Kombucha is an ancient drink made by using a particular bacteria and yeast culture to chemically transform sweetened tea. Here's the
Wikipedia page on Kombucha, and the
Wikihow page on making Kombucha.
There are all kinds of wild claims that it miraculously restores health -- or damages health. Here's a 1995 Paul Stamets article that has good info but is also biased
against Kombucha. I think he's misusing the precautionary principle by applying it to something that's been tested for thousands of years, and despite what he says at the end,
all the literature that I've seen mentions the possibility of contamination and methods for re-isolation. Personally I take only weak precautions to avoid contamination, I taste it straight from the jar, and I've never had a batch go bad. I think it's probably good for you, like other raw fermented drinks such as kvass and kefir.
Tools and Ingredients
It's generally believed that you need a starter
SCOBY, which stands for
symbiotic colony of bacteria and yeast. It's a tough, gelatinous, pancake-shaped, tan-colored thing that forms on the top of fermenting Kombucha. Sometimes it's called a "mushroom". Here's the
Worldwide Kombucha Exchange where you might be able to find one in your area free for pickup. You can also find them for sale online, and sometimes free on Craigslist.
My own experiments have found that you don't absolutely need a SCOBY -- you can bootstrap one if you can find some Kombucha drink with live cultures, which is sold at many natural food stores. Ideally, you should start with both a SCOBY and some live liquid.
Next you need clear
glass jar, at least one gallon (three or four liters) with a wide mouth. Metal and plastic will react badly with the acids in the Kombucha, and any ceramic that contains lead will leach it into the drink. It's tempting to use a crock pot, but some of them contain lead. I once used a two gallon fish bowl. The gallon jar I'm now using, I got at Grocery Outlet for $4, full of pickles that I composted.
Then you need a
big pot, stainless steel or ceramic, to make the tea in, a source of
pure water (filtered, distilled, well, spring) and some
black or green tea. Some people use herbal teas, but many of them will not work, especially if they're oily. Earl Grey is unacceptable because it's flavored with orange peel oil (while oddly, Orange Pekoe is straight tea). It's also better to get organic tea, and much cheaper to buy it in bulk than in bags. I suggest going to the nearest natural food store and picking one based on smell. I like to use a blend of English or Irish Breakfast, Jasmine green, and a bit of Lapsang Souchong. Pu-erh is said to be excellent. Also, for some reason, they say not to use decaf.
Then you need some kind of
strainer to get the tea leaves out, and finally you need some kind of
sugar. Most people use plain white sugar, which is dirt cheap because of subsidies. There is no health benefit to organic white sugar, since the refining process takes out all toxins except the sugar itself -- which supposedly is rendered non-toxic by the fermentation. I've read different things about using less refined sugar cane products, like turbinado/demerara. Agave and maple should be fine. Honey has anti-microbial properties that will damage or kill the culture.
You might also try
fruit juice kombucha. It's not clear yet if fruit juice can totally replace tea and sugar or just supplement it. If you experiment, be sure to keep a spare SCOBY and liquid in reserve, in case your original goes bad!
Procedure
The basic idea is to make a giant batch of tea with sugar, let it cool, add a SCOBY and some starter Kombucha, and stick it somewhere for a week. Recipes vary, but I follow one that says for 3-4 quarts of water, you need 15 grams loose tea (5-7 bags) and a cup of sugar. I got a good scale and found out that 15 grams of tea is almost exactly a quarter of a cup.
Instead of measuring the water with cups, I measure with the containers I'm using. In a gallon jar, you want the surface of the liquid to be just where the jar starts to narrow, because the new SCOBY will form on the surface, and if it uses the jar's full width it has more interface and faster fermentation. So you could measure your water with the jar, but reduce it a bit because you need room at the end to add the SCOBY and the starter liquid.
Luckily, the pot I use is just big enough to hold enough water to combine with the extra liquid to get to the right level in the jar, so I fill the pot to the brim and start it heating. In any case, you need to know roughly how much water you're using, so that you can add the right amounts of sugar and tea leaves.
When the water boils, I take the pot off the heat, put the tea leaves in, steep it for 15 minutes, then pour it through a gold tone coffee filter into the big jar, and then add the sugar.
Once you have hot sweet tea, give it a few hours to cool to below body temperature, and then add the SCOBY, plus at least a cup of Kombucha from the last batch. If you have only liquid and no SCOBY, a new SCOBY will still form on top, but it will take much longer. If you have only a SCOBY and no liquid, it will also take longer, and you should add a quarter cup of white vinegar, which will make enough acidity to help the fermentation and prevent other organisms from taking over.
Everyone says not to use apple cider vinegar, only distilled white. You can also use it for cleaning the SCOBY, and cleaning the jar and pot before you use them. Do not clean the SCOBY with chlorinated water, and also it should not touch metal.
When the tea has cooled and the critters are added, cover it with a clean piece of cloth, secure that with a rubber band, and put it in a dark place between 70 and 85 degrees F (20-30C). This will be difficult in the cooler seasons, because it's insane to heat your whole house to 75 just for Kombucha. Try to find a warm microclimate somewhere. In the worst case, fermentation will just take a really long time, maybe more than a month. Or if it's really warm, it could be done in five days.
As the Kombucha culture eats the sugar, it will make a film on the surface of the liquid, which will thicken and turn into a new SCOBY. Generally the new one will be stuck to the old one, and you can either pull them apart or keep them both in there for the next batch. Eventually the older ones will get ugly and you'll want to throw them out. They should be great for compost, but not good for human consumption! I've heard chickens like to eat them. You can store them frozen for a while, so it's a good idea to freeze one as a backup, and periodically replace the frozen one with a fresher one.
The finished drink should be slightly fizzy and sweet-sour. If it's really sour it's gone too far, and if it still tastes like sugared tea it hasn't gone far enough. Color will vary. When I have a finished batch, I pull out the SCOBY and pour most of the liquid into a three quart glass jug. (Three quart jugs stealthily replaced gallon jugs around 2008.) This leaves more than enough liquid in the big jar for the next batch. If you don't want to start right away, you can leave the SCOBY and the spare liquid in the big jar for weeks. Another method is to brew it continuously -- just keep the SCOBY in the big jar, and every time you take some Kombucha out, replace it with the same quantity of sweetened tea. This saves work in pouring and cleaning, but adds much more work in tea brewing. Also, you lose the opportunity to get more fizz, which builds up if you put the finished drink in sealed containers at room temperature.
It sometimes happens that the culture gets moldy. Do not worry about slimy stringy brown stuff -- that's normal. It's also normal for a new SCOBY to begin as tiny white patches on the surface of the liquid. And little black spots in the SCOBY are probably bits of tea that got through the strainer. Mold will be fuzzy and green. If you see or taste mold, you have to dump it all and start over. If it's your first time making Kombucha, you might want to drink some made by somebody else, or made commercially, so you know what it's supposed to taste like. Other than tasting like vinegar if it goes too far, it should not taste bad. And if it goes too far, you can use it as vinegar!
I've read all kinds of things about how much you should drink -- or how much you can get away with -- from two ounces a day up to a gallon. Definitely you should start small, in case your body doesn't like it, and if it does, you can work up to a pint a day or more. If you've ever bought Kombucha at the store, the most shocking thing is how much they mark it up! I estimate the cost of making it at home, with organic fair trade bulk tea, at about 30 cents a quart.
(public domain, anti-copyright, last updated November 2011)