Distilled Vs Deionised Water: What is the difference?


The terms “distilled water” and “deionised water” are often misunderstood.

Water Distillation

Water evaporation/condensation is one of the oldest methods of producing pure water and is also known as the “Thermal Method”.

The main drawback of this method is the very high cost of the electricity needed to convert the water into steam. In the process of steam formation along with water molecules, other solutes can enter the steam according to their volatility. Evaporation is then achieved in various ways such as vacuum above the water, heating, etc.

What’s happening in the process of distillation? It is really the separation between H²0 molecules and other impurities. The water molecules have the boiling point of 100°C while other substances have different boiling points. The substance that boils at a lower temperature evaporates first. As such, the boiling points of various impurities is higher, and theoretically, they will begin to evaporate. The water being of lower boiling point than other impurities will evaporate first leading to the separation of pure water (distilled water).


  • High Purity outcome


  • High power consumption
  • High waste water component (water condenser type)
  • Slow processing time

Water Deionisation

Water Deionisation filters (as known Ion Exchange, Strong Acid/Strong Base, and Nuclear Grade. These filters are fantastic for producing Ultra-Purified water for use with some of the most highly sensitive laboratory analytical instruments.

Deionisation is an on-demand process supplying purified water when needed. This is important because water at this extreme purity level degrades quickly. Deionisation alone does not remove all types of contaminants like dissolved organic chemicals. Deionisation filters are not physical filters with a pore size, hence they cannot remove bacteria or particulates.  

Deionisation is a popular choice for general laboratory applications due to the speed, simplicity, and efficiency of the methodology.


  • Low power consumption
  • Low waste
  • On demand process
  • Low setup cost

ISG developed a Deioniser that is commonly used in Australian laboratories and has proven to be very efficient and cost effective. See more online >>>



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