Before beginning, clean all equipments and utensils with a paper towel moistened with white vinegar.
In a large pot, boil 1 gallon of water.
After it starts boiling, dunk the tea bags in the water and remove the pot from heat.
Pour sugar into the tea and stir with a clean wooden spoon until the sugar dissolves.
Let the sweetened tea sit for several hours until it reaches room temperature. Sometimes I do this process at night so it cools overnight.
Once the tea is cooled, take out and discard the tea bags and pour the tea into a gallon glass jar.
Drop the SCOBY into the jar on top of the tea and pour 1 cup of white vinegar on top.
Cover the top with a cloth and close it with a rubber band.
Leave in a dark place at room temperature and out of sunlight for 6-10 days. The warmer the temperature, the shorter the fermentation time.
On the 6th or 7th day, taste the kombucha. It's ready when it tastes sour and not too sugary.
Now is the time to flavor the kombucha, if you like. Take out the SCOBY (there should be 2: the mother and the baby). Add 1 cup of fruit juice and stir.
Pour out the kombucha into airtight bottles. Fill them up almost all the way to the top.
Close the lid tightly and and keep them again in a dark place at room temperature for 3-5 days.
On the 3rd day, you can open up a bottle to see the carbonation level.
Once fully carbonated to your liking, store in the refrigerator so it slows down the fermentation process.