The smell in the basement of Jeff Weaber’s farmhouse might make most noses crinkle: It’s tangy, sweet-and-sour, yeasty. And it’s informative: When Weaber wakes up in the morning and goes downstairs for breakfast, the aroma drifting up through the floorboards can alert him that a brew is ready for bottling. The smell, he says, “goes from being sweet as it turns into acids. I can walk into the kitchen and [think], Hey, these are ready to go.”

Weaber is talking about the stainless-steel pots lining the wooden shelves in his brick-walled cellar. The “brew” inside them is not beer, but aging kombucha in various stages of fermentation. When that process is complete, both Weaber and his brewer, Mike Kin, know it. “It’s sort of a high, sharp note, a little bit that your nose picks up,” says Kin. Cryptic codes scrawled on a white board remind him when he started each batch.

The kombucha in the pots begins as a blend of brewed green and black teas, to which Kin adds sugars. Which kinds of sugar, and how much, are proprietary secrets that have probably helped Weaber’s company, Aqua Vitea Kombucha, thrive.

After each batch of tea is amply pumped with sugar, Kin adds the kombucha culture — a white, rubbery pancake descended from the “mother” that reportedly dates back to third-century China. The culture, which also goes by the acronym SCOBY (for symbiotic colony of bacteria and yeast), devours the sugars in the tea over two to three weeks. This ultimately produces a tangy, slightly effervescent drink that devotees swear improves digestion, enhances the immune system and helps the body detoxify.

During fermentation, another SCOBY forms on top, ready for the next batch — but it must be fed, or it will die. “The culture is constantly regenerating,” says Kin.

If you’ve ever sipped a kombucha, you probably haven’t forgotten your first impression; some pour the rest down the drain, while others are hooked immediately, regardless of the “fuzz” floating in their drink. Depending on your palate, the taste can resemble that of sparkling cider or fizzy vinegar.

When Weaber first tasted kombucha, he was working as a brewer at the Lucky Labrador Brewing Company in Portland, Ore. His soon-to-be wife, Katina Martin, was in training to become a naturopath, and her focus on the medicinal properties of food inspired Weaber to reconsider his career. He began reading about kombucha and its fermentation process before he had even tried it.

So, the day Weaber wandered into a nearby health-food store and encountered a kombucha tasting station, he was primed. “I was extremely overwhelmed by this intense, sharp and dry flavor, but was eager for another try,” he recalls. “What I remember more than the taste was the overall sense of well-being I experienced for the rest of the day.”

At Weaber’s brewery job, he’d often start sampling beer by 7 a.m., and then relax in the evening with another bottle from the Kegerator on his porch. One summer evening, he realized he had skipped the beer and was drinking just kombucha. Soon Weaber began applying his brewing and chemistry acumen to making his own batches. He started stocking that Kegerator with beer and homemade kombucha.

“Sometimes you feel like there are holes [in your body]; kombucha was filling those holes,” Weaber says. He’s referring to the brew’s ballyhooed adaptogenic effect, the assertion that kombucha finds weaknesses in your body and corrects them — lowering blood pressure, easing digestion and detoxifying the organs.

Though kombucha hasn’t received much scientific study, its popularity as a health elixir has persisted through the ages and across continents. Called by various names depending on location — kocha kinoko in Japan, kvass in parts of Russia — it remained prevalent until World War II, when black tea (or grain) and sugar became too scarce for households to keep feeding their cultures. Kombucha began to appear in the U.S. about 15 years ago as a health drink — some call it a “functional beverage” — easily brewed at home. Commercial brewers such as Synergy Drinks soon jumped into the arena. The market for kombucha and other functional drinks was valued at around $295 million in 2009, according to market research firm SPINS.

If the health claims made by the drink’s passionate supporters are not yet proved by double-blind studies, basic chemistry does back them up: Kombucha fermentation creates a soup of vitamins, amino acids and bacteria (probiotics) that is known to be beneficial. The fermentation also renders trace amounts of both caffeine and alcohol, usually less than 1 percent. You’d need to drink dozens of bottles to get a buzz. Even so, Whole Foods Market decided to pull kombucha from its shelves last summer, and companies such as Honest Tea have discontinued their production of the stuff until labeling issues are worked out. Brewers now need to demonstrate that they can keep their kombucha’s alcohol content under 0.5 percent, or it must be labeled an alcoholic beverage.

