How to Brew Your First Batch of Kombucha
If you’re reading this, you probably already know what kombucha is, but you might not know what kombucha is, if you know what I mean. Maybe you were feeling experimental when you first grabbed a bottle of GT’s Trilogy, and perhaps you were intrigued by the curiously tart and fizzy experience it afforded you, but you probably didn’t think too hard about what goes in to making this weirdo beverage in the first place—or whether you, yes you, could participate in the process yourself.
Kombucha is a fermented drink made from sweetened tea—usually black tea, although you can also find versions that use green, or oolong, or even pu-erh tea. The important bit here is that it uses actual tea, from the tea plant. Advanced brewers will sometimes experiment with herbal infusions, but traditionally kombucha is made from brewed tea, sugar, water, and a SCOBY (more on that in a moment).
Kombucha has been around a very long time; its earliest documented appearance is all the way back in 221 BCE in China, where it was consumed as a health drink. Even today, kombucha is alleged to have profound abilities to cure a litany of illnesses, from cancer to diabetes. Unfortunately, there’s almost no science to support these assertions. The one thing most reputable science types do tend to agree on is that, like many fermented foods, kombucha is chockablock with probiotics, so it seems likely that drinking it might offer similar benefits to any probiotic consumption—mainly a well-balanced gut microbiome and a more, uh, regular bowel situation.
Personally, I drink kombucha because I like the way it tastes, and I’ve also had some good times experimenting with flavors. If you’re looking to kombucha for potential healing properties, I won’t tell ya no. I’ll just say that kombucha, or any food or beverage, is not medicine, so I’d suggest you only consume it if you genuinely like it. Home-brewed kombucha is a very different creature than the store-bottled kind, so even if you’re not a fan of commercial kombucha, you might really dig what you can make yourself.
Get to know the SCOBY gang
Let’s talk about the SCOBY, the coolest part of kombucha-making. SCOBY stands for “Symbiotic Culture of Bacteria and Yeast.” To be frank, it looks like something a gravely ill elephant would sneeze at you, but you need to make peace with handling a giant snotty blob if you’re going to give kombucha-making a go.
It took me a while to get comfortable with the kombucha process, and putting my hands on this slippery-spongy colony of organisms was a big part of why. But, mucus-y vibes notwithstanding, a SCOBY is the beneficial microbial mat that does all the real work after you’ve prepared its lovely little tea bath. The cultures in the SCOBY eat the sugar in the sweet tea and convert it into acids, carbon dioxide, and a bit of alcohol. It’s also sometimes called a “mother,” and it’s similar (but not quite the same) to the filmy muck you see in a bottle of unfiltered apple cider vinegar. (It’s also sometimes called a “mushroom,” but that’s just plain wrong.)
The SCOBY may not adhere to cultural beauty standards, but over time I’ve come to think of her as beautiful; she’s plump and healthy and ferments my sweet leaf juice. I’m not saying I talk to mine sometimes, or give her little appreciative pets, but I’m not not saying any of that either.
Where do you get a SCOBY of your own? These days you can buy them online, but you might be able to source one locally. One of the first kombucha-making books I read said something like, “You might be surprised to learn that someone you know makes kombucha!” and I was like “Shut up book, you don’t know my friends.” But then it turned out that a local friend did make her own kombucha, and she had an extra SCOBY to pass off to me. Book 1, Lesley 0.
The SCOBY reproduces as part of the kombucha process, so the original SCOBY you pop in the vessel grows a new SCOBY as a second layer at the surface. Each batch equals one new SCOBY to make your next batch of kombucha! You can compost the extra, make a SCOBY hotel to keep them in long-term, or become your town’s Kombucha Fairy and deliver baby SCOBYs to all the hopeful home brewers in your neighborhood. (Some folks apparently use extra SCOBYs to make skincare products. That’s way beyond my own interests, but maybe it appeals to you.)
Don’t screw the ‘booch
Before we get into the process, we’re going to have a little chat about food safety. Like all forms of home fermentation, kombucha comes with a certain degree of risk, as it’s much more challenging to prevent contamination in a home kitchen compared to the stricter regulations of a commercial space.
