Make the tea base: Bring the water to a boil. Remove from heat and stir in the sugar to dissolve. Drop in the tea and allow it to steep until the water has cooled. Depending on the size of your pot, this will take a few hours. You can speed up the cooling process by placing the pot in an ice bath.
Add the starter tea: Once the tea is cool, remove the tea bags or strain out the loose tea. Stir in the starter tea. (The starter tea makes the liquid acidic, which prevents unfriendly bacteria from taking up residence in the first few days of fermentation.)
Transfer to jars and add the scoby: Pour the mixture into a 1-gallon glass jar (or divide between two 2-quart jars, in which case you'll need 2 scobys) and gently slide the scoby into the jar with clean hands. Cover the mouth of the jar with a few layers tightly-woven cloth, coffee filters, or paper towels secured with a rubber band. (If you develop problems with gnats or fruit flies, use a tightly woven cloth or paper towels, which will do a better job keeping the insects out of your brew.)
Ferment for 7 to 10 days: Keep the jar at room temperature, out of direct sunlight, and where it won't get jostled, checking the kombucha and the scoby periodically.
It's not unusual for the scoby to float at the top, bottom, or even sideways during fermentation. A new cream-coloured layer of scoby should start forming on the surface of the kombucha within a few days. It usually attaches to the old scoby, but it's ok if they separate. You may also see brown stringy bits floating beneath the scoby, sediment collecting at the bottom, and bubbles collecting around the scoby. This is all normal and signs of healthy fermentation.
After 7 days, begin tasting the kombucha daily by pouring a little out of the jar and into a cup. When it reaches a balance of sweetness and tartness that is pleasant to you, the kombucha is ready to bottle.
Remove the scoby: Before proceeding, prepare and cool another pot of strong tea for your next batch of kombucha, as outlined above. With clean hands, gently lift the scoby out of the kombucha and set it on a clean plate. As you do, check it over and remove the bottom layer if the scoby is getting very thick.
Bottle the finished kombucha: Measure out your starter tea from this batch of kombucha and set it aside for the next batch. Pour the fermented kombucha (straining, if desired) into bottles using the small funnel, along with any juice, herbs, or fruit you may want to use as flavouring. Leave about a half inch of head room in each bottle. (Alternatively, infuse the kombucha with flavourings for a day or two in another covered jar, strain, and then bottle.
Carbonate and refrigerate the finished kombucha: Store the bottled kombucha at room temperature out of direct sunlight and allow 1 to 3 days for the kombucha to carbonate. Until you get a feel for how quickly your kombucha carbonates, it's helpful to keep it in plastic bottles; the kombucha is carbonated when the bottles feel rock solid. Refrigerate to stop fermentation and carbonation, and then consume your kombucha within a month.