In the Kitchen

Water kefir brewing

Water kefir brewing

CostFree to Low

Includes: Kefir grains (often free) plus sugar, water and fruit Example: Under 1 per litre batch

What it is

The translucent jelly-like grains that make water kefir are not grains at all. They are living colonies of bacteria and yeast, a community that grows, multiplies, and can be passed between people indefinitely, which is why some cultures in circulation today trace back generations.

Water kefir brewing is the practice of fermenting sugar water with these grains to make a lightly fizzy, mildly sweet probiotic drink. The grains feed on the sugar and, over one to two days, convert it into a tangy effervescent liquid full of live cultures. Unlike kombucha, it ferments fast and carries no tea or vinegar sharpness, which makes it gentler and quicker.

The cycle is short and forgiving. You dissolve sugar in water, add the grains, and leave it covered for 24 to 48 hours at room temperature. Strain out the grains, and you have a first ferment ready to drink or bottle. A second ferment with fruit juice or dried fruit builds carbonation and flavour, turning a plain base into something close to a natural soda.

Most people are struck by how cheap it becomes. The grains multiply, so after the first batch the only ongoing cost is sugar, a few cents per litre, against €2 or more for shop-bought probiotic drinks. The honest trade-off is commitment; the grains need feeding every couple of days or they starve, though they tolerate a fridge holiday for a week or two.

How it works

The grains are living creatures, and treating them as such is the whole practice. Water kefir grains, the translucent crystals that look a little like soft glass, feed on sugar and multiply as they ferment. Buy them live from a supplier rather than dehydrated if you want a faster start.

Dissolve roughly 50g of unrefined sugar into a litre of non-chlorinated water, because chlorine harms the grains. Rapadura or a light brown sugar works better than pure white, since the grains thrive on the trace minerals. Add the grains, cover with a cloth secured by a band rather than a tight lid, and leave at room temperature for 24 to 48 hours. Metal can react with the culture, so use a plastic or wooden spoon and a glass jar.

You will see tiny bubbles rising and the liquid turning slightly cloudy and less sweet as the grains eat the sugar. Taste at 24 hours. It should be mildly tangy and a little fizzy, not sweet like the start. Strain the grains out through a plastic sieve, and they are ready to start the next batch immediately.

For fizz, do a second ferment: bottle the strained liquid with a little fruit or juice, seal tightly, and leave a further 24 hours for carbonation to build.

Benefits

Gut Health & Probiotics Budget Alternative to Fizzy Drinks Fermentation Understanding Sustainable Kitchen Practice Creative Flavour Combinations Healthy Drink at Home

What you need

Here's what to gather before you start. The essentials are marked.

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Water kefir grains
White sugar or coconut sugar
Filtered or mineral water
Wide mouth glass jar

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Wide mouth glass jar

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Plastic strainer (metal can damage grains)

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Plastic strainer

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Swing top glass bottles for second ferment

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Swing top glass bottle

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Dried fruit or minerals
Fruit juice or ginger for flavouring

FAQs

They're a living culture of bacteria and yeast that looks like small translucent crystals, and they ferment sugar water into a light fizzy drink. You can't make them from scratch, so you get them from someone who already brews or buy them online for around €8-12. Once you have them, they multiply, so it's a one-time cost. Treat them as a pet you feed sugar.

It matters a lot. Use plain white or unrefined cane sugar, not honey (antibacterial, harms the grains) or zero-calorie sweeteners (no food for them). The water should be unchlorinated, since chlorine kills the culture, so either filter tap water or leave it out overnight to off-gas. The grains also like trace minerals, so an occasional pinch of unrefined sugar or a piece of dried fig feeds them well.

24 to 48 hours for the first ferment, depending on warmth. Taste it: it should be lightly sweet and a bit tangy, not syrupy (under-done) or sharp and vinegary (over-done). Strain out the grains, then do an optional second ferment in a sealed bottle with fruit or juice for 1-2 days to build fizz. Warmer rooms speed everything up.

Fizz comes from the sealed second ferment, not the first. The first stage is open and won't carbonate much, so to get bubbles, strain the kefir into a swing-top bottle, add a little fruit or juice for the yeast to eat, seal it tight, and leave it 1-2 days at room temperature. Burp the bottle daily, because trapped pressure can build fast and bottles can burst if left too long.

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