Active lifestyles are in vogue, and that same health-conscious demographic is starting to drive demand for beverages with “live and active” label proclamations that line up with guests’ adventurous spirits—specifically the live and active cultures found in fermented beverages like kombucha, kvass, and kefir. As with plenty of modern fascinations, fermented beverages have strong connections to old-world flavors and the DIY aesthetic, with many operators brewing them in-house or crafting small-batch flavors and quirky combinations.

For Cortney Burns and Nick Balla at San Francisco’s Bar Tartine, their first exposure to these sweet and sour, fizzy and far-out flavors came from their respective parents, who were simply serving up familiar food and drinks with ancient cultural roots. For Burns, that meant the fermented beet dishes that were part of the regional Jewish cuisine in Chicago; for Balla, who spent time in his childhood in both New York City and Hungary, it was sauerkraut and kvass from the local Russian market.

“We loved those flavors as kids and craved them and didn’t understand why we couldn’t have them in restuarants, because it was always just soda pop and things like that,” Balla says.

Now, the two are co-chefs at Bar Tartine, a restaurant and bakery where they sell beverages like rye, fennel, and beet kvass and dairy kefir with white peach and lavender. At least, that’s what’s on the menu this week—the specialty soft drinks are brewed in 10-gallon batches, and the flavors never repeat, always representing whatever seasonal fruits, vegetables, or herbs the team happens to have on hand. The kvass, which can be made from (among other things) boiling bread, is made from the output of Bar Tartine’s bakery, giving the drink menu that much more of a quality craft feel—and it taps into an interest in health and fermentation that Balla says goes far beyond just adventurous big-city clientele or high-brow diners looking for unfamiliar options.

Way down the California coastline in Carlsbad, guests flock to 83 Degrees’ pet-friendly patio and 14-television dining room for a game-day experience where they can enjoy new takes on American classics, plus a constantly changing craft beer menu, a glass of wine, or a classic cocktail. One more surprising thing they can also enjoy is the kombucha that is newly on tap, and the less-classic kombucha cocktails mixed up behind the bar (Kombucha Mule, anyone?), which general manager Nick Wheeler says are wildly popular. Initally, Wheeler—who is a non-drinker himself—had been searching for a non-alcoholic beer to put on tap when a sales representative suggested kombucha as a high-selling alternative.

“It was a hit! I went through more cases of kombucha faster than I could imagine,” Wheeler says. He now has two flavors constantly on tap. He adds that the kombucha cocktails sell much more than craft beer cocktails the team had tried in the past, which customers seemed to see as more of a novelty than a go-to. The new, tangy cocktails have also been useful for prompting interactions between servers and customers, something Wheeler has gotten in on himself. “The first thing I do for an undecided customer is explain the process, taste, and health benefits, and I can present them an alternative to traditional options that they can feel better about and really get interested in,” he says.

This old-meets-new movement toward fermented beverages presents an asset for operators and a godsend for customers—both of whom are looking for ways to add intrigue and healthy options to modern beverage menus.