Does Sparkling Water Hydrate as Well as Still Water?
Carbonation changes the fizz, not the hydration. In a controlled 72-person trial, sparkling water held its own against plain water, retaining fluid just as effectively over four hours.
Quick answer
Does Sparkling Water Hydrate as Well as Still Water?
Yes. In the Beverage Hydration Index trial by Maughan et al. (2016, Am J Clin Nutr), 72 men drank 1 litre of each beverage, and sparkling water's 4-hour urine output was not significantly different from still water — a hydration index of about 1.0. Carbonation does not reduce hydration, so sparkling water counts fully toward your daily fluid intake.
From the research to your daily target.
Vari turns the hydration science — how much water, what counts as fluid, which drinks hydrate best — into one personalised, sourced daily plan.
Get My Hydration Plan →Free trial • Takes 60 seconds
Built for iPhone · Apple Health sync · Weather-aware · Privacy-first
Sparkling water hydrates as well as still water. In the landmark Beverage Hydration Index (BHI) study by Maughan et al. (2016), 72 euhydrated, fasted healthy men each drank 1 litre of still water or one of 12 other beverages over 30 minutes, after which urine was collected for 4 hours. The BHI anchors still water at 1.00 and divides the urine output after water by the urine output after the test drink, so a value above 1.0 means a drink is retained better than water. Sparkling water was one of nine beverages whose cumulative 4-hour urine output was not significantly different from water — a hydration index of approximately 1.0. In other words, the carbon dioxide that makes water fizz does not measurably change how much fluid your body keeps. It counts fully toward your daily fluid goal, the same as plain water.
Sparkling Water vs Still Water in the Beverage Hydration Index
| Beverage | 2-hour BHI | 4-hour result vs water |
|---|---|---|
| Still water (reference) | 1.00 | Baseline anchor The BHI sets still water at 1.00 by definition; every other drink is measured against it (Maughan 2016). |
| Sparkling (carbonated) water | ~1.0 (not significantly different) | No significant difference Sparkling water's cumulative 4-hour urine output was not statistically different from still water, giving a hydration index of approximately 1.0 (Maughan 2016). |
| Skim milk (best in study) | 1.58 ± 0.60 | Significantly better than water For context, skim milk topped the index at a 2-hour BHI of 1.58 ± 0.60 thanks to its electrolytes and energy density of 350 kcal/L (Maughan 2016). |
What the Study Found About Carbonation
Statistically Equal to Water
Sparkling water sat in the cluster of nine drinks — alongside cola, diet cola, hot tea, iced tea, coffee, lager, orange juice and the sports drink — whose 4-hour urine output showed no significant difference from still water (Maughan 2016). Its hydration index was approximately 1.0.
No Beverage Scored Below Water
Not one of the 13 beverages tested — including coffee, tea and lager — had a BHI significantly lower than water. At a 1-litre dose, none caused net dehydration (Maughan 2016; ACE ProSource). Carbonation certainly did not push sparkling water below the line.
What Beats Plain Water
Only oral rehydration solution (BHI 1.54), skim milk (1.58) and full-fat milk (1.50) hydrated significantly better than water and stayed ahead through 4 hours (Maughan 2016). The edge comes from electrolytes and energy, not from the fluid being still or fizzy.
How BHI Is Measured
The index divides the urine output after still water by the urine output after the test drink, with water anchored at 1.00 (Maughan 2016). Less urine over the 4-hour window means more fluid retained — and sparkling water retained just as much as plain water.
Practical Takeaways for Sparkling Water Drinkers
- Plain sparkling water counts fully toward your daily fluid intake — it is as hydrating as still water (BHI ~1.0; Maughan 2016).
- If you find fizzy water easier to drink than flat water, that is a hydration win: the best fluid is the one you will actually consume.
- For everyday hydration, still and sparkling water are interchangeable; pick whichever you prefer.
- After heavy sweating, reach for an electrolyte-rich option — oral rehydration solution (BHI 1.54) or milk (1.50-1.58) retained fluid significantly better than either still or sparkling water (Maughan 2016).
- Choose unsweetened sparkling water to avoid added sugar; the carbonation itself does not affect hydration.
- Carbonation can make you feel full sooner, so sip steadily through the day if fizz curbs how much you drink in one go.
Calculate Your Daily Hydration Target
Sparkling or still, water counts. Get a personalized daily fluid goal based on your body weight, activity, and climate.
