How Is Kombucha Made? A Step-by-Step Guide to Kombucha Fermentation

Kombucha is made by fermenting sweetened tea with a SCOBY  a living culture of bacteria and yeast. But there is much more to the process than simply adding a SCOBY to tea. Discover how kombucha is brewed, fermented, flavoured and naturally carbonated, and why time matters.

Kombucha starts with a surprisingly simple combination: tea, water, sugar, a SCOBY and time.

Through fermentation, these simple ingredients are transformed into a complex, lightly sparkling drink with a distinctive balance of acidity, sweetness and flavour.

But how does kombucha actually go from a cup of sweetened tea to the bottle you find in your fridge?

At Vesna, we take a slow, small-batch approach to kombucha brewing. Our kombucha is brewed in glass, unpasteurised and given approximately 21 days to ferment before it becomes the drink you pour into your glass.

Here's what happens along the way.

What ingredients are used to make kombucha?

Traditional kombucha starts with a handful of basic ingredients:

• Tea — usually black tea, green tea or a combination
• Water
• Sugar
• SCOBY — a Symbiotic Culture of Bacteria and Yeast
• Starter kombucha — already-fermented kombucha that helps establish the right environment for fermentation

Additional ingredients can then be used to create different flavours.

At Vesna, we work with botanicals including hibiscus, rose, elderflower, chamomile, holy basil, cucumber, lemon balm, ginger and lemon.

The beauty of kombucha is that the base is simple, while the possibilities for flavour are almost endless.

Step 1: Brewing the tea

Every kombucha starts with tea.

Tea is brewed in water to extract its flavour and compounds before sugar is added.

Black and green tea are particularly common choices for kombucha because they provide the characteristics needed to support the fermentation process.

The type of tea matters.

It influences the flavour of the finished kombucha, creating the foundation underneath everything else.

A green tea kombucha can feel fresh and delicate, while black tea can create a deeper, more rounded base.

For us, the tea isn't simply an ingredient in the background.

It's where the kombucha begins.

Step 2: Adding sugar

Once the tea has been brewed, sugar is added.

This can seem surprising if you're trying to understand kombucha, especially because a finished kombucha doesn't necessarily taste particularly sweet.

That's because sugar plays an important role during fermentation.

The yeasts in the SCOBY culture use sugars as part of their activity, transforming the sweetened tea as fermentation progresses.

This is one of the reasons the finished drink tastes so different from the sweet tea it started as.

The fermentation process changes the character of the drink.

Step 3: Adding the SCOBY

Next comes the ingredient that makes kombucha fermentation possible: the SCOBY.

SCOBY stands for Symbiotic Culture of Bacteria and Yeast.

Rather than being a single organism, a SCOBY is a living community of microorganisms that work together during fermentation.

When the SCOBY is added to the sweetened tea, fermentation begins.

If you've ever seen a kombucha SCOBY, you'll know it doesn't look particularly glamorous.

It can look like a pale, rubbery disc floating on top of the tea.

But this unusual-looking culture is at the heart of the entire process.

Step 4: Primary fermentation

Now comes the part that requires the most patience.

The sweetened tea and SCOBY are left to ferment.

During fermentation, microorganisms in the culture transform components of the sweetened tea. The flavour gradually develops, becoming less like sweet tea and more tart, acidic, aromatic and complex.

The exact fermentation time can vary.

Temperature, tea, sugar concentration, culture and desired flavour all influence how quickly fermentation progresses.

This is why there isn't one universal recipe for making kombucha.

Two batches made with the same ingredients can develop differently.

And that's part of what makes fermentation so fascinating.

How long does kombucha take to ferment?

There isn't one fixed answer.

Many kombucha recipes use a first fermentation lasting somewhere around one to two weeks, although fermentation time can vary considerably depending on the conditions.

At Vesna, we take a slower approach and allow our kombucha to develop over approximately 21 days.

Why?

Because we don't believe fermentation should be rushed simply to make a product faster.

As the kombucha ferments, its flavour evolves.

The tea becomes more complex. Acidity develops. The sweetness changes. Botanical ingredients can begin to create a more layered flavour profile.

Time is part of the recipe.

Step 5: Creating the flavour

Once the base kombucha has developed, it's time for flavour.

This is where we can introduce carefully selected fruits, herbs, flowers and spices.

