Homebrewers, take note.
It is VERY important to fill bottles of kombucha correctly.
The perfect fill level is illustrated in the photo above, marked by the purple notes that look like the number 7. I instruct homebrewers to use recycled Grolsch bottles.
Another tip: right below the lip ????
Fill your bottles nearly to the top, into the neck of any bottle. Ensure there’s no more than an inch of headspace.
Why does it matter?
Trust me on this, the level you fill your bottle matters. When given too much space, your brew will produce excessive levels of carbonation. If not given enough, the kombucha may turn out flat.
Early in my brewing days, I was finishing a flavoring process. I didn’t have enough brew to fill one of my bottles all the way – only about half-full.
So, I continued my process and left the half-full bottle with my others for the full cycle. I remember the flavor was my FAVORITE: raspberry ginger.
When it was ready, I excitedly grabbed the half-bottle from my fridge first. I opened it over my sink, like any other. It was a good thing I wasn’t looking down because as soon as I started to flip the hinge, the top BLEW off with the force of a heavy-duty pressure washer. Like, one I’d have to rent! ????
There’s still raspberry on my ceiling if you don’t believe me. The biggest thing, though: if I would have been looking at the bottle directly when I opened it, I know it would have injured my eye. Bless my husband for our conversation ????
If I have the guts to re-create this scenario in the future, I’ll post a video.
Tl;dr If you don’t fill your bottles correctly, you risk potentially harmful explosions.
Here’s a poor fill-level example, from free stock footage if you’d believe it! There is way too much room in these bottles.