A process used to purify water by the removal of mineral ions such as the cations calcium, copper, iron, and sodium, and chloride and sulphate anions. The process uses ion exchange resins that exchange the hydrogen and hydroxide ion for dissolved minerals and then form water. Deionized water is used for many purposes such as the cooling water in nuclear reactors. It is also used as an alternative to distilled water in the laboratory. With the absence of ions, deionized water does not conduct electricity.