There is, of course, a cost to every fun thing.

Even when it’s unflavored, fizzy water contains an acid—carbonic acid—that gives it its bubbles. That acidity can gradually wear away tooth enamel.

The good news is, it’s a relatively weak acid. Unless they’re flavored with citric or other acids, seltzers tend to have more neutral pH values than soft drinks like Coke. While bottled flat water has a pH of about 7—or totally neutral—that of Perrier is about 5.5.

The flavorings, though, can bring the pH down, making the beverages even harsher on tooth enamel. One 2007 study in which researchers exposed human teeth to flavored sparkling waters for 30 minutes found the waters to be roughly as corrosive as orange juice. “It would be inappropriate to consider these flavored sparkling waters as a healthy dental alternative to other acidic drinks,” that study concluded.

Yikes. When I read that, I decided to go cold-turkey. But first, I ran to my SodaStream, which gently farted out one last bottle of diet ginger ale, for a rainy day.

I also emailed Damien Walmsley, a professor of dentistry at the University of Birmingham in England, hoping he would give me an answer I liked better.

“There is a theoretical risk of tooth erosion, but the drinks would have to be consumed over a long period of time,” he said. (How long are we talking here, Damien? I got through grad school on little else but Pellegrino and frozen yogurt.) “My advice is to keep acidic drinks to meal times, and if you have to sip drinks between meals, then plain water is the safest.”

The good news is that La Croix and its ilk are still likely far less damaging to teeth than regular soda. (And one study of various colas, even, found that their exact pH level was only weakly correlated to their corrosive potential.) If you’re drinking unsweetened seltzer, you’re doing better than the avid Dr. Pepper guzzler—at least as far as cavities go.

The amount of seltzer you can safely drink without risking Joker mouth also depends on individual factors, such as how much acid and sugar you consume in your regular diet, your history of cavities, and whether you get enough fluoride from tap water and toothpaste, according to Andrew Swiatowicz, a dentist in Wilmington, Delaware.

“For an average, healthy person, carbonated, sugar-free beverages are not going to be a main cavity-causing factor,” he said. “If you are at all concerned, you can always dilute the carbonated water with regular water, or even just swish with regular water after.”

Got it. Will definitely swish with regular old club soda after my last La Croix of the night.