About Water Kefir

Water kefir is a fermented drink produced by a community of bacteria and yeasts. On this page you can learn more about the science behind it — and why the network of these cultures is so unique.

Fermentation

Here you can find out why fermentation is an ancient principle that still appears in many everyday foods today.

1. What is fermentation?

Fermentation has been part of human food culture for thousands of years. Long before people knew that microorganisms existed, they were already using their activity to make food last longer, taste better, and become easier to digest.

Today, we know that fermentation is driven by bacteria, yeasts, or moulds that transform components of food, such as sugars, proteins, or fats, into new substances. In the process, they produce acids, gases, alcohol, and many aromatic compounds that shape the taste, smell, texture, and shelf life of fermented foods.

Fermentation is not the same as food spoilage. Spoiled food is changed by unwanted microorganisms and may become unpleasant or unsafe to eat. Fermentation, in contrast, relies on desired microbial growth. The microorganisms involved are used intentionally to create specific qualities, such as the acidity of sauerkraut, the bubbles in fermented drinks, or the characteristic flavours of cheese, bread, and soy sauce.

2. What types of fermented foods are there?

Historically, fermentation was mainly used to preserve food and make it safer. It helped people store perishable ingredients, reduce unwanted compounds, and make better use of available resources. At the same time, fermentation created entirely new flavours.

Many foods and drinks that are part of everyday life today would not exist in the same form without microorganisms: yogurt, cheese, sourdough bread, sauerkraut, kimchi, vinegar, coffee, cocoa, soy sauce, beer, wine, kombucha - and kefir. Fermented foods are therefore not a modern trend, but part of a long and diverse food tradition. They occur in many forms across the world and reflect local ingredients, practices, and eating habits.

3. Where does water kefir fit in?

Water kefir belongs to the group of fermented beverages. Unlike beer or wine, its main characteristic is not alcohol production. Instead, its flavour and quality are shaped mainly by lactic acid bacteria, acetic acid bacteria, and yeasts. These microorganisms live together in water kefir grains: small, translucent structures in which they are embedded in a matrix that they produce themselves.

When the grains are added to sugar water with dried fruits or other ingredients, fermentation begins. The microorganisms use the sugar as a source of energy and convert it into different metabolic products. The result is a mildly acidic, often gently sparkling drink with a complex flavour. Water kefir is therefore a vivid example of how simple ingredients can be transformed into something new through the activity of living microorganisms.

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Water Kefir

Here you can find out what water kefir is, where it may have come from, and how it differs from milk kefir and kombucha.

1. What is water kefir?

Water kefir is a fermented beverage made from water, sugar, dried fruit, and so-called water kefir grains. These grains are not grains in the literal sense, but rather small, translucent structures in which various microorganisms live together. Lactic acid bacteria, acetic acid bacteria, and yeasts work together to transform sugar water into a slightly sour, fizzy drink.

In terms of taste, water kefir often resembles a mild lemonade. Depending on how long it ferments, which ingredients are used, and which culture is involved, it can taste rather sweet, fruity, floral, lemony, or distinctly sour.

During fermentation, the aroma changes: the initially sweet mixture gradually develops into a more complex beverage with fresh, sour, and slightly fermented notes. The carbonation occurs naturally during this process. As the microorganisms break down the sugar, they produce various metabolic byproducts, including acids, flavour compounds, and carbon dioxide. This carbon dioxide is what gives the drink its gentle fizz. Small amounts of alcohol may also be produced. The alcohol content is significantly lower than that of beer or wine, yet water kefir is not strictly alcohol-free. This can be important, for example, for children, pregnant women, or people who wish to avoid alcohol.

Since water kefir is based on water, sugar, and plant-based ingredients, it is generally vegan. At the same time, it is a living and variable food: not every culture is the same, and home preparation also influences the taste, acidity, sweetness, and carbonation. It is precisely this diversity that makes water kefir so exciting. Each culture brings its own unique character to the table.

2. Is water kefir healthy?

Water kefir is often associated with potential health benefits. Scientific studies have investigated, amongst other things, its antioxidant, anti-inflammatory and metabolic properties. Furthermore, water kefir may contain probiotic microorganisms, including certain lactic acid bacteria and bifidobacteria, which are generally associated with supporting gut health.

However, many of these findings stem from laboratory experiments or animal studies and cannot automatically be applied to humans. Water kefir should therefore not be regarded as a ‘cure-all’. It is, above all, a fermented drink containing live microorganisms, a variety of flavours and a long tradition of production and passing down.

