Definition - What does Distilled Water mean?
Distilled water is water produced by vaporization and condensation with high purity. In distilled water, many impurities have been removed through distillation, producing superior quality water.
Distilled water is safe to drink, but it is used more often for research purposes where water purity is essential or industrial uses where mineral deposits can cause corrosion and damage over time. It may also be used in steam irons to prevent calcium buildup or boiler scale.
Where exceptionally high purity water is required, double distilled water is used.
Corrosionpedia explains Distilled Water
Raw water usually contains a number of microscopic contaminants, along with dissolved minerals, such as calcium and iron. These elements can be removed from water through boiling until water changes to steam; this process known as distillation. When the steam is allowed to cool down and condense into liquid, the resulting purified water is called distilled water.
When water is heated in a distiller, any dissolved solids, such as salt, bacteria, calcium or iron, remain solid while the pure water converts to a much lighter steam and is drawn out for condensation. This water should ideally be nothing but hydrogen and oxygen molecules, with a pH level of 7 and no additional gases, minerals or contaminants.
Since the minerals and ions typically found in tap water can be corrosive to internal engine components, distilled water is preferable to tap water for use in automotive cooling systems. Similarly, it is also used in model steam engine boilers and model engines of other types to prevent scale buildup.
Despite its benefits, distilled water is particularly corrosive. With no minerals to give the water pH balance, distilled water acts like a magnet, absorbing chemicals (phthalates and bisphenols) from plastics, nickel from stainless steel, aluminum from aluminum containers, and carbon dioxide from the air.