Deionized water is water that is free from all charged atoms or molecules. It is water that has had all or almost all of its mineral ions removed, including sodium, calcium, copper, sulfate, iron and copper.
Deionization is a chemical process that utilizes specially manufactured ion-exchange resins that substitute hydrogen ion and hydroxide ion for dissolved minerals, which then come together forming water. There are three types of deionization: cocurrent, counter-current and mixed bed. Deionization is similar to distillation in that both processes produce purified water. However, the deionization does not completely remove uncharged organic molecules and other impurities such as viruses or bacteria. Distillation, on the other hand, produces pure water.