Home-brewed kombucha is a lovely thing to have on the go: a tangy, lightly fizzy fermented tea that you can flavour however you like, made from sweet tea and a living culture called a SCOBY. Once you have a SCOBY, each batch gives you the starter for the next, so it just keeps going.
It's genuinely easy, but there are two things to respect: keep everything clean and acidic so the culture stays healthy, and treat the fizzy bottling step with care, because sealed bottles build real pressure. The recipe is below, with the safety and the how-it-works underneath it.
How to Make Kombucha: A UK Beginner's Guide
Makes About 2 litres; 7 to 14 days to ferment, plus 2 to 4 days for the fizz
Makes
About 2 litres; 7 to 14 days to ferment, plus 2 to 4 days for the fizz
Ingredients
The sweet tea
For the ferment
For the fizz (optional, per bottle)
Method
- 1
Boil about a third of the water and use it to steep the tea and dissolve the sugar.
- 2
After 10 to 15 minutes, lift out the tea, top up with the rest of the water cold, and leave it to cool to room temperature. It must be below 30°C before the SCOBY goes in, as heat will kill it.
- 3
Pour the sweet tea into a clean, wide-mouthed glass jar. Add the starter liquid, then the SCOBY, using clean hands and no metal.
- 4
Cover the jar with a tightly-woven cloth or a piece of kitchen paper held on with a band, so it can breathe but flies stay out. Never seal the first ferment.
- 5
Leave it somewhere warm, ideally 20 to 26°C, out of direct sun and undisturbed, for 7 to 14 days. A cool UK room sits at the slow end, so give it the longer time.
- 6
From day 5, taste a little through a straw down the side of the jar. It's ready when it has tipped from sweet to pleasantly tart, like a sharp sparkling apple drink, before it turns fully vinegary.
- 7
Lift out the SCOBY along with about 200ml of the liquid and set it aside; that's your starter for the next batch.
- 8
For fizz, bottle the rest in strong flip-top or PET bottles, adding a little fruit, juice or ginger to each and leaving a small gap at the top.
- 9
Seal and leave at room temperature for 2 to 4 days until fizzy, burping the bottles daily, then move them to the fridge. Read the safety note below before this step.
Cook’s notes
- Timings: about 20 minutes of hands-on work, then 7 to 14 days for the first ferment and 2 to 4 days for the fizz.
- Safety, the fizz step: a sealed second ferment builds real pressure and glass bottles can crack or explode. Use strong flip-top or, safest, food-grade PET bottles; burp them daily (or squeeze a PET bottle to feel when it's rock-hard); and refrigerate as soon as it's fizzy. Don't over-sweeten, don't leave sealed bottles warm for long, and open chilled bottles slowly over a sink.
- The SCOBY eats the sugar, not you: it turns most of it into gentle acids and fizz, so the finished drink is far less sweet than the tea starts out. Don't cut the sugar to make it 'healthier', as the culture needs it as food.
- Keep a SCOBY hotel: store spare SCOBYs in a covered glass jar topped up with mature kombucha at room temperature. It's your backup and your starter bank, and it keeps going indefinitely if fed.
- Storage: refrigerate once it's fizzy, as the cold all but stops the ferment and holds the flavour. It's best within about a month.
What you’ll need
- Large wide-mouthed glass jar (about 2.5 litres)
- A tightly-woven cloth or kitchen paper, and a band
- Strong flip-top or food-grade PET bottles, for the second ferment
- A non-metal spoon, keep reactive metal away from the culture
Troubleshooting
There's fuzzy mould on top.
This is the one thing you can't rescue. Fuzzy, dry patches of blue-green, white or black mould mean you throw away the whole batch and the SCOBY, sterilise everything, and start again. Never try to salvage it.
It's gone too sour.
It over-fermented. Give it fewer days next time, or dilute it to drink. An over-sour batch makes excellent starter liquid for the next one.
It has no fizz.
The fizz only comes from a sealed second ferment. Bottle it airtight with a little fruit or sugar and leave it somewhere warm for a couple more days, and check your bottles actually seal.
It's still sweet after two weeks.
It's too cold. Move it somewhere warmer, 20 to 26°C, and add a little more mature starter next time to get it going faster.
There are brown, stringy bits under the surface.
That's yeast, and it's completely normal and healthy, as is a bumpy SCOBY or a new pale layer growing on top. Leave it be.
More about kombucha
What a SCOBY is. SCOBY stands for Symbiotic Culture Of Bacteria and Yeast: a rubbery, pale disc that hosts the microbes doing the fermenting. It grows a fresh layer with every batch, so you can share the spares or keep them as backup.
How the ferment works. The yeasts feed on the sugar and give off a little carbon dioxide, and the bacteria turn that into gentle acids. That acidity is what makes kombucha tangy and keeps spoilage organisms out, the same 'good bacteria protecting the food' principle behind sauerkraut. Most of the sugar is eaten by the culture, which is why the finished drink is far less sweet than the tea it started as.
Why the tea and sugar matter. The sugar is food for the culture, and the tea gives it the nitrogen and tannins it needs to stay strong. Plain white sugar with black or green tea is the reliable feed.
The two ferments. The first ferment is open, with the SCOBY, and does the souring. The second ferment is sealed, in bottles with a little fruit, and traps the carbon dioxide to make the fizz and the flavour.
The starter is your safety net. Adding mature, already-acidic kombucha at the start makes the brew too acidic for mould from the very first minute, which is the single most important habit for a safe, healthy batch.
Staying safe with the fizz
The sealed second ferment is the one genuinely hazardous step, because it builds real pressure and a glass bottle can crack or even burst. Use bottles made to hold fizz, strong swing-top or flip-top ones, or safest of all food-grade PET plastic bottles so you can feel the pressure by squeezing. Burp them daily by cracking the lid, and move them to the fridge the moment they're fizzy, as the cold stops the pressure building. Don't over-sweeten the second ferment, don't leave sealed bottles sitting warm, and open chilled bottles slowly over a sink. And the absolute rule: any fuzzy mould means the whole batch goes in the bin, no exceptions.
Frequently asked questions
Written by
UK Homesteading Team
Editorial team
The UK Homesteading editorial team, offering UK-specific, evidence-led guidance on growing, keeping, preserving and the law.
