Sparkling water hydrates just as well as still water. In a clinical trial published in The American Journal of Clinical Nutrition, researchers measured urine output over four hours after participants drank sparkling water versus still water and found no difference in fluid retention between the two. The carbonation doesn’t change how your body absorbs or holds onto the water.
How Sparkling Water Compares to Still Water
The beverage hydration index, developed to rank drinks by how well they keep you hydrated, treats sparkling water and still water as essentially identical. Both have the same water content (100%), and the body retains the same amount of fluid from each. The carbon dioxide gas that creates the bubbles escapes your body quickly and doesn’t interfere with absorption.
One concern has been whether carbonation speeds up or slows down how fast fluid leaves your stomach. Research on this is reassuring: while higher carbonation levels temporarily expand the stomach in the first 20 minutes after drinking, this doesn’t translate into meaningful differences in how quickly the fluid empties from the stomach or enters your bloodstream.
One Catch: Carbonation Can Make You Drink Less
The fizz in sparkling water does increase feelings of fullness. In a study published in The British Journal of Nutrition, people who drank beverages with medium or high carbonation felt significantly more satiated than those who drank low-carbonation versions. Separately, when people were allowed to drink as much as they wanted after exercise, their total fluid intake dropped progressively as carbonation levels increased.
This is the most practical concern with using sparkling water for hydration. If you’re trying to rehydrate after a workout, during illness, or in hot weather, the bubbles may make you feel full before you’ve replaced enough fluid. In those situations, still water lets you drink larger volumes more comfortably. For everyday hydration throughout the day, though, this effect is minor, and many people actually drink more total fluid when they enjoy the taste of sparkling water.
Not All Sparkling Water Is the Same
The term “sparkling water” covers several different products, and their mineral content varies enough to matter.
- Seltzer water is just water with added carbonation. It contains no sodium or potassium.
- Club soda has added minerals: a 12-ounce serving typically contains about 75 milligrams of sodium and 7 milligrams of potassium. The small amount of sodium can actually aid fluid retention slightly, similar to how sports drinks work.
- Mineral water contains naturally occurring minerals that vary by brand. Some brands carry up to 1,000 milligrams of sodium per serving, which is nearly half the daily recommended limit of 2,300 milligrams. Drinking that amount all day could be a problem for people watching their sodium intake.
If you’re choosing sparkling water specifically for hydration, check the label. For most people, plain seltzer or lightly mineralized options are the simplest choice.
Digestive Comfort Matters
For some people, sparkling water causes enough gas and bloating to make drinking it uncomfortable, which indirectly works against hydration if it discourages you from drinking. People with acid reflux or GERD are more likely to experience this. Drinking through a straw can make the bloating worse by introducing extra air.
If carbonated water consistently makes you feel uncomfortable, switching to still water removes a barrier to staying hydrated. There’s no hydration advantage to the bubbles that would justify pushing through the discomfort.
Dental Health With Regular Use
Plain sparkling water is more acidic than tap water, with most brands falling below a pH of 5.5. Lab studies show that carbonated beverages cause more surface roughness and volume loss on tooth surfaces than noncarbonated ones. In practice, though, the acidity of unsweetened sparkling water is not high enough to harm dental enamel for most people at moderate intake levels. The risk increases if sparkling water is your only source of fluids throughout the day, because the repeated acid exposure adds up over time. Mixing in regular water spreads out that exposure.
The Bone Density Question
You may have heard that carbonated drinks leach calcium from bones. This concern comes from research on cola specifically, not carbonation in general. The Framingham Osteoporosis Study found that cola consumption was associated with lower bone mineral density in older women, but no such link existed for other carbonated beverages. Plain sparkling water does not affect bone health.
When Sparkling Water Works Best
Sparkling water is a reliable hydration source for daily use. It counts fully toward your fluid intake, and if the taste motivates you to drink more water than you otherwise would, it’s doing you a favor. Where it falls short is in situations demanding rapid or high-volume rehydration, like after intense exercise or during a stomach illness, where the fullness from carbonation can limit how much you take in. In those moments, flat water or an electrolyte drink lets you replenish faster. For everything else, the fizz is fine.