DI Water System price Deionized Water Definition Deionized water means water that is partly or totally free from minerals, such as Na, Ca, Mg, Cl and SO4 etc., so it is also called demineralized water or DM water.聽 For many applications, water are used as a rinse or ingredient, so the ions are regarded http://www.rxdpurewatersystem.com/di-water-system/