Place hydrated water kefir grains in a 24-ounce glass mason jar or other sterilized glass fermentation vessel. Pour coconut water on top. There should be an inch of headspace. Cover jar tightly with a regular or airlock lid. Allow mixture to ferment in a cool, dark place for up to 24 hours or until carbonation forms.

Strain the coconut water to remove the kefir grains, and return coconut-kefir water back to the original jar or glass vessel. Once grains are removed, they may be stored in sugar water in the refrigerator. You now have fermented coconut water kefir.

For the second fermentation, simply add the fresh berries to the coconut water kefir. The berries will create a good amount of carbonation, so release the gas often, especially if you’re not using an airlock lid. (TIP: It is very important to release gas during the second fermentation.) Allow liquid with berries to ferment in a cool, dark place for at least 6 hours and up to 12 hours, but no more. When the coconut water kefir is quite effervescent and the berries have a bubbly mouthfeel, the second fermentation is complete. Open the bottle over the sink and enjoy right away, or refrigerate to slow the fermentation process and enjoy later. May store up to 2 weeks refrigerated. Best served chilled.