Is Demineralised Water the Same as Deionised Water?

by ReAgent Chemicals

There are many forms of purified, high-grade water, and it can get confusing. We’ll take two common types of purified water, demineralised and deionised, and look at their similarities and differences. We’ll find out whether demineralised water is the same as deionised water shortly. But first, a little more about each type of water…

What Is Demineralised Water?

Is Demineralised Water the same as Deionised Water?

Demineralised water is purified water which has had all of its naturally-occurring minerals removed via ion exchange. These minerals include magnesium, calcium and sodium. This makes the water ‘soft’ rather than ‘hard’.

Potential spoiler alert! Removing minerals from water using an ion exchange is the same method of purification used for deionising water. However, demineralised water can also be produced through electro-dialysis and membrane filtration amongst other methods.

What Is Demineralised Water Used For?

The demineralisation process produces high-quality water – without removing the minerals, the water could interfere with and contaminate the various industrial processes that demineralised water is used for, including:

  • Laboratory testing
  • Analytical chemistry
  • Cleaning lab equipment
  • Coolant systems

What Is Deionised Water?

Is Demineralised Water the same as Deionised Water?

Deionisation removes the impurities found in water on an ion level. Deionised water has a very consistent chemical composition, and is therefore useful in manufacturing processes which require stable and reliable components.

Deionised water does not contain any metallic or mineral impurities, but unless a strong resin bed is used in the ion exchange process it will normally contain viruses and bacteria. In fact, different qualities of deionised water can be produced, and that makes it suitable for a range of industrial and scientific applications – ones which are very similar to (or the same as) demineralised water.

What Is the Difference Between Demineralisation and Deionisation?

As you’ve probably guessed by now, demineralised and deionised water are almost identical and they are often talked about interchangeably. But even though these two types of water are generally produced using the same method of ion exchange, there are differences in the resulting product which you should be aware of if you are looking for purified water for certain scientific and industrial processes.

Essentially, it is as their names suggest; demineralised water is free of minerals, and deionised water is free of ions. While the ion exchange process results in high-quality, mineral-free water, there are other forms of water such as distilled water which is even purer.

It should be said that neither demineralised water nor deionised water is generally safe for human consumption especially when they are very high purity, as all the minerals which are good for us have been removed.

At ReAgent, we sell demineralised and deionised water in sizes ranging from ampoules to 25,000L tankers. And we don’t get them confused – but if you’re not sure which is most suitable for your needs, contact our team today.


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