Empty half of the juice into a mason jar and save for a second batch.

Pour filtered water into the plastic store bought juice until the bottle is 3/4 full

Add a pinch of champagne yeast.

Close bottle and give a quick shake.

Open bottle and carefully squeeze as much air as you can out of bottle.

Quickly cap the lid.

Let sit at room temperature.

When you see the liquid level lower (i.e. more air in the bottle), repeat the squeezing technique.

Continue to do this until the bottle puffs out and is very hard. (usually 24-48 hours).

Transfer to the refrigerator and enjoy!