The Difference Between Distilled and Demineralised Water

There is a common misconception that distilled and demineralised water are one and the same.  Seeing as both types refer to water in its purest form, it’s understandable that many people get confused.  Adding to this confusion, the uses for both types are very similar.  The biggest difference between these two forms of purified water is the process through which they’re obtained.

Water that has been stripped of all its mineral content and impurities has a wide range of uses.  Below are the main differences to help you distinguish between the two.

Distilled Water

The processes of distilling water involves boiling H20 at extremely high temperatures in a still until vapour forms.  The gas is then condensed in a separate container where it transforms into pure liquid a.k.a. distilled water.  This is a very expensive method of purification, as it requires a lot of electricity to convert water into steam.

The distillation process removes heavy metals and/or trace elements and salts. When the vapour rises, all these contaminants are left behind in the boiling pot.  For exceptionally high purity, water is double distilled or passed through an activated charcoal filter.

Distilled water can be used in automotive batteries, radiators, coolant systems, and for enamelling purposes.  Distilled water is typically favoured here as the presence of any impurities increases the risk of corrosion to equipment.

Demineralised Water

Deminarlised water undergoes a completely different purification process compared to distillation.  It also delivers a much purer result and is more cost-effective to produce.

As the title suggests, this water has all its minerals removed. It’s passed through ion exchange resins where hydrogen and hydroxide replaces the anions and cations.  Ions such as potassium, nitrate, sulphate, bicarbonate, chloride and calcium are typically removed from the water during this process.  However, organic chemicals remain in the water and are removed by passing the water through activated charcoal filters.

Demineralised water can be used in manufacturing instruments, pharmaceuticals, printed circuit boards and microelectronics.