At this point, we can only hope for no more heat waves like the ones we’ve had to endure this summer. Even “a little cooler by the lake” has been little consolation this year, especially once you factor in humidity.
All the more reason to stay hydrated.
Ideally, you’ve been doing that with plain water. Your body needs it, and nothing quite beats it. But we know it can be a little boring for some. A little flavor and some bubbles can get a person drinking more water — and that especially matters at times when extra hydration is needed.
But maybe you’ve seen headlines or social media posts about how sparkling water can damage your tooth enamel just like soda because it’s acidic.
Certainly, sparkling water is more acidic than flat water. That’s because of the carbonation. Adding carbon dioxide to water creates carbonic acid, lowering the pH. The question is how much of a difference that makes to your mouth.
New research out of Purdue University offers some perspective.
Presented earlier this summer at NUTRITION 2026, the study compared four beverages: plain water, unsweetened sparkling water, calcium-fortified unsweetened sparkling water, and sugar-sweetened soda. The researchers first tested the pH of the drinks themselves, then had participants drink 12 ounces of each beverage over 10 minutes. Their salivary pH was measured before, during, and after each beverage.
In the lab, the results were about what you’d expect. Soda was the most acidic, followed by regular sparkling water, calcium-fortified sparkling water, and finally plain water.
That difference matters. Many sodas and other acidic drinks have a pH between 2 and 3. Plain carbonated waters tend to be considerably less acidic. And because the pH scale is logarithmic, a difference of even a couple of points represents a very large difference in acidity.
But then there’s what happens once you actually drink them.
In the study, regular unsweetened sparkling water caused only a small, short-lived change. Salivary pH was significantly lower than with plain water at only one point: two minutes after participants started drinking. After that, the difference disappeared.
Soda was another story. It caused the biggest drop in salivary pH. Even 20 minutes after drinking, there was still a significant difference from plain water. Although none of the beverages pushed overall salivary pH below 5.5, the threshold the researchers used for enamel demineralization, the soda clearly presented the greater acid challenge.
And that’s no surprise, really. While carbonation means both sparkling water and soda contain carbonic acid, soda contains other acids, as well — typically phosphoric or citric acid. Regular soda adds sugar on top of that, giving oral bacteria fuel to produce even more acid.
That’s what you’d call a triple whammy.
Of course, once you take a sip, your mouth gets involved, too. One of saliva’s jobs is to dilute and clear acids. Its natural buffering action brings oral pH back toward normal. That helps explain why sparkling water’s effects didn’t last long. Being less acidic than soda, the saliva had less work to do.
Now, this study was small — just 12 participants completed it — and it looked only at short-term changes in salivary pH. So it hardly settles every question about sparkling water’s effect on enamel.
What it does do is help put the risk into perspective.
Yes, carbonation makes sparkling water more acidic than flat water. If you’re choosing between them purely for your teeth, plain water still has the edge. But if bubbles make water more appealing and help you drink more of it, unsweetened sparkling water is a better choice than soda.
And if it’s flavor you’re after, you don’t necessarily need to buy it already flavored..
Infusing your own still or sparkling water lets you know exactly what’s going into it, and there’s plenty to play with beyond the usual squeeze of lemon or lime. Try cucumber with mint or basil. Add strawberries, raspberries, blueberries, peaches, or watermelon. Fresh ginger adds a little bite. Herbs such as mint, basil, rosemary, thyme, or even a little lavender can add plenty of flavor on their own.
You can mix and match, too: strawberry and basil, peach and ginger, cucumber and mint, watermelon and rosemary, raspberry and mint. You don’t need much. A little fruit, a few slices of cucumber, or a sprig or two of fresh herbs can make a glass or pitcher of water much more interesting.
Citrus is certainly an option, too, but there’s a reason not to make it the automatic choice every time. Lemons, limes, oranges, and grapefruit bring acids of their own. If you’re sipping strongly citrus-infused water throughout the day, you’re giving your teeth more frequent acid exposure, which kind of defeats the purpose.
So bring on the bubbles. Throw in some berries or cucumber. Raid the herb garden. And eventually Wisconsin will turn the thermostat down.
