For Hardness Reduction, Softening your water by releasing Hydrogen (H+) ions or other positively charged ions in exchange for impurity cations present in the water. The process involves passing water containing hardness ions, namely calcium (Ca2+) and magnesium (Mg2+) through a column containing a strongly acidic cation exchange resin in the sodium (Na+) form (i.e. the exchangeable cations are sodium). The calcium and magnesium ions are exchanged for an equivalent number of sodium ions. The resin, once exhausted, (i.e. all the available sodium ions have been exchanged) must be re-charged. This entails passing a solution containing a high concentration of sodium salts such as brine (sodium chloride) through the ion exchange resin - a process known as regeneration.