Definition - What does Demineralization mean?
Demineralization is a process in which any salts (e.g., potassium, chlorine, magnesium) and ions (cations and anions) are removed from water to make it suitable for home or industrial purposes. Demineralized water reduces the corrosion rate.
Demineralized water is also known as demi water.
Corrosionpedia explains Demineralization
Demineralized water is preferable for industrial purposes because it has a lower salt content, which will reduce the conductivity of the water and decrease the corrosion rate.
Another effect of a low salt content is that the water is less protective and will not form a layer of calcium carbonate (CaCO3) or other salt, thus protecting steel from corrosion. The corrosion rate of the demineralized water also depends on the oxygen and carbon dioxide content; water that is stored in an airtight container and not in contact with the atmosphere will have a lower corrosion rate.