What is kombucha?
Kombucha is a fermented tea drink. You brew sweetened tea, add a living culture, and leave it to ferment for a week or more. The culture turns most of the sugar into organic acids, which is where kombucha gets its tang. The result is tart, lightly sweet and fizzy, somewhere between a sparkling apple cider and a very mild vinegar.
That is the short answer. Here is what sits behind it.
What is kombucha made of?
Four things: tea, sugar, water and a culture. That is the whole list for a traditional brew.
The tea matters more than most people expect. Cheap kombucha is often made with tea dust and fannings, the broken scraps left after grading, because they are cheap and ferment fast. Whole leaf tea costs more and takes longer, but it carries flavour the dust cannot. We brew with organic whole leaf Assam.
The sugar is food for the culture rather than an ingredient you taste at the end. Most of it is consumed during fermentation. What is left is what gives the finished drink its slight sweetness.
What is a SCOBY?
SCOBY stands for symbiotic culture of bacteria and yeast. It is the pale, rubbery disc you see floating on top of a home brew, and it is a mat of cellulose the bacteria build themselves. The yeasts turn sugar into carbon dioxide and small amounts of alcohol, and the bacteria turn most of that alcohol into organic acids, mainly acetic acid. Those acids are the tang.
We have written about this in more detail in what is a SCOBY and why does every kombucha need one.
How long does kombucha take to make?
A first fermentation usually runs somewhere between one and three weeks, depending on temperature and how tart the brewer wants it. Warmer means faster and sharper. Many brewers then do a second, shorter fermentation with fruit, herbs or spices to build flavour.
Ours ferments in small batches on French oak at our railway arch in Glasgow, which is slower than stainless steel and gives a rounder, softer finish.
What does kombucha taste like?
Tangy and bright, with a sharpness that catches people out the first time. It is closer to dry cider or a soft drink made for adults than to cola or squash. Underneath the fruit or botanicals there is a tea character, which is why the quality of the tea shows up so clearly in the glass.
Flavour varies enormously between brands and batches. If you have tried one kombucha and disliked it, that is worth knowing before you write off the category. You can see how ours differ on our kombucha flavours page.
Does kombucha contain caffeine or alcohol?
Both, in small amounts, and both for the same reason: it is made from tea and it is fermented.
Caffeine is typically around a third of what you would get in a regular cup of black tea. Alcohol is a natural by-product of fermentation, and traditionally fermented kombucha contains a trace of it, up to 0.5% ABV. If you need to avoid alcohol completely, choose a drink labelled 0.0%.
What is raw kombucha?
Raw means unpasteurised. Pasteurising heats the drink, which makes it easier to ship and store but takes the edge off the flavour and kills the live cultures. A lot of supermarket kombucha is pasteurised for exactly that reason.
Ours is raw and unpasteurised, never heat treated. There is more on our raw kombucha page, and on what the Soil Association certification behind organic kombucha actually requires.
Where does kombucha come from?
Nobody can date it precisely. Most accounts trace it back a couple of thousand years to East Asia, where it was brewed at home rather than sold. It spread slowly through Russia and eastern Europe in the twentieth century, and arrived in Britain properly only in the last fifteen years or so, carried in on the wider interest in fermented food.
Kombucha or water kefir?
They sit side by side in the fridge and get confused constantly, but they are not the same drink. Kombucha is fermented tea made with a SCOBY over weeks. Water kefir is fermented sugar water made with small crystal-like grains over a day or two, and it tastes lighter and softer. We have compared them properly in the difference between kombucha and water kefir.
Our kombucha
We have brewed in a railway arch on Glasgow's south side since 2017. Organic whole leaf Assam, fermented on French oak, raw and unpasteurised, in five flavours. Our Original is a BBC Good Food Best Kombucha, 2026.
You can build a case of 12 in any mix you like, with free mainland UK delivery. If you would rather read first, our guide to kombucha and gut health goes through what the studies actually show.