At Vesna, our flavours are inspired by the ingredients themselves rather than artificial flavourings.

For example:

Glow

Hibiscus, rose & elderflower

Floral, vibrant and refreshing.

Calm

Chamomile, holy basil & cucumber

Soft, botanical and sophisticated.

Clarity

Green tea & lemon balm

Fresh, herbaceous and clean.

Energy

Ginger & lemon

Bright, zesty and warming.

The ingredients don't simply make kombucha taste different.

They create an entirely different drinking experience.

Step 6: Second fermentation and natural carbonation

If you've ever wondered why kombucha is fizzy, this is where things get interesting.

After the first fermentation, kombucha can be bottled for a second stage of fermentation.

During this stage, naturally occurring yeasts can continue to interact with remaining sugars. In a sealed bottle, the resulting carbon dioxide becomes dissolved in the drink.

That's where the gentle natural fizz comes from.

This is why kombucha can behave differently from a conventional carbonated soft drink.

You may notice:

• Different levels of fizz between bottles
• A little sediment
• Small bubbles rising through the drink
• Changes in flavour over time

These can all be characteristics of a fermented drink.

Step 7: Bottling and chilling

Once the kombucha has reached the desired flavour and carbonation, it is bottled and kept chilled.

Because Vesna kombucha is unpasteurised, refrigeration is an important part of how we handle and store the finished drink.

Cold temperatures help slow down the fermentation process.

We recommend keeping Vesna kombucha refrigerated and following the storage guidance on the bottle.

Why does kombucha taste sour?

If you're new to kombucha, you might be surprised by its acidity.

That's completely different from a typical soft drink.

During fermentation, the drink develops organic acids, creating the characteristic tangy, tart flavour associated with kombucha.

The final taste depends on many factors, including:

• The type of tea
• Fermentation time
• Temperature
• Sugar levels
• The culture
• Botanical ingredients
• The length of secondary fermentation

This is why kombucha can range from delicate and floral to sharp, citrusy, earthy or warming.

Why does kombucha sometimes have sediment?

You might occasionally see something floating in your kombucha or notice a small amount of sediment at the bottom of the bottle.

For a fermented drink, this isn't necessarily unusual.

Small particles can come from the tea, botanical ingredients or fermentation itself.

At Vesna, we don't filter our kombucha to the point where everything natural has been removed.

So if you see a little variation from bottle to bottle, that's part of the character of a small-batch fermented drink.

It's not supposed to look like a perfectly uniform soft drink.

Raw vs pasteurised kombucha

Another important part of understanding how kombucha is made is knowing what happens after fermentation.

Pasteurisation uses heat to reduce microorganisms in a food or drink.

An unpasteurised kombucha hasn't undergone that heat treatment after fermentation.

Vesna kombucha is raw and unpasteurised, meaning we keep our drink alive.

Because kombucha is a fermented product, it needs to be treated differently from a conventional shelf-stable soft drink.

That's why Vesna bottles are kept refrigerated at all times.

Why we don't rush our kombucha

There are ways to make production faster.

That's not what we're interested in.

Vesna was inspired by the kombucha our founder grew up with in Ukraine — homemade, shared and made with patience.

Today, we continue that spirit in small batches in the UK.

Our kombucha is:

Small-batch
Made in limited quantities rather than produced on an industrial scale.

Glass brewed
Our fermentation takes place in glass.

Unpasteurised
We don't heat-treat the finished kombucha.

Approximately 21 days fermented
We allow time for the flavour to develop.

Made with real ingredients
Our flavours come from carefully selected teas, botanicals, fruit and spices.

Because for us, fermentation isn't just a production method.

It's part of the craft.

So, how is kombucha made?

In simple terms:

Tea → Sugar → SCOBY → Fermentation → Flavour → Bottling → Natural carbonation → Chilling

But behind those simple steps is a living fermentation process that changes with time, temperature, ingredients and care.

And that's exactly why we find kombucha so fascinating.

You start with tea.

You give it time.

And something completely different emerges.

Discover Vesna Kombucha

If you'd like to experience traditionally fermented kombucha for yourself, explore the Vesna collection.

From hibiscus, rose & elderflower to ginger & lemon, each flavour begins with carefully brewed tea and develops through a slow fermentation process.

Small-batch. Glass brewed. Unpasteurised. Made with time.

Discover Vesna Kombucha →