Bring 4 cups of water in a medium pot to a boil. Remove from heat.
Add 1 cup of sugar to a heat-proof container and pour in about 2 cups of the hot water. Stir until the sugar dissolves.
Add tea bags to remaining hot water. Let cool.
Once the tea and sugar water have cooled to room temperature (do not add until cooled!), pour the tea and sugar mixture into the gallon jar with the SCOBY and reserved kombucha. Add enough water to fill the jar (about 6-8 cups). Stir well.
Make sure the jar is dry and cover with a few coffee filters or cheese cloth. Secure tightly using rubber bands.
Move to a cool, dry area to ferment for at least 1 week and up to 6 weeks.
To bottle:
When you think you're ready to bottle, remove the cover and test the kombucha using a straw. Dip a clean straw into the kombucha and cover the top of the straw with you finger. Transfer into a cup to taste. If it is to your desired taste, you're ready.
Carefully remove the SCOBY to a bowl. Set aside for your next batch, along with 2 cups of unflavored kombucha.
Pour the kombucha into a glass or plastic pitcher.
*You can transfer this to the refrigerator now or bottle*
To bottle, place your bottles close on the counter. Using a funnel, carefully pour in the kombucha. At this point, you can flavor your kombucha if desired.
Carefully close the bottle and transfer to the counter to ferment a few more days for extra bubbly kombucha or transfer to the refrigerator immediately.
Using the reserved SCOBY and kombucha, make another batch (using instructions above).
When ready to drink, carefully pop the lid making sure it's away from your face and pour. Enjoy!
Notes
*Make sure to use clean utensils and that your work area is clean. *You'll use about 14 cups of water total. *Use real sugar. Do not use artificial sweeteners, honey, or maple syrup. *Do not use flavored or caffeine-free tea. Black or green tea works best. *Make sure to completely cool the tea and sugar-water because heat can harm your SCOBY. *Wash your hands before handling the SCOBY and after transferring it. *Use glass or plastic utensils. Using metal can cause harm to your SCOBY. Glass is preferred, but plastic is ok as long as it is not keeping for extended periods of time. *Fermentation time is 1 to 6 weeks. The longer you ferment the more acidic-tasting your kombucha will be because the sugar will be more broken down & it won't be as sweet. *You can transfer the pitcher of brewed kombucha to the refrigerator or bottle it. Bottling is helpful because you can take your kombucha to go. The pitcher is convenient because all you have to do is pour your kombucha into a cup. It's up to you to decide. I prefer bottling, especially when I am flavoring the kombucha. *The second ferment is optional but will give you extra bubbly kombucha. It is common to have a second ferment when flavoring your kombucha. Ferment at room temperature for only 1 to 2 days then transfer to the refrigerator. *The refrigerator stops fermentation. *Each batch makes one gallon (16 cups) but you will save about 2 cups of kombucha for the next batch, leaving you with about 14 cups of kombucha to enjoy.