sodium ions or potassium ions, depending on the type of regenerant used, salt (NaCl) or potassium Chloride (KCl).