Industrial Demineralisers are made up of two rubber-lined mild steel or frp pressure vessels containing ion exchangers, connected in series. The first column contains the cation exchanger and the second column contains the anion exchanger. The cation exchanger converts all ionized solids in the raw water to their equivalent acids. The anion exchanger absorbs the acids when the acid water flows through it and produces demineralised water with minute traces of dissolved solids. When the capacities of these ion exchangers are exhausted, they are regenerated. The cation exchanger is regenerated with a dilute solution of hydrochloric acid and the ion exchanger is regenerated with a dilute solution of caustic soda.