Fill your gallon jug with water and then pour that into your pot. (This is an easy way to measure the volume you need.)
Bring water to a boil and remove from heat. Add sugar and tea. Stir and allow to steep with the lid off. You want your water to cool to room temperature.
Once water has cooled to where you can stick your finger in and it’s neither too hot nor too cold, transfer it to your clean gallon jar. Stir in the ½ cup of kombucha. Use a wooden spoon to add your SCOBY.
Cover with cheesecloth and secure with a rubber band. Keep in a slightly warm spot, like beside your oven or on top of your fridge. By the window in the winter would be a bad idea as the cooler the area, the longer it will take to ferment.
Be patient. Let sit for 2-4 weeks. Start tasting it after two weeks and then every few days until it’s to your desired taste.
If you don’t have a ½ cup of kombucha, it’s okay. This simply acts as a starter. It just might mean your kombucha will take a little longer to ferment.