How to ferment your own Kombucha
What is Kombucha?
Kombucha is a lightly sparkling fermented tea drink, usually flavored with fruits or herbs, that likely originated in ancient China. It’s a little sweet, a little sour, and naturally packed full of active cultures to strengthen your gut microbiome.
Kombucha is made by adding strong sweet tea to a starter, or a SCOBY – that’s a symbiotic culture of bacteria and yeast. The SCOBY works together to turn the tea into ‘buch: the yeast eats away at the sugars in the tea to create carbonation, while the healthy bacteria give us the acidic, tangy flavour we love from our fermented foods! The SCOBY also produces a pellicle, a cellulose film that develops on the top of the fermenting tea. This helps protect the liquid from invading cultures that could cause mould, and can either be left in the starter, composted, or turned into a tasty SCOBY snack when your first fermentation phase is done!
Your kombucha can be enjoyed directly after this first fermentation phase, or it can be further flavoured with just about anything (edible) you can imagine! Adding fruit, juice, or extra sugar during a secondary fermentation phase will give the yeast enough sugar to produce CO2, resulting in a naturally fizzy and refreshing drink!
Where to Start
The first thing you will need to brew your own kombucha is a SCOBY. Check around with local markets, friends, and Facebook groups and you will likely find someone happy to give you some of their starter! If you can’t find one that way, don’t worry. Any bottle of unpasteurized, unflavoured, raw kombucha should have enough active cultures to get you started!
A glass brewing vessel such as a large mason jar for the first fermentation (roughly 5L is a good place to start)
A cloth or breathable cover for the brewing vessel (tea towels or old t-shirts work great, but avoid cheesecloths because they are too porous)
A set of fermentation-grade bottles for secondary fermentation and flavoring (commercial kombucha bottles or flip-top bottles – you can use cleaned-out Grolsch flip-top beer bottles, or buy from a home brew store or website)*
An extra glass brewing vessel for creating a SCOBY hotel**
*It is very important to get fermentation-grade bottles made for carbonation! Do not use bottles labelled “decorative,” as they are not designed to withstand pressure from carbonation.
Some notes on your equipment:
Try to avoid contamination as much as possible by thoroughly cleaning your equipment. Hot water and dish soap is perfectly fine, and occasionally it is good to sterilize with white vinegar or alcohol. Also avoid double dipping when tasting and make sure to wash your hands thoroughly!
Avoid metal coming in contact with your brew. Metal may react poorly with the SCOBY and can compromise the integrity of your culture. Use glass, silicone, wood, or hard plastic materials instead.
Water (in my experience, tap works just fine)
Sugar (plain white is best)
3 bags (~8g)
3 bags (~1TBSP)
Kombucha starter (if starting from store-bought raw kombucha, use that instead!)
*If this is your first batch from a commercial kombucha, double the starter amount
How to Brew
- Brew your sweet tea. Make a concentrated sweet tea by adding your tea bags and sugar to boiling water, and letting steep for ~10 minutes. The sugar will dissolve, and the tea should be a bit darker than what you might normally drink.
- Let it cool. If you do not let your tea fully come to room temperature, you risk killing your SCOBY when you add it. So make sure it’s cooled off!
- Add your starter. You can also use the kombucha left in the vessel from a previous batch as your starter for continuous brewing.
- Cover it up. Cover your brewing vessel with a breathable cloth, using a rubber band to hold it tightly in place. The SCOBY needs access to oxygen to convert the tea into ‘buch, but the cover will keep out any little bugs or stray dust that might contaminate the batch.
- Let it sit in a warm area of the house, out of direct sunlight. The ideal temperature for brewing is between 20°-27°C (68°-80°F). If it is a new batch, it will develop a cellulose pellicle on top to indicate its progress. Begin tasting your ‘buch after about a week. If it is still too sweet, leave it a bit longer; it will become more acidic the longer it ferments, and it is entirely up to your preference when it is ready!
- Bottle the ‘buch. When your first fermentation is done (however you like it), add some fruit/juice/herbs or other flavorings to your bottles, and fill them not quite to the top with your kombucha. When adding fruit juice, fill the bottle 10-20% of the way with your juice before adding kombucha. If adding fruit pieces (frozen works too!) or herbs, experiment a bit with how much to add for your preferred flavor (and make sure to chop small enough to get it back out of the bottles!). If you prefer ‘buch without added flavors, add ~4g (1 teaspoon) of sugar to your bottles to promote carbonation during the secondary fermentation. Reserve some of your kombucha in your brewing vessel to be the starter for the next batch!
- Let it sit again. Let your bottled ‘buch sit at room temperature for anywhere between 1-7 days. The longer it sits, the more fizzy (and acidic) it will become. If you are unsure if it is ready, pop open one bottle just slightly to test. How bubbly you like your ‘buch is up to you!
- Refrigerate it. Cooling down the bottles will slow or stop the fermentation process and allow the CO2 to settle before opening.
- Enjoy your ‘buch!
I like to keep a second brewing vessel with a SCOBY hotel, or a batch of starter liquid separate from my main brew that I can always use in case my main batch goes wrong!
Jam works great for an easy flavoring. No chopping and you can get all different varieties. You can also use simple syrups, flowers, herbs – almost anything! Experiment to find your favorites, or get some more ideas here. You can strain out the bits of fruit using a mesh strainer as you pour if you prefer.
What to Look For
After a few days to a week in the first fermentation, you should begin to see a layer of pellicle forming on the top of the liquid. While a bit gross looking, it is perfectly healthy and normal for your brew!
Keep a look out for any mold that may appear on top of your brew. Mold usually looks green, white, or reddish and is fuzzy. It is more likely to appear if you brew in a cold environment and can be dangerous to your batch! If mold appears, immediately throw away your entire batch, thoroughly sanitize your brewing vessel, and begin again.
If you are unsure if you have mold, have another ‘buch related question, or just want to show off your impressive fizz, check out the Kombucha subreddit and join the ‘buch community!
Yours Maia Schoenberg (Crowd Buch specialist)
Try Our tasty raw, fermented Kombucha from Cultcha Kombucha here:
Do you want to dive deeper?
Villarreal-Soto, S.A., Beaufort, S., Bouajila, J., Souchard, J.P., & Taillandier, P. (2018). Understanding Kombucha Tea Fermentation: A Review. Journal of Food Science, 83(3).