Use the Hydration CalculatorSources & Citations
- BHI ~1.0 (no significant difference vs water) — Sparkling water's cumulative 4-hour urine output was not significantly different from still water, giving a hydration index of approximately 1.0.[1]
- water = 1.00 (reference) — The Beverage Hydration Index anchors still water at 1.00; a BHI above 1.0 means a drink is retained better than plain water.[1]
- n=72; 1 L; 30 min; 4 h collection; 13 beverages — Study design: 72 euhydrated, fasted healthy men each drank 1 litre of still water or one of 12 other beverages over 30 minutes, with urine collected for 4 hours across a 13-beverage panel.[1]
- 9 beverages not different from water (BHI ~1.0) — Cumulative 4-hour urine output after sparkling water, cola, diet cola, hot tea, iced tea, coffee, lager, orange juice and the sports drink was not different from water.[1]
- ORS 1.54; skim milk 1.58; full-fat milk 1.50 vs water 1.00 — Only oral rehydration solution, skim milk and full-fat milk hydrated significantly better than water at 2 hours.[1]
- 0 beverages below water — No beverage tested had a BHI significantly lower than water; none caused net dehydration at the 1-litre dose.[2]
- [1]Maughan 2016 (Am J Clin Nutr) — Maughan RJ, Watson P, Cordery PA, Walsh NP, Oliver SJ, Dolci A, Rodriguez-Sanchez N, Galloway SD. A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index. Am J Clin Nutr. 2016 Mar;103(3):717-23.PMID: 26702122DOI: 10.3945/ajcn.115.114769
- [2]ACE ProSource — American Council on Exercise (ACE) ProSource, April 2016. The Newest Index on the Block: The Hydration Index (summary of Maughan et al. 2016).
Last reviewed: 2026-06-20. Every figure on this page is sourced to the named primary references above.
Want your exact hydration plan?
- ✓Study-backed targets
- ✓Every claim sourced
- ✓Tracks all beverages
💧 Quick Hydration Check
Get your estimated daily water need in 10 seconds.
Estimate only. Consult a doctor for chronic conditions (CKD, heart failure, etc.).
Frequently Asked Questions
Does sparkling water hydrate as well as still water?
Yes. In the 2016 Beverage Hydration Index study (Maughan et al., Am J Clin Nutr), sparkling water's cumulative 4-hour urine output was not significantly different from still water, giving a hydration index of approximately 1.0. The carbonation does not reduce how much fluid your body retains, so sparkling water counts fully toward your daily fluid intake.
Does carbonation reduce hydration?
No. In Maughan et al. (2016), sparkling (carbonated) water was one of nine beverages whose 4-hour urine output was statistically indistinguishable from still water. The dissolved carbon dioxide that creates the fizz had no measurable effect on fluid retention — its BHI was about 1.0, equal to plain water.
What is the Beverage Hydration Index (BHI)?
The BHI, created by Maughan et al. (2016), compares how well a drink is retained versus still water, which is anchored at 1.00. It is the urine output after water divided by the urine output after the test drink. A BHI above 1.0 means the beverage is retained better than plain water over the 4-hour measurement window.
How was the sparkling water hydration study done?
In Maughan et al. (2016), 72 euhydrated, fasted healthy men each drank 1 litre of still water or one of 12 other beverages over 30 minutes, after which urine was collected for 4 hours across a 13-beverage panel. Comparing urine output let researchers rank how well each drink, including sparkling water, was retained relative to plain water.
Which drinks hydrate better than plain water?
In Maughan et al. (2016), only oral rehydration solution (BHI 1.54), skim milk (1.58) and full-fat milk (1.50) hydrated significantly better than water and stayed ahead through 4 hours. Their electrolyte and energy content slows fluid loss. Sparkling water was not better than water, but it was just as good — about 1.0.
Is sparkling water bad for hydration?
No. No beverage in the Maughan et al. (2016) study — not even coffee, tea or lager — scored a BHI significantly below water, and none caused net dehydration at a 1-litre dose. Plain sparkling water sat right at the water baseline (about 1.0), so it is a perfectly good way to stay hydrated.
Can I count sparkling water toward my daily water intake?
Yes. Because sparkling water's hydration index was approximately 1.0 — statistically equal to still water in Maughan et al. (2016) — every glass counts toward your daily fluid goal exactly like plain water. Choose unsweetened versions to avoid added sugar; the carbonation itself has no downside for hydration.
You don’t need to track water manually.
Vari does it for you — personalized, weather-aware, Apple Health synced.
- ✓Smart reminders
- ✓Personalized plan
- ✓Apple Health insights
7 days free · Cancel anytime · iOS 15+
Track Every Glass, Still or Sparkling
Vari helps you log all your fluids and hit your personalized hydration target every day.