Natural occurring water contains many dissolved solids in dilute forms which are usually various types of salts. These solids are known as total dissolved solids (TDS). Demineralization is the process of removing nearly all dissolved solids and mineral ions from water.
In industrial water treatment, demineralization refers to the removal of dissolved solids from feed water and process streams. By definition, demineralization is the near-total removal of inorganic salts from water. In most industrial process water treatment applications, this is accomplished through ion exchange.