3. Where does water kefir originate?

It is impossible to say with certainty today where water kefir first originated. Unlike many industrially produced foods, water kefir does not have a clearly documented history of its origins. The cultures were presumably passed down from household to household over a long period of time, adapted and repeatedly restarted. In the process, precise information about their origins was easily lost. One frequently cited theory points to Mexico. There, kefir-like grains are said to have been found on the leaves of opuntias, or prickly pears. These plants can release sugar-rich sap, which serves as a food source for microorganisms. Microorganisms living in symbiosis may have developed in such natural habitats and were later used to produce fermented drinks.

Another trace leads to the Caucasus. There, similar structures known as ‘ginger beer plants’ were described in the 19th century. These, too, consisted of a solid, gelatinous community of microorganisms and were used to produce fermented drinks. However, it is not yet clear whether these cultures are directly related to modern-day water kefir grains.

It is also possible that water kefir does not have a single origin. Perhaps similar microbial communities arose in different places, were passed on, mixed and adapted to new ingredients and customs. As water kefir grains are living cultures, they change with their environment: with the sugar used, the fruit, the water, the temperature and the way people care for them.

Today, water kefir is found all over the world. It is shared, passed on and rediscovered time and again, particularly within fermentation communities. Every culture carries its own story within it, even if we often only know part of it.

4. How is it different from milk kefir & kombucha?

Water kefir is often compared to milk kefir and kombucha. This is understandable, as all three are fermented drinks produced by a community of bacteria and yeasts. These microorganisms do not live individually, but within a shared structure: in water kefir and milk kefir, this takes the form of so-called grains, crystals or nodules; in kombucha, it is a disc-like culture often referred to as a ‘Scoby’. Nevertheless, the three differ significantly.

Milk kefir is made from milk and is creamy, like a drinkable yoghurt. Kombucha is made from sweetened tea and is usually fermented for much longer. Water kefir, on the other hand, is based on sugar water with plant-based ingredients such as dried fruit. It is generally lighter, fizzier and has a more lemonade-like taste. Furthermore, the species of microorganisms involved and the structure in which they coexist differ.

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Recipe and Preparation

Here you can find out how to make water kefir at home and what to consider when choosing ingredients, fermenting, and storing it.

Ingredients

2–3 tbsp water kefir grains
500 mL water
3 tbsp sugar
approx. 20 g unsulphured, preservative-free dried fruit
optional: one slice of lemon without peel

Instructions

Step 1

Prepare the sugar water

Pour 500 mL of water into a clean container and stir in 3 tbsp of sugar until dissolved.

Step 2

Add the water kefir grains

Add 2-3 tbsp of water kefir grains to the mixture.

Step 3

Add the fruit

Add approx. 20 g of dried fruit, such as figs, dates, raisins or apricots. Optionally, add one slice of lemon without peel. Stir gently.

Step 4

Cover the container

Cover the container with a clean cloth, coffee filter or loosely placed lid. It should not be sealed airtight, so that the carbon dioxide produced during fermentation can escape.

Step 5

Leave to ferment

Leave the mixture to ferment at room temperature for 1-3 days. The longer it ferments, the less sweet and the more acidic the water kefir will become. Fermentation in the fridge is also possible, but it takes a little longer for the microorganisms to convert the sugar.

Step 6

Strain

Pour the mixture through a sieve to separate the water kefir grains from the liquid. Remove the dried fruit and lemon as well.

Step 7

Reuse the grains and share

Rinse the water kefir grains thoroughly with water and use them straight away for the next batch. Optionally, you can add a small splash of the finished liquid to the next batch. Over time, water kefir grains can grow and multiply. You can use excess grains to start new batches or give them away. If a new offshoot develops from your culture, you can register this connection on KefirConnect and help expand the network.

Step 8

Drink or optional second fermentation

You can drink the water kefir straight away or pour it into a sealable bottle for a second fermentation and store it in the fridge for a further 1-2 days. This may increase the carbonation. Open the bottle carefully, as pressure may build up.

Good to know

During fermentation, the microorganisms use the sugar as a source of energy. In the process, they produce acids, aroma compounds, carbon dioxide and small amounts of alcohol. The carbon dioxide creates the gentle fizz, while the acids give water kefir its fresh taste.

This basic recipe is intended as a guide. Water kefir is a living ferment, so the recipe can be adapted to your own taste. You can experiment with different types of sugar, dried fruits, fresh fruits or vegetables.

This recipe is not a fixed rule. Dried figs are often used because they provide additional nutrients for the microorganisms. However, other dried fruits, different types of sugar and additional ingredients can also work well. What matters is that the ingredients are not preserved or sulphured. If it tastes good and keeps the kefir microbes happy, it is worth trying.

If you want to take a break or are going away on holiday, you can store your water kefir in the fridge for a while. Prepare it as usual but add about one extra spoonful of sugar. In the fridge, fermentation slows down considerably, so the grains can be kept this way for up to 3 weeks. After the break, the water kefir may need a little time to become fully active again. It can take two to three fresh batches before the grains regain their full fermentation strength.

