To make kombucha from a culture, bring 1 gallon of water to a boil, turn the heat off, and add 12 tea bags. Allow the tea bags to steep for 4 minutes, stir in 1 cup of sugar, and allow the tea to cool until it is room temperature. Then, pour the tea into a glass brewing container, and add the liquid and powder kombucha cultures. Allow the kombucha to brew at room temperature for up to 30 days.
Cover the mouth of the container with a dishcloth or piece of cotton to keep pollutants out of the tea. Begin tasting the tea after it brews for seven days. Move the tea into the refrigerator after it reaches the desired taste. Don't use stevia or sugar alternatives to make kombucha, as sugar alternatives don't usually work as well as granulated sugar.
To reuse the culture indefinitely, remove the scoby, or the culture that grows in prepared kombucha, and store it in a covered glass container of kombucha or sweet tea. Keep the scoby at room temperature. When making a new batch of kombucha, follow the same procedure, but add the scoby and at least 1/2 cup of prepared kombucha to the tea in place of the starter.