01 - Bring 2 quarts of filtered water to a boil. Add tea bags or loose-leaf tea and steep for 10 minutes, then remove tea bags or strain leaves.
02 - While tea is hot, dissolve 1 cup granulated sugar, stirring thoroughly. Allow the sweetened tea to cool to room temperature; this step is critical to protect the SCOBY or culture.
03 - Transfer cooled sweet tea into a sanitized large glass jar. Add the SCOBY and starter liquid, or unflavored store-bought kombucha as indicated.
04 - Cover the jar loosely with a clean cloth or paper towel and secure it with a rubber band. Let ferment at room temperature, away from sunlight, for 5 to 7 days.
05 - After 5 days, begin tasting daily until the beverage is mildly tart and slightly effervescent, stopping before it becomes overly sour.
06 - Remove the SCOBY and reserve about 3/4 cup of kombucha for starting future batches. Add selected fruits, herbs, or spices for flavor.
07 - Pour the flavored kombucha into clean bottles, leaving 1 inch headspace. Seal tightly and let ferment at room temperature for 1 to 3 more days to develop natural carbonation.
08 - Transfer bottles to the refrigerator once carbonation is achieved. Strain out solid flavorings before pouring. Serve cold.