Most municipal water systems in the
United States have hard water. Hard water is water that contains mineral
salts of calcium and magnesium principally as bicarbonates,
chlorides, sulfates, and sometimes iron.
There are many problems
associated with hard waters. For example hard water causes lime scale
deposits in pipes and radiators. Soap does not dissolve in hard
water and finally hard water is not good for drinking. Ion
Exchangers are used to remove calcium and magnesium ions from
water and substitute them with sodium ions or hydrogen ions.