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Strawberry water kefir
Level 1 · beginner
Strained water kefir with fresh crushed strawberries, in bottles made for fizz and straight into the fridge. It turns pink, gets a gentle fizz and is drunk within two days.
- Time
- 24–48h
- Temperature
- 34–40°F
- Bottles
- 1L
The golden rule: the drink already sour before it is bottled, bottles made for pressure, and never more than 48 h out of the fridge.
No sign-up. We guide you step by step, from the scale to the fridge.
Reviewed October 26, 2026 · 22 facts, each with its source
You'll need
- One 500 ml swing-top glass bottle, made for carbonated drinks
- One 500 ml PET soda bottle, the test bottle
- 1-liter glass pitcher
- Fork
- Wide-mouth plastic funnel
- Plastic strainer
- Calibrated pH meter
- Kitchen scale
Step by step
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Wash and sanitize the bottles
Wash the bottles, the cap, the pitcher, the fork, the funnel and the strainer with hot, soapy water and rinse them well. Sanitize the glass bottle with its gasket, the pitcher and the strainer by submerging them in water at 171 °F or hotter for at least 30 seconds. Only wash and rinse the PET bottle: water that hot warps it. The same goes for the funnel if its plastic can't take the heat.
Tip: A soda or sparkling water bottle works as the test bottle: it's made to hold pressure.
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Check the pH of the strained kefir
Use finished, freshly strained water kefir, the batch you were about to refrigerate: no longer sweet, no grains, and without the figs and lemon from the base. The more sugar it has left, the more gas it makes in the bottle. Check the pH with the calibrated meter: it must be 4.6 or below. If it reads higher, don't bottle it.
Tip: Don't add sugar: between what's left in the kefir and the strawberries' own, there's plenty.
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Wash and crush the strawberries
Use 120 g of fresh strawberries, whole and free of bruises or mold. Rinse them right before using them, hull them and cut them into quarters. Put them in the pitcher and crush them with the fork, without making a purée.
Tip: Very ripe strawberries give more color and flavor, but skip any soft or spotted parts.
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Mix, test again and bottle
Pour the kefir over the strawberries and stir. Check the pH again: it must still be 4.6 or below. Spoon the strawberries into the two bottles and fill them with kefir through the funnel. Leave 1¼–2 inches (3–5 cm) of air at the top and close them.
Tip: Write the date and time on both bottles, and move them to the fridge as soon as they're closed.
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Leave them in the fridge for 24 to 48 hours
Move the bottles to the fridge as soon as they're closed, at 40 °F or below, and leave them for at least 24 hours, as BCCDC does. From then on it's ready to drink. The longer it waits, the more fizz and alcohol it gets: drink it within 2 days of bottling. Squeeze the test bottle every day: in the fridge the gas builds slowly, but it builds.
Within a few hours it turns pink and the fruit rises. If you see green, blue, brown or black mold, or it smells rotten, throw it out.
Tip: Want more fizz? Don't take it out of the fridge: no guide says how many hours it can stay out, and water kefir ferments fast. With fruit, more days in the fridge don't pay off: it's drunk within 2.
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Open them cold and drink it within 2 days
Open it straight from the fridge: slowly, over the sink, with a towel on top and pointed away from your face. With fruit inside, it can foam up all at once. Pour it through the strainer. Drink it within 2 days of bottling: that's a house rule, the same one the guidelines give for kombucha with fruit.
Tip: Don't shake the bottle before opening it.
No sign-up. We guide you step by step, from the scale to the fridge.
Variations
The same method, a different flavor. Once you have this one down, try one of these.
What you'll see
This is the second fermentation of water kefir. Strained kefir, with the grains out, goes into bottles with crushed strawberries and spends 24 to 48 hours in the fridge before you drink it. That's how BCCDC does it, the only food safety guide that covers this second fermentation: with the fruit, inside the fridge, for at least 24 hours. In the cold, the yeast slowly keeps eating the sugar left in the kefir and the strawberries' own: it makes some fizz, and alcohol too. It ends up less fizzy than a kombucha with fruit, but there's no clock or bottle to watch, and water kefir, which ferments very fast out of the fridge, can't run away from you.
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How to tell it's going well
- Only with acidic, strained kefir. Bottle only kefir with the grains out and a pH of 4.6 or below, and test again once the strawberries are in.
- Bottles made for fizz, plus a PET test bottle. Swing-top or beer glass bottles, or PET soda bottles. Never jars or wine, oil or still water bottles: gas builds up, and the liquid can push out or the bottle can break. Squeeze the test bottle every day.
- Always in the fridge, from the moment you close the bottle. At 40 °F or below and for at least 24 hours, as BCCDC does. No guide gives hours for doing it out of the fridge, and water kefir ferments fast.
