Deionisers are designed to produce high purity treated water required by pharmaceutical and electronic industries. A demineralizer removes total dissolved salts from the raw water by an ion exchange process in this process the cations are exchange for hydrogen and anions for hydroxyl ions to give chemically pure water. Two bed deionisers give water conductivity less than 30 micro- siemens and PH will be in the range of 7.5-9.5.and TDS less than 10PPM.