Can mineral water be filtered? — Explainer video

Transcript

Can mineral water be filtered? What is permitted, and what is not.

Tap water may be treated so that it is impeccable when it comes out of the tap. For natural mineral water, the opposite applies: it must already be so pure underground that it needs nothing to make it drinkable. The law calls this original purity.

Only a few, narrowly defined processes are permitted: decanting and filtering, for example to separate iron or manganese compounds, removing or adding carbon dioxide, reducing fluoride. Any form of disinfection is prohibited. Tap water, by contrast, may also be treated with activated carbon, UV light or chlorine.

There are limits on fine filters too. For natural mineral water, microfilters may only remove particles such as rock fragments. Pore sizes below 0.8 micrometres alter the microbial content and are not permitted. The Federal Food Safety and Veterinary Office clarified this in 2025.

Activated carbon binds dissolved substances, among them residues of plant protection products. This is a proven process in drinking water treatment. For natural mineral water, it is not permitted: pesticides and their breakdown products must not occur in it at all, and there is no provision for removing them, the federal office notes. Water filtered through activated carbon may be sold, just not as natural mineral water.

The same logic applies in the EU: there too, any form of disinfection is prohibited. Original purity cannot be manufactured. It has to be there from the start.

The same applies to Piz Sardona: what is in the bottle must already be that way at the spring. The still variety goes into the bottle without added carbon dioxide. Carbon dioxide is added to the sparkling varieties, one of the few permitted processes.

That makes origin all the more important. The water seeps into the ground at more than 2,000 metres above sea level, in an area without arable fields, vegetable or fruit crops and without vineyards. It then travels through the rock for around twelve years. According to Mineralquellen Mels AG, no pesticides are detectable in it, as original purity requires of every natural mineral water.

More on this in the Piz Sardona Academy.