Deionized (DI) water is water that has been treated to remove all ions – typically, that means all of the dissolved mineral salts. Distilled water has been boiled so that it evaporates and then re-condensed, leaving most impurities behind. ... The resulting water is, therefore, very pure.

Should you drink deionized water?

While it's okay to drink distilled water, you should not drink deionized water. In addition to not supplying minerals, deionized water is corrosive and can cause damage to tooth enamel and soft tissues. Also, deionization does not remove pathogens, so DI water may not protect against infectious diseases.

Can you use deionized water for cooking?

Distilled water is very “soft” because of the absence of minerals. Because it's mineral free, it very readily and aggressively absorbs other minerals that it comes into contact with. For this reason, cooking vegetables in distilled water is not recommended, because the water leaches the minerals out of them.