For some time, now, I've been making kombucha at home. I've seen many other sets of instructions, but they all seem to be making it far more difficult that it needs to be.
So, here is how I do it.
The tools I use:
• 1/2 gallon mason jars. These are sold in sets of six. Each will make three 16-ounce bottles. I bought these at a local home store, but you can find them nearly anywhere.
• 16-ounce pop-top bottles. I bought a dozen of these at a local home-brewery supply.
• A wide-mouthed mason jar funnel.
• A narrow-mouthed funnel that will fit into the mouths of the pop-top bottles.
• 1/2-cup dry goods measuring cup
• 2-cup wet goods measuring cup (though I'm only measuring 1-cup, so you could use a smaller)
• A narrow-mesh strainer I bought at Cultures for Health
• Water. You want water that's not chlorinated or flouridated, which means you don't want tap water. Bottled spring water will work, if you're sure it isn't chlorinated or flouridated. Well water, if you're sure it doesn't have microorganisms that might compete with the scoby. If you have doubts, you can always use distilled.
• Tea. I buy boxes of black tea bags at Whole Foods. Black tea will work, so will green tea. You don't want flavored teas.
• Sugar. You want organic. Pesticides will interfere with the scoby just like chlorine or florine will.
• Coffee filters. I use one on each jar, during the ferment.
Step 1: Steeping the Tea
Most people seem to steep their tea in hot water. This is entirely unnecessary.
Tea steeps just fine in cold water, it just takes longer. The problem is that steeping tea at room temperature takes long enough to be dangerous - you can start to get mold to form, and that's the one thing you don't want.
So, steep it in the refrigerator. That takes even longer, but the cold will keep mold from growing.
I fill a jar with 6-1/2 cups of water (halfway between the 6 and 7 cup lines on the jar), add four tea bags, screw on the top and set it in the fridge for two or three days.
Step 2: Starting the Ferment
When the tea has steeped, take the jar from the fridge, and take your oldest jar of fermenting kombucha from where ever you're keeping them.
Wash your hands, remove the cap from the steeped tea and take out the tea bags.
Pour 1/2 cup of sugar into the jar. I never bother stirring it. It's going to sit on the shelf for weeks, it'll dissolve in its own time.
Next, you'll want to take half the scoby from your fermenting kombucha, and 1 cup of kombucha, and add them to your steeped tea-and-sugar mix. This will come close to filling the jar.
Cover the mouth of the jar with a coffee filter, secure it with a rubber band, and put the jar someplace relatively warm and dark. I save one shelf in a kitchen cupboard for the jars.
You'll want to ferment the tea for at least two weeks before you bottle it. Three is better. Four is fine. The longer you let it go, the less sugar and the more vinegar.
In your early batches, you'll want to double things up, each time, starting two new jars for each old jar you tap. For my very first batch, I started two jars of tea, with half of a 16-ounce bottle of commercial (unflavored, raw) kombucha in each. The scoby itself isn't necessary, there's enough yeast and bacteria in a live culture kombucha to kick-start the process.
What is important is the acidity. All that sugar will quickly grow mold, at room temperature, if you haven't brought the acidity up. If you're using a borrowed scoby, as is the tradition, add a cup of cider vinegar to get the acidity to where you need it to be. Or a cup of kombucha works just fine.
When you have enough jars brewing to meet your usage, you'll stop doubling up, and settle into a steady state.
Each 1/2-gallon jar produces three 16-ounce bottles. I go through one bottle a day, most days, so I set a new jar to ferment every three days.With six jars working, that means my kombucha is fermenting in the jar for 18+ days.
Step 3: Bottling
After you've finished prepping your new jar for fermentation, you'll have the old jar, just having finished its fermentation, ready to bottle.
This is simple enough. Just stick a funnel into the mouth of a bottle, and pour it in. I use a strainer I bought at Cultures for Health, but that's not strictly necessary. There's nothing in the kombucha except for kombucha and filaments of scoby, and even if you do strain it, you'll have new filaments forming in a couple of days.
You'll want to fill the bottles almost to the top. The kombucha isn't going to stop fermenting just because you've moved it to a different bottle. It'll have used up most of its sugar, so it won't generate much more CO2, but it will generate some. And the more room you leave at the top of the bottle, the more pressure will build up.
You can drink the kombucha immediately, or you can let it sit for up to a week. The longer, the more carbonation.
Some people add more sugar, to increase sweetness and carbonation. Some add flavorings. Ginger root is a favorite.
Experiment and see what you like