We have been making kombucha tea for a while now and are really enjoying it. KT is a fermented drink filled with good stuff for your gut :) mainly - probiotics. It also has good things for your body, but that can vary from brew to brew.
A friend of mine gave me one of her scobys (symbiotic colony of bacteria and yeast) a few months ago, and we already have a new jug going. The original scoby you start with is often called the 'mother'. Some call it a 'mushroom' [though it is not a mushroom]; it's a solid mass of yeast and bacteria that produces more solid masses of yeast and bacteria. Eventually there will be a baby scoby on top of the mother that you can peal off and start another jug with. Scobys kind of look like funky pancakes.
To make KT, first you need a scoby and 1-2 cups of starter tea (finished tea from the last batch or raw KT purchased at a health food store). You can get a scoby and starter tea from a friend or online (ebay is a good place to start). If you get it online, be sure you know what you are getting ... some will sell 2 scobys at once that are 6" in diameter (this will be enough for two 1-gallon jugs). Others will sell one scoby that is only 2"-3" and will only make 1-2 quarts of KT. So, do your research.
Here is a picture of my big scoby in the starter tea (2 cups from the last batch) - the white you see on top is the baby scoby; it's hard to see the mother scoby in this picture. The tea to the left is what came from the last batch minus a little we drank - notice the bubbles ... it looks like beer or soda when you are pouring it into the jars. The tea to the right is what was left of the batch before. The tea in the 2 1/2qt jug in the back is a batch that is not done yet - that was made with a baby scoby and seems to be taking a little longer.
Next you need tea sweetened with white sugar (yes, finally a use for white sugar!). You can use other sweeteners, however white sugar breaks down the easiest and quickest. Don't worry about blood sugar levels - the bacteria actually feed on the sugar so most of it is used up by the time you consume the KT.
Bring about 6c of filtered or distilled water to a boil. Turn it off and add 6 tea bags (black or green or a mix of both; I prefer green but will use black from time to time). Cover and let it sit for ~15 minutes. Add 1c white sugar, mix well.
Cover the pot with a towel so flies or other bugs do not get in. Allow to come to room temperature before adding it to the scoby and starter tea - adding it when it is hot will KILL it. To hasten cooling, you can set it in a sink of cold water.
Carefully pour into the waiting jug, add more filtered or distilled water to 1"-2" to the top and cover with a coffee filter secured by a rubber band. Be sure it's on good so fruit flies do not invade your brew.
Notice the scoby here is a little crooked - it might even be at the bottom of the jug for a time. Eventually it always seems to level out and lay flat at the top.
Now let it sit there for 5 days or longer; it will brew faster in hotter weather and slower in cold weather. Also, it will brew quicker with white sugar, longer with other sweeteners (or so I've read ... I've never tried anything but white sugar (now I use organic cane sugar)). I don't really know how to tell you when it's done ... it tastes kind of like very mildly sweet sparkling apple cider. It should not be sweet, yet it should not be sour either. It will be slightly effervescent at this point; you will see bubble at the top and hear it fizz some when you stir it. Pour all but ~1 1/2c into glass jars with plastic lids (not metal). If you must use metal, add a layer of plastic wrap between the brew and the lid. Leave the jars sit out on the counter; 'burp' them once a day to ensure the jars do not explode due to further fermentation. (if you are using grolsch-style bottle lids burping is not necessary) Little scobys will form in each jar if it sits long enough. You can save these and use them, or just drink them ... or give them to the chickens.
The finished kombucha will be fizzy like soda. It is wise to open over a bowl in case it spills out.
It's recommended that you start with a half cup a day (4oz) and work your way up. Some drink a quart a day. I don't have a lot and there is a lot of us here, so I only drink about a cup a day. Eventually I hope to drink a lot more daily.
You can add a tablespoon or so of frozen juice concentrate to each quart jar for flavor. Or you can try adding some frozen berries to each jar or a chunk of ginger. We mostly just drink ours 'plain'.
Update 5-19-15: we like to flavor ours ... here is a video demonstration:
FLAVORED KOMBUCHA
An alternative method of brewing is called the 'continuous brewing method'. Here is information on how to do that; this link also has other information about kombucha tea.
CONTINUOUS BREWING METHOD FOR KOMBUCHA TEA This is on the Weston A. Price website ... I cannot endorse everything he or his students teach, however I do appreciate and agree with their thoughts/teaching on fermentation and soaking grains.
I had to edit this and add this great website for trouble-shooting kombucha brews.
"Kombucha, The Balancing Act" There is a balance between the yeast content and the bacteria content; too much of one or the other will have an effect on various things in your KT. This is an excellent resource!