In a sauce pot, bring 2 cups of the water to a boil, then take the water off the heat. Add the black tea and allow it to steep for 5 to 10 minutes.

Strain out the loose tea or remove the tea sachets/bags, then stir in the sugar until completely dissolves.

Pour the strong sweet tea into a clean gallon jar, then fill the jar with the 12 cups of water.

Use a thermometer to make sure that the temperature of the tea is between 75°F (24°C) and 85°F (29°C). Any higher or lower could potentially kill the SCOBY.

Once the tea is at the correct temperature, pour in 2 cups of the SCOBY. Stir the mixture, then use a pH strip to ensure that the pH level is between 2.5 and 3.5. Any lower or higher, and the kombucha could be unsafe to drink.

Carefully add the pellicle to the jar. It is normal for it to float or sink.

Cover the jar with a clean cloth or jar cover and secure it with a rubber band or twine. This will allow the kombucha to breathe while also keeping out bugs, dust, and other particles. Place the jar in a safe place away from sunlight.

Allow the kombucha to ferment at room temperature for 7 to 14 days. The longer the kombucha ferments, the more acidic it will become. Taste it after 7 days to see if the flavor suits your taste. Allow it to keep fermenting if you prefer a tangier bite.

Once the kombucha is to your taste, remove the pellicle and reserve 2 cups of the kombucha. Keep them in a separate jar covered with a cloth and rubber band for future use in your next batch.

Bottle the remaining kombucha into glass swing-top bottles. and allow it to ferment for an additional 3 to 4 days for a carbonated beverage.

Store the bottled kombucha in the refrigerator for up to 3 months. Gently swirl the bottle to mix the sediment at the bottom before drinking.