Juice oranges, grapefruit, lemons, and limes and strain pulp.
Line up 4 (25 ounce) bottles with flip top lids or other air tight bottles.
Pour 2 tablespoons orange juice, 2 tablespoons grapefruit juice, 2 tablespoons lemon juice, 2 tablespoons lime juice, and ¼ cup maple syrup into each 25 ounce bottle.
Using a funnel, pour freshly made homemade kombucha into each 25 ounce bottle leaving 1-2" head space.
Let bottles sit out (at 75° - 85°) 3-5 days, making sure to pop the lids each day to let out the pressure of the carbon dioxide. Taste each day to test its flavor and fizziness.
Notes
Use freshly made kombucha that has not been refrigerated yet.