If using frozen blueberries, allow to thaw first so that it's easy to smush them into bottles.
Line up 4 (25 ounce) bottles with flip top lids or other air tight bottles.
Smush ½ cup blueberries 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.
Refrigerate when you are happy with the amount of fizz and flavor.
Notes
Use only homemade kombucha that hasn't been refrigerated yet.If you want a really sweet kombucha, you can add maple syrup, agave syrup, or simple syrup.