Is descaling the same as demineralising?

There is a persistent misconception about softened water: that it is the same as demineralised water, resulting in a different acidity level that could damage your pipes. In this blog, you can read about the difference between water softening and demineralisation, and why a water softener does not cause damage to your pipes.

What is the difference between descaling and demineralising?

A water softener removes only the minerals calcium and magnesium from the water. Demineralised water, on the other hand, is stripped of all minerals and other solid particles, leaving simply H₂O: pure water without any other constituents. So, water softening affects only a very limited part of the water’s composition, whilst demineralisation strips the water completely bare.

Does water softening alter the acidity (pH) of your water?

No. During water softening, the Total Dissolved Solids (TDS) and carbonate hardness (KH) remain exactly the same as before the process. As these values do not change, the acidity (pH) of the water remains unchanged too. This is precisely where things go wrong with demineralisation: if you remove all the minerals from the water, the pH does change, and the water can become acidic and corrosive.

Is softened water bad for copper pipes?

No, on the contrary: limescale-free water is actually good for copper pipes. The coarse limescale in hard water actually causes pipes to wear out more quickly than softened water, which keeps pipes clean and smooth. This has been extensively researched by TNO on behalf of Aquacombi (TNO report 2012 R10424). You can read more about this topic on our pages about or soft water is corrosive and or Hard water corrodes copper pipes.

Where does the myth come from that water softening is the same as demineralisation?

This myth stems from a misunderstanding about naturally soft water. Soft water found in nature, such as rainwater, often has a high acidity level and does corrode copper pipes and other metals. Your tap water, however, is always pH-neutral, and a water softener does not change this. Softened water coming from your own water softener is therefore neither demineralised nor acidic, and does not corrode your pipes.