Is sparkling water as hydrating as still water?
Yes. In the 2016 beverage hydration index study (Maughan et al., Am J Clin Nutr; PMID 26702122), sparkling water scored 0.99, where still water is the reference at 1.00. The tiny difference was not statistically significant, meaning the two hydrate equally. Both sit at the centre of the beverage hydration index, alongside coffee, tea, and most everyday drinks.
Does carbonation affect hydration?
No. The bubbles in sparkling water are dissolved carbon dioxide — a gas that escapes as you drink and digest, rather than staying in the body or changing how water is absorbed. What determines a drink's hydration is its water content and what is dissolved in it, such as sodium or sugar. Plain carbonation adds neither, so carbonated water behaves like still water for fluid balance.
Sparkling water, soda water, and club soda
Plain sparkling water, soda water, and club soda are all carbonated water, and all hydrate about as well as still water. Club soda and some mineral waters carry a little added sodium, which makes no meaningful difference to everyday hydration. The distinction that does matter is sugar: a flavoured, sweetened sparkling drink or a regular soda still provides fluid, but it also adds sugar and calories. The carbonation is never the issue — the sugar is.
Are there any downsides?
For hydration, none. Sparkling water does not dehydrate you. The only common complaints are practical: the gas can cause mild bloating or burping in some people, and plain carbonated water is slightly acidic — though far gentler on teeth than sugary, citric sodas. If you find still water boring, sparkling water is a fully equivalent way to meet your fluid needs.
