Our demineralised water plants in Melbourne work by removing mineral salts from water using the ion exchange process. The system removes ionic mineral pollutants almost completely. Demineralised water is also called deionised water since it has had its mineral ions removed. Mineral ions like sodium, calcium, iron, and copper are common ions present in water. A demineralised water plant uses specially manufactured ion exchange resins to provide ion exchange for the replacement of mineral salts.