In 2005, Weaber and Martin moved to Vermont to be closer to family, and bought an idyllic, 15-acre farm in Salisbury. In their restored yellow farmhouse, Martin — now a naturopathic doctor — established an office upstairs, while Weaber commandeered the basement for his kombucha operation. He uses the farm’s spring water for brewing, and named his company Aqua Vitea Kombucha as a tea-based twist on the Latin phrase for “water of life.”

Weaber and Martin began selling their product — a flavor now dubbed Original — at farmers markets in 2007; their success encouraged them to approach natural-foods markets and co-ops. Weaber initially offered the kombucha — which is 95 percent organic and NOFA certified — in 5-gallon kegs with taps, so it could be sold in bulk. The company gradually began bottling it, too, and added flavors tied to the seasons: a gentle, fruity (and antiviral) elderberry in winter, with berries sourced from Québec and Ferrisburgh’s Honey Gardens Apiaries; a zesty ginger in summer, with flavor from the Ginger People in California; an apple cider in fall, with fruit from Weaber’s neighbors, as well as puckery cranberry and spicy mulled cider.

John DiCarlo, co-owner of Sunflower Natural Foods in Waterbury Center, grabbed one of Aqua Vitea’s cards at the Rochester Farmers Market during the drink’s early days there, and installed a tap in his store when that option became available. “I liked the fact that [the kombucha] was a local one,” says DiCarlo. He started imbibing the stuff himself — perhaps a little too much. “When you start to drink it, you can go overboard,” says DiCarlo, who didn’t want to get hooked. “I’ve definitely tapered down on it a little.”

Another early fan was Raechel Barone of On the Rise Bakery in Richmond, who installed kombucha taps two years ago and loves the drink’s versatility. “Last year, we juiced our watermelons, and [Aqua Vitea] brought us some plain kombucha. We opened up the keg, and, though it was hard to get a good mix, it was really, really good, and really popular,” she says, describing the unwieldy process of blending the watermelon juice into the keg.

The beauty of the self-serve fountains, according to both DiCarlo and Barone, is that they enable people to reuse their own containers. Weaber estimates the company has saved 20 tons of glass so far. DiCarlo has also noticed another phenomenon: customers switching from booze to kombucha. “It has a niche in helping people to drink less alcohol,” he says. “I’ve found that many people have cut down on their beer and wine and drink kombucha instead.”

This may explain why drinkers can now find kombucha on tap at Nectar’s in Burlington.

Mike Kin, who was a close friend of Weaber’s in Oregon — and whose paintings adorn Aqua Vitea’s colorful labels — moved to Vermont with his family two years ago to become the company’s brewer. He tends to a product now sold in 50 places throughout Vermont, Massachusetts and New York, with 20 fountains in all. Sales have doubled in each of two consecutive years, says Weaber, and the company is on track to accomplish the same feat this year.

Given his multiplying taps and customer base, and his deepening commitment to healthy drinks, last year Weaber started thinking about making and selling herbal iced teas. He may have been inspired by his close friendship with another local liquid enthusiast, John Wetzel of Middlebury’s Stone Leaf Teahouse.

Weaber and Martin were selling kombucha at the Middlebury Farmers Market in 2007 when they met Wetzel. He had traveled far and wide tasting and sourcing teas, first for Burlington’s Dobrá Tea Room (which he helped found) and later for Stone Leaf, so he was a natural go-to man for Weaber’s next idea.

Weaber and Wetzel began playing with brews, but quickly found that herbal iced tea doesn’t keep well in the long term. “So we sort of scrapped the idea for a while,” says Weaber. “Then I thought, What if we add kombucha to the tea? It acts as a natural preservative.”

The two men experimented with adding concentrated, trace amounts of kombucha to various herbal teas, finessing varietals of white and green teas and herbs. They began to pick up subtle differences based on steeping temperatures and times, as well as the water they used. “We played a lot with the balance [of tea and kombucha],” says Weaber. They found that the kombucha clarifies the tea and lends it a subtle piquancy.

In the end, three brews made the final cut. Rooibos, a robust tea handpicked in South Africa, yields an ocher-colored and fruity-tasting beverage with caramel undertones. The Ginseng Oolong is laced with licorice, rendering it the tangiest and most distinctive of the trio. The pale-gold Jasmine Pearl tastes faintly of the southern Chinese jasmine blossoms in the blend.

“It was the kombucha that brought the harmony” to all three blends, says Weaber.

The line of cultured teas debuted this spring, and Weaber hopes it will find its way into gas stations and convenience stores, as well as natural-food outlets. “There aren’t really a lot of grab-and-go choices that are healthy for you,” he says.