5. Once it has fermented, I distribute all but 2-3 cups of the kombucha into smaller bottles and flavor it. This step is called second fermentation, which gives the drink its effervescence (fizziness). Pour the kombucha into jars with tight-fitting lids (growlers or old store-bought kombucha bottles work fine, lately I’ve been using leftover Gerolsteiner bottles which are very easy to store). Fill the bottles only 3/4 of the way with kombucha. Fill the rest of the bottle up with fruit juice or chopped dried/fresh fruit. Throw in some fresh peeled ginger if you’re up for it (about 1/2″ per liter). If using a juice that isn’t very sweet (like cherry or cranberry), add in a little honey or sugar, about 1 tsp per liter. Fill up the jar until it’s nearly full – the less air you leave inside the bottle, the more fizzy it will get.