- Open it cold, slowly and away from your face. In Australia, a kombucha was recalled because the cap could pop off and injure.
- It has more alcohol than the kefir you started with, and it keeps gaining it in the fridge. Made with fruit juices, water kefir can go past 1% alcohol, and a strawberry one reached 2.4%. It's not for young children or during pregnancy.
- Drink it within 2 days. That's a house rule for kefir with fruit.
- Pasteurized juice only. If you swap the strawberries for juice, make it pasteurized.
Where every number comes from
Every number in this recipe comes from a food safety guide. We keep a copy of each source and quote its exact words.
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1
BCCDC does the second fermentation with fruit, strawberries included, once the grains are out and inside the fridge, for at least 24 hours
“Secondary fermentation steps that add additional fruit or fruit juices, for example, apple, pineapple, lime, lemon, mango, cherries, or strawberries occur after grain removal and should be performed in the refrigerator for at least 24 hrs.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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2
BCCDC cools strained kefir to 40 °F within 4 hours at most
“Cool to 4oC immediately, within 4 hrs (no longer than 6 hrs)”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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3
Final pH 4.6 or below, and never below 2.5
“Ensure the pH of final product is 4.6 or less, but not lower than pH of 2.5.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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4
Sanitize the strainer before each use
“Sanitize sieves before each use.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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5
Built-up gas can push the liquid out
“Excess pressure can build-up from carbon dioxide, causing fluids to leak out.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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6
Water kefir has a live culture and needs refrigeration
“Water kefir contains live culture and requires refrigeration.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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7
Once finished, into the fridge at 40 °F
“Once kefir production is deemed complete, it must be refrigerated at 4°C.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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8
Recommended labels, "Do not shake." and "Contents under pressure."
“Precautionary statements on bottles are recommended to advise consumers “Do not shake.” and “Contents under pressure.””
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
Show the remaining 14 claims
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9
Water kefir made with fruit juices can reach 1% alcohol or more
“Alcohol can be elevated in water kefir. Of concern, water kefir made from vegetable or fruit juices may contain high levels of alcohol (≥1%).”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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10
A strawberry water kefir reached 2.4% alcohol
“strawberry water kefir: 2.4%”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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11
It may contain alcohol, so it's not for young children or during pregnancy
“May contain alcohol. Not a suitable beverage for young children or during pregnancy.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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12
Pasteurized juice only
“Only use pasteurized milk and juice for fermentation media.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.12: Kefir, milk and water (December 2024) · read on October 25, 2026
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13
Sanitize in water at 171 °F or hotter for 30 seconds
“Submerge cleaned equipment in hot water (at least 171°F) for at least 30 seconds to sanitize.”
National Center for Home Food Preservation (USDA, University of Georgia) · Kombucha Tea · read on October 20, 2026
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14
Herbs and fruit are washed and handled so they don't contaminate the drink (BCCDC guidance for kombucha and jun)
“Other products added to change flavour (herbs, fruit, etc.) must be processed and handled in a manner that prevents contamination of the kombucha or jun, including washing and refrigeration where appropriate.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.11: Kombucha and Jun (September 2023, updated December 2024) · read on October 25, 2026
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15
Bottles that resist acid and pressure (BCCDC guidance for kombucha and jun)
“Glass bottles, cans or kegs should be resistant to acid leaching and pressure build-up.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.11: Kombucha and Jun (September 2023, updated December 2024) · read on October 25, 2026
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16
With too much gas, bottles and cans can rupture
“Excess formation of gas in bottles and cans may cause containers to rupture under added pressure.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.11: Kombucha and Jun (September 2023, updated December 2024) · read on October 25, 2026
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17
In kombucha and jun, added sugar and flavorings can produce excess alcohol
“Sugars and flavourings with added sugar added after this second step may cause formation of excess alcohol if fermentation persists.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.11: Kombucha and Jun (September 2023, updated December 2024) · read on October 25, 2026
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18
Leave 3–5 cm of air at the top (school ginger beer guide, practice)
“leaving a 3–5 cm air gap at the top”
Science in School (EIROforum), Dean Madden, National Centre for Biotechnology Education, University of Reading · Ginger beer: a traditional fermented low-alcohol drink (Issue 8, Spring 2008) · read on October 25, 2026
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19
Mold is usually green, blue, brown or black
“Mold is typically green, blue, brown, or black in color.”
UC Davis, Department of Food Science and Technology · Common issues with fermented fruits and vegetables (v1.0, 15-mar-2022) · read on October 20, 2026
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20
Once flavored, 2 days in the fridge (the figure for kombucha, which we use here too)
“Once flavors have been added kombucha should be stored under refrigeration and consumed within 2 days.”
University of Georgia Cooperative Extension (National Center for Home Food Preservation) · