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Sparkling water

EU law recognises four different sparkling waters, and the difference is where the gas came from. This page sets out the four legal descriptions, what carbonation does to teeth and bones according to the evidence, and which waters here belong to which category.

The four descriptions

Directive 2009/54/EC does not let a producer decide what to call the bubbles. The description follows the origin of the gas and how much of it there is relative to the source:

The distinction is a provenance statement rather than a quality ranking. A naturally carbonated water usually has a finer, softer bubble, and it tends to be more heavily mineralised for a good geological reason: carbon dioxide under pressure in an aquifer is an efficient solvent, so the same gas that makes the water fizzy also dissolves the rock that makes it mineral-rich.

Which is which here

Teeth

Dissolving carbon dioxide in water produces carbonic acid, and carbonic acid does lower the pH — plain sparkling water typically sits somewhere around pH 5 to 6 rather than the 7 of still water. That is the whole basis of the "sparkling water ruins your enamel" claim, and it overstates the case considerably.

Carbonic acid is weak and unstable: it breaks straight back down into water and carbon dioxide, which is why the fizz escapes. It has no chelating action on calcium the way citric acid does, and it brings no sugar for oral bacteria to ferment into further acid. Laboratory comparisons consistently place plain carbonated water far closer to still water than to soft drinks and fruit juice in erosive potential.

The genuine caveat is flavouring. A "sparkling water" with added lemon flavour usually contains citric acid, and citric acid is a real erosive agent — it lowers pH further and binds calcium out of the enamel surface. If your bottle has a flavour, read whether it has an acidity regulator too. Drinking with a meal rather than sipping across an afternoon reduces exposure whatever is in the bottle.

Bones, stomachs and the rest

The bone-density worry traces back to observational studies of adolescents drinking cola, and the candidate explanations there are phosphoric acid, caffeine, and the simple displacement of milk from the diet by something else. Carbonation is not the common factor: plain sparkling water carries no phosphoric acid, no caffeine and no sugar, and several sparkling mineral waters are among the better calcium sources on the shelf.

Digestion is the area where individual response really does diverge. Carbon dioxide released in the stomach distends it, and distension both relieves and provokes depending on the person: some people find sparkling water settles fullness and speeds gastric emptying, others find it triggers reflux or bloating. Nobody can tell you which you are from a page; a week of paying attention will.

For hydration purposes, sparkling water counts exactly as still water does. The gas is not doing anything to the fluid balance.

Analyses: the figures each producer publishes on the label or in its technical sheet — see the basis line on every water page. Reference intakes: EFSA Dietary Reference Values. Label claims: Directive 2009/54/EC, Annex III. Mineral-water constituent limits and the fluoride labelling rule: Directive 2003/40/EC. Tap-water parametric values: Directive (EU) 2020/2184. Checked 2026-09-06.

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