How Is Demineralised Water Made?

by Jessica Clifton

Demineralised water is a common form of high grade purified water, and it can be made in several ways. It’s also known as demi or demin water and is simply water which has had its minerals removed.

How Is Demineralised Water Made?

There are various ways of producing demineralised water, and we’ll look at a few of them in a little more detail.

How Is Demineralised Water Made?

Making Demineralised Water Through Deionisation

People often think that demineralised water is the same as deionised water, even though they are two different (although similar) products. They can both be produced by deionisation, but the difference is that demineralised water contains no minerals and deionised water contains no ions.

While deionised water is always made through the deionisation process, it is just one of the ways demineralised water is made. Deionisation uses specially-manufactured ion exchange resins. There are positively and negatively charged resin beds which remove dissolved solids from the water flowing through them.

Making Demineralised Water Through Membrane Filtration

In the membrane filtration process, a semi-permeable membrane captures and removes dissolved solids, including molecules and ions, viruses and bacteria from water. The membrane has pores that allow certain micro-particles to pass through while preventing other micro-particles from passing through.

Droplet and a ripple of water

Two types of membrane filtrations are used in the demineralisation process to remove these extremely small impurities.


Nanofiltration removes approximately 80-85% of minerals and salts as well as 99% of all bacteria from water. Nanofiltration membranes are porous, but more so than reverse osmosis membranes so the demineralised water produced, while extremely high quality, isn’t quite as pure.

Hyperfiltration (reverse osmosis)

Reverse osmosis removes approximately 90-95% of minerals and salts as well as 99% of all bacteria from water. An advantage of reverse osmosis is that you can select which molecules and ions are taken out of the water, and which ones remain. This means the end product is exactly as you want it as you have a lot of control over the process.

How Demineralised Water Is Made Through Electrodialysis

Electrodialysis is another a membrane filtration process, this time also using an electric field.

By combining electrodialysis with ion exchange resins, demineralised (and deionised) water is produced without the need to regenerate the ion exchange resins chemically, which is the case in the deionisation process.

Can You Drink Demineralised Water?

At ReAgent, we don’t recommend that you drink demineralised water, especially when it is industrially produced and extremely pure. Demineralised water can have negative health effects, it is an ‘aggressive’ water (it leaches metal, for example), it doesn’t taste nice and it doesn’t quench thirst.

At ReAgent, we sell demineralised water in sizes ranging from ampoules to 25,000L. If you’d like to find out more or to discuss your demineralised water requirements, contact our team today.


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