When Kati Aleckson is craving something sweet, she drinks a flavored sparkling water. When she needs an afternoon pick-me-up, she reaches for a caffeinated one. And when she’s out with friends, her go-to drink is hard seltzer.

The 29-year-old used to drink Dr Pepper during the day and hard cider on date nights. But she wanted to cut back on sugar and now drinks two or three sparkling waters a day. “It’s the fizz,” said Ms. Aleckson, who works at a Minneapolis nonprofit. “It kind of feels like a treat but not a bad treat.”...