Demineralization is often a term used interchangeably with deionization. Demineralization is essentially removing all the minerals that can be found in natural water. This process is usually done when the water will be used for chemical processes and the minerals present may interfere with the other chemicals. All chemistic and beauty products have to be made with demineralized water for this reason.[4] With the demineralization process, the water is "softened", replacing the undesired minerals with different salts. Demineralized water has a higher conductivity than deionized water.

DM Plant is also known as Demineralization plant. It works on the operating principles of ion-exchange to remove the dissolved mineral ions like sodium, magnesium, calcium etc from the water. DM water plant has 3 vessels namely cation exchanger, anion exchanger & Mix-Bed ( Super charge ) vessel.

When the water gets passed from these three vessels it becomes ion free. As the cations get exchanged with hydrogen ions in first bed, the anions are exchanged with hydroxyl ions, in the second one. The resultant water is chloride free having zero TDS & Zero conductivity. This water is called Demineralised water or Deionized water.