Does Sparkling Water Hydrate You as Well as Still Water?
Share
Yes — plain sparkling water hydrates you just as well as still water. The carbonation is only dissolved carbon dioxide gas; it does not change how much fluid your body takes in or holds on to. In a landmark study that ranked 13 common drinks by how well each kept people hydrated, sparkling water scored essentially the same as still water, retaining fluid just as effectively over the hours after drinking it (American Journal of Clinical Nutrition). So if unflavored seltzer is what gets you to drink more, it counts every bit as much as flat water toward your day.
Where the myth comes from
The idea that fizzy water is somehow "less hydrating" is intuitive but unfounded. People assume the bubbles, the slight acidity, or the tingle must be doing something — or they lump plain seltzer in with soda, which is a different drink entirely because of its sugar. Plain sparkling water is just water with carbon dioxide dissolved under pressure; pour it out and let it go flat and you are left with ordinary water. There is no mechanism by which the dissolved gas would reduce how much fluid you absorb, and the measured evidence backs that up.
What the hydration research found
The most useful evidence comes from the study that created the beverage hydration index, which had 72 men drink a liter of each test beverage and then measured urine output and fluid balance for the next several hours. Sparkling water landed right alongside still water, with a hydration index of about 1.0 — meaning it kept people hydrated just as well as plain water did (American Journal of Clinical Nutrition). Interestingly, the drinks that edged out plain water for fluid retention were ones with a bit of sodium or nutrients — like milk and oral rehydration solution — not anything to do with bubbles. For everyday hydration, still and sparkling are interchangeable.
The taste factor that actually matters
If the bubbles change anything, it is in your favor. For a lot of people, plain still water is boring and sparkling water is more enjoyable, which means they drink more of it — and the single biggest driver of good hydration is simply drinking enough. A beverage you reach for beats one you don't. So if switching to seltzer nudges you from "not enough water" to "plenty," that is a real, practical win, even though ounce for ounce the two hydrate identically.
The two caveats worth knowing
Two honest footnotes. First, sparkling water is mildly acidic, so sipping it constantly all day long can, over time, contribute to enamel wear — drinking it with meals and not nursing it for hours keeps that minor. Second, the carbonation makes some people bloated or gassy, and it can aggravate reflux or an easily upset stomach; if that is you, still water may simply feel better. Neither of these is about hydration — they are comfort and dental notes, and for most people they are easy to manage.
A note on flavored and sweetened versions
All of this applies to plain, unsweetened sparkling water. The moment a drink has added sugar — regular soda, tonic water, sweetened sparkling drinks — you are adding calories and, with sugar, a different beverage profile altogether. Unsweetened flavored seltzers are generally fine and still hydrate like water, but it is worth a glance at the label so "sparkling water" doesn't quietly become "soda." Keep it plain or unsweetened and the hydration math stays simple.
However you like your water, keep it cold
Still or sparkling, water is easiest to drink when it is cold and within reach. The NuRich 32 oz Insulated Water Bottle ($29.99) keeps a big serving cold for hours, while the NuRich 18 oz Insulated Water Bottle ($14.99) is the grab-and-go size for topping up on the move. Browse the full lineup at the NuRich collection.
The bottom line
Sparkling water hydrates you just as well as still water — the research puts them at the same point on the hydration index, and the bubbles are only dissolved gas. If seltzer helps you drink more, it is a genuinely good choice. Just keep it plain or unsweetened, be mindful of the mild acidity on your teeth, and switch to still if the fizz upsets your stomach. Otherwise, drink whichever you enjoy and count it fully toward your day.
This article is for general informational purposes only and is not medical advice. If you have reflux, a sensitive stomach, or dental concerns, consult a healthcare professional about what is right for you.