16 cups water – divided between SCOBY starter and main brew
1.125 cups granulated sugar – divided between SCOBY starter and main brew
10 bags black tea bags
2 cups unflavored raw kombucha
0.5 cups fruit juice (100%) – optional for second fermentation
Instructions
Wash a 1-gallon glass jar, a 1-quart jar, a large nonreactive pot, a ladle, and 6–8 swing-top bottles with hot soapy water; rinse well and air-dry. Avoid prolonged contact with reactive metals once the tea is acidic.
Brew the sweet teas: Bring all the water to a boil, then turn off the heat. Stir in all the granulated sugar until dissolved, add all the black tea bags, and steep 10 minutes. Remove and discard the tea bags. Cool the sweet tea to room temperature (68–85°F), then divide: measure 2 cups for the SCOBY starter and reserve the remaining sweet tea for the main brew.
Grow the SCOBY: Pour the 2 cups cooled sweet tea into the 1-quart jar and add the unflavored raw kombucha. Cover the jar with a clean, tightly woven cloth or paper towel secured with a rubber band. Ferment undisturbed at room temperature, out of direct sunlight, until a smooth, opaque layer (SCOBY) 0.25–0.5 inch thick forms on the surface and the liquid smells pleasantly tart, 7–21 days.
Start the main ferment: Pour the remaining cooled sweet tea into the 1-gallon jar. With clean hands, gently lift the SCOBY from the starter jar and place it on the surface of the sweet tea. Add 2 cups of the acidic starter tea from the SCOBY jar to the gallon jar. Cover with cloth and secure. Ferment at 70–78°F out of direct sunlight until the kombucha tastes slightly tangy with a hint of sweetness, 7–10 days; a new thin SCOBY will form on top.
Bottle and optionally carbonate: With clean hands, remove the SCOBY and 2 cups starter tea to a clean jar for your next batch. For plain kombucha, ladle the remaining kombucha into bottles using a funnel, leaving 1 inch headspace, seal, and refrigerate. For a second fermentation, add 1–2 tablespoons fruit juice to each 16-ounce bottle, fill with kombucha leaving 1 inch headspace, seal, and ferment at room temperature 2–4 days until lightly fizzy, burping daily to release pressure, then refrigerate.
Serve and store: Chill well before opening. Open over a sink, pour gently, and leave sediment behind if you prefer a clearer drink. Keep refrigerated up to 4 weeks and always reserve starter tea for future batches.