From Brew & Buch

INGREDIENTS
½ gallon kombucha from a first fermentation (this is not store bought kombucha, 1.9 L)
4 tsp elderflower syrup (20 mL)
8 fresh mint leaves (optional)

INSTRUCTIONS
Bottle: Evenly distribute elderflower syrup into bottles. Pour in first fermentation kombucha, leaving 1 to 2 inches free at the top. Optionally add mint to each bottle.
Ferment: Place in a dark, room temperature area for 3 to 10 days, until it reaches the carbonation level you like. This process will go faster in warmer climates, and slower in cooler climates.
Enjoy: Chill in the fridge before serving, optionally straining before serving. Can be stored in the fridge, tightly sealed, for several weeks.