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). Regeneration is normally achieved with an automatic control head. The common steps are backwash, brine draw, slow rinse, refill brine tank and fast rinse and return to service. The method of initiating a resin bed regeneration and clean up can be based on a time estimate, gallons usage of water or hardness sensors.
The hardware comes in various sizes depending on daily usage, peak gallon per minute, incoming hardness load and the desired water hardness out of the system. The number of tanks can be one, two, three, four or more. The method of initiating regeneration can be based on time, volume of water previously passed through the system, or the measured water hardness coming out of the system.