Bring 2 cups filtered water to a boil.
Add tea bags (or 1 large tea bag) and remove from heat. Allow to steep 5-10 minutes.
Add sugar and stir to dissolve. If the sugar is taking too long to dissolve, turn on the heat again and heat 1-2 minutes to dissolve the sugar.
Add sweetened tea to a clean gallon sized jar. Fill with room temperature filtered water. Using a kitchen thermometer, make sure the tea is 75°-85°. (By adding room temperature water to the hot tea mixture it will be around 85°-87°, but it will cool down to room temperature.)
Add the starter tea culture and starter tea (1-2 cups) to the sweetened tea. Secure a tea towel or coffee filter over the jar with a sturdy rubber band.
Place the jar in a warm area that is between 75°-85°. Cold temperatures cause mold, so a warm area is necessary for the success of your kombucha!
The kombucha will be ready between 7-21 days. Taste it at day 7. If it's too sweet, ferment it longer. I like to brew mine for 18 days. Save 1-2 cups for the next batch and start another batch!