Softening Systems:

When water contains a significant amount of calcium and
magnesium, it is called hard water. Hard water is known to clog
pipes and to complicate soap and detergent dissolving in water.
Water softeners are specific ion exchangers that are designed to
remove ions, which are positively charged. Softeners mainly
remove calcium (Ca2+) and magnesium (Mg2+) ions. Calcium
and magnesium are often referred to as hardness minerals'.
Softeners are sometimes even applied to remove iron. The
softening devices are able to remove up to five milligrams per
liter (5 mg/L) of dissolved iron.