Tip

If you move far away from the basic recipe or experiment with new ingredients, it is a good idea to keep a backup batch. You can either prepare a small amount of water kefir using the standard recipe at the same time or keep some of your grains separate. That way, you have a safe reserve in case an experiment does not work out.

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Research

Here you can find out why water kefir is interesting for microbiological research and what makes its living grains so special.

1. Who lives in water kefir?

Water kefir is not just a fermented drink, but also a fascinating example of a stable microbial community. Its production involves not just a single species of microorganism, but an interaction between various bacteria and yeasts. The most important groups are lactic acid bacteria, acetic acid bacteria and yeasts.

In addition, other microorganisms such as bifidobacteria may also be present. The exact species living in a culture can vary from culture to culture. Each water kefir culture therefore has its own microbial composition but may well share similarities with other cultures.

2. How do the microorganisms work together?

Despite these differences, water kefir cultures function with remarkable reliability. This is because the microorganisms do not live independently of one another but interact with each other. Yeasts, for example, can break down sugar and release substances that are then utilised by bacteria. Lactic acid bacteria produce organic acids and help the mixture to become sour more quickly. Acetic acid bacteria, amongst other things, can convert alcohol into acetic acid.

Together, they produce the typical characteristics of water kefir: a fresh, tangy taste, slight carbonation, flavour compounds and small amounts of alcohol. This results in a sort of microbial division of labour. Some microorganisms produce substances that others can utilise. Others alter the environment, for example by forming acids, thereby creating conditions under which the community remains stable.

These interdependencies make water kefir particularly interesting for research: it demonstrates how different microorganisms can coexist, compete with one another and, at the same time, support one another.

3. What makes water kefir grains so special?

Water kefir grains play a special role. They are stable biofilms made up of several species of microorganisms. The microorganisms live embedded within a gel-like matrix that they themselves produce. From the outside, the grains usually appear transparent to milky-white, soft and slightly elastic. Inside, the microorganisms are spatially organised. This creates small habitats with varying conditions, for example in terms of nutrients or oxygen. It is precisely this structure that makes water kefir grains so special. They protect the microorganisms, facilitate their cooperation and help to ensure that the community is maintained over many fermentation cycles.

At present, water kefir grains cannot be produced artificially. It is not possible to simply reassemble them from individual microorganisms in a laboratory. The only way to propagate them is to allow existing grains to grow and be passed on. It is also worth noting that water kefir cultures are robust, even though their exact composition varies from culture to culture. It appears that different species can perform similar roles. This phenomenon, where core functions are covered by multiple species, is known as functional redundancy. As a result, the community can remain stable even if the abundance of individual species changes or varies between cultures.

Water kefir is therefore a valuable model system for research: it helps us understand how complex microbial communities arise, remain stable, adapt and can be passed on from person to person over long periods of time.

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Join

Here you can find out how your water kefir culture can become part of KefirConnect and help us explore this living network.

Researching Together: Citizen Science Meets Water Kefir

Citizen Science means that people outside traditional research institutions actively contribute to scientific projects. They collect data, share observations, provide samples, or contribute their own knowledge and experience. This makes it possible to investigate research questions that would be difficult to address without the involvement of many people.

No scientific training is needed to take part. On the contrary: Citizen Science projects depend on the participation of many different people. In this way, Citizen Science connects scientific research with everyday experience. Participants are not simply treated as a source of data, but as important partners in the research process. At the same time, science can become more transparent and accessible: people gain insight into how research works, why data matter, and how many individual contributions can come together to create shared knowledge.

This is exactly where KefirConnect comes in. Water kefir cultures are usually cared for, shared, and passed on privately: often through circles of friends, families, or local fermentation groups. This creates a living network that has so far remained largely invisible. With KefirConnect, we want to work together to record where water kefir cultures live, how they are passed on, and which stories are connected to them.

Every registered culture helps to make this network visible step by step. By taking part, you help us draw a bigger picture: Where do water kefir cultures come from? How are they shared? How large can these networks become? And how stable does a microbial community remain as it passes through many hands?

How the project works

KefirConnect is structured in two project phases. In the first phase, we want to make visible where water kefir cultures live and how they are connected. Participants can register their own culture on the map and indicate where it came from or who they have shared it with. Step by step, this creates a network of water kefir cultures that shows how these living communities are shared, passed on, and connected.

In the second project phase, we want to take a closer look at selected cultures. For this, samples will be collected and analysed in the laboratory. We are interested, for example, in which microorganisms are present in different water kefir cultures, how similar or different related cultures are, and how stable a microbial community remains when it is cared for over time and passed from household to household. The map from the first phase will help us investigate these connections in a more targeted way.