That said, kombucha has never conclusively been attributed to an outbreak of foodborne illness. There was one documented 1995 case in which a person may have died, and it’s this story that usually comes up when discussing kombucha’s potential risks. But all medical efforts to determine a cause in that case came up empty, and the two ill people seemed to only have one possible factor in common—they had both been drinking homebrewed kombucha made with SCOBYs sourced from the same local supplier. Over a hundred other people had also gotten SCOBYs from the same place without mishap, so it’s not actually a sure thing that the kombucha was the cause, but the incident was scary enough that it put a bit of a pall over kombucha safety for a long time.
The current conventional advice is that pregnant or nursing people, as well as people with weakened immune systems, should avoid kombucha, but the evidence supporting this is not super conclusive, and it may be a matter of erring on the side of caution. Similarly, the CDC suggests drinking no more than four ounces a day, which is not a lot of kombucha (your typical store-bought bottle holds 16oz). I am hardly prepared to contradict the CDC, but I will say that your personal kombucha consumption should be determined by what feels best for your own body. Pay attention to how kombucha hits your guts and decide how much is enough for you.
This is probably also a good time to note that one of the squirrellier parts of home kombucha brewing is the wildly unpredictable alcohol content. Yes, part of the fermentation process involves the production of alcohol. Commercially-available kombucha needs to have an alcohol content below 0.5% ABV; otherwise it has to be labeled and sold as an alcoholic beverage, which obviously has a profound impact on how it goes to market. (Back in 2010, Whole Foods pulled all kombucha from its shelves after tests revealed higher alcohol content than expected).
Home brewed kombucha is unlikely to get above 2% ABV under normal circumstances—for comparison, beer can range from 3% to 13% ABV—but that’s an important distinction for folks who are avoiding alcohol. Also, while strategies exist for making “drunk kombucha,” it’s not easy to control with precision, whether you want to boost your ABV, or minimize your buzz as much as possible. Point being, if you’re sensitive to booze, you might want to try a different hobby.
The mighty ‘booch
Enough talking. Let’s get brewing. To make one gallon of kombucha, here’s what you’ll need:
- One gallon of dechlorinated water (filtered or bottled is also fine)
- Five standard size black tea bags (organic if you’ve got ‘em)
- One cup white sugar
- A SCOBY
- At least one cup of unflavored mature kombucha (store-bought is fine)
And for your tools:
- A brewing vessel that holds at least 1.25 gallons with a wide top opening
- A clean tea towel
- A non-reactive stirring implement
- Swing top bottles for storing your finished kombucha (I like these)
- A funnel for filling those bottles
- pH strips (or a pH meter if you have one handy)
- A food thermometer and/or a stick-on thermometer (optional, but useful)
First things first: Make the tea. Bring one quart of the water to boiling, then turn off the heat, move the kettle off your burner if it is electric, and plunk in your tea bags. These can steep anywhere from five to 15 or even 20 minutes, depending on how strong you like your brew.
While your tea is steeping, this is a good time to make sure your brewing vessel is clean, clean, clean. Using antibacterial soap might sound like a good idea, but don’t—it can leave residue that may impede your brew. Use very hot water and/or a 50/50 mixture of distilled white vinegar and water instead. I usually do a final vinegar rinse right before I start loading the brewing vessel up, just to be sure it’s well prepared to host my future kombucha.
While there are several different types of brewing vessels, I strongly suggest going with a glass one. For one thing, ceramic vessels must have a kombucha-safe, food-grade glaze, and that kind of info isn’t always available from every supplier. Also, at least until you’re used to the process, it’s helpful to be able to see what’s happening from day to day.
Pour the other three quarts of room temperature water into your vessel. By now your tea should be done brewing, so dump those teabags in the compost. Add the cup of sugar to the tea, stirring until it’s completely dissolved. Do not try to make diet kombucha by using less sugar or substituting some other sweetener, as the SCOBY requires a certain amount of sugar for fermentation to occur. Also, use plain old refined white sugar until you have gained more experience; using raw sugars might be fun later on, but that’s the kind of advanced move that can produce unpredictable results.
Let the tea concentrate sit to cool a bit. When you’re ready (and the sugar is fully dissolved), pour the tea into the vessel with the rest of the water. With a clean finger, test the temperature. If it feels much warmer than body temperature, throw the tea towel over the top and let it cool further. If you have a thermometer handy, aim to get it below 100℉—any warmer than that risks harming your SCOBY.
When it feels right, take those clean hands and drop in the SCOBY. Once the SCOBY is in the vessel, pour a cup or two of mature kombucha on top. “Mature” or “strong” kombucha is kombucha that has been fully brewed; if you don’t have access to fresh unflavored kombucha, you can use store-bought kombucha instead—just make sure it’s unflavored. Your SCOBY may sink at this point; if it does, don’t worry, it’ll still work.
Put the clean tea towel over the top of the jar. Air needs to circulate, so whatever fabric you put over the top should be permeable, but you don’t want too loose a weave, as your evolving kombucha will smell fantastic to any insects in your house (don’t use cheesecloth, is what I’m saying). I like to secure the tea towel with a rubber band or some string just for extra certainty.
At this point you can move the whole shebang to a warm-ish spot that’s well out of direct sunlight where it’s unlikely to be disturbed. An ambient temperature of 75℉–85℉ is great, but kombucha will still brew at cooler temperatures, it will just take longer; that stick-on thermometer I mentioned above applied to the side of your vessel is helpful here.
And now: Wait. Your kombucha will get to fermenting, and the flavor will depend on how long you let it go. You’ll start to see the baby SCOBY forming at the surface like a blanket, and it will get thicker the longer you let it brew. At around five to seven days, you can begin testing by gently dipping a clean spoon or glass along the edge of the SCOBY to get a sample.
Before you try a brand new batch, I forcefully recommend pH testing it. Paper test strips are cheap and easy and can confirm your brew has reached a safe acidity; for basic kombucha you should expect a pH between 2.5 and 3.5, which is acidic enough to prevent the growth of most forms of undesirable (and dangerous) bacteria.
The first taste of your own kombucha is pretty magical. As long as your pH is within range, you can bottle your batch whenever it reaches the flavor you like best; early kombucha is sweeter, while later kombucha becomes more tart. When you’re ready, you can bottle it as-is, or bottle it and add flavoring agents, and then give it a shorter secondary fermentation period at room temperature to generate more complex flavors and create a bit of fizz in the enclosed bottles.
You can flavor kombucha with almost anything you want—herbs, spices, ginger, syrups, fresh fruit, or even jam—but the total volume of flavoring agents should be five percent or less of the bottle volume. This doesn’t sound like much, but I’ve learned a little flavor goes a long way. Add your flavors and then fill the bottle with kombucha, leaving some headspace at the top. I recommend using swing-top bottles for convenience. You can leave the flavored bottle out for a day or three, depending on temperature, for a secondary ferment, but after that, pop it in the fridge so the process is throttled—hopefully before the brew gets too strong or acidic for your palate. (Warm temperatures accelerate fermentation; cool temperatures slow it down.)
A warning: If you add flavoring agents with sugars in them, this will restart the fermentation process, except now you’ve got that process trapped in a sealed bottle. Developing carbonation is a tricky balance that requires your conscientious attention. Refrigerating your kombucha will slow this down, but it’s wise to periodically “burp” any sealed container you’ve used to store kombucha. I scoffed at others’ stories of exploding bottles (because I’m a dumb jerk!) until a bottle on my counter exploded mere moments after I’d left the kitchen. Luckily that situation turned out fine, but believe me, kitchen cockiness does not prevent explosions.
And that’s it—you’ve made your first batch! There are additional processes for doing continuous kombucha brewing, and loads of options for mad scientist-worth flavor experiments, but that’s beyond the purview of this post. You can check out one of the many excellent books on the subject to push your brewing journeys ever further—I like The Big Book of Kombucha by Hannah Crum and Alex Lagory as a beginner guide.
Now you can sit back with a glass of your own fresh kombucha, give your SCOBY a grateful pat (wash your hand first!) and feel the deep satisfaction of having spent weeks making at home what you previously depended on Whole Foods to provide. It’s called “self-reliance,” and it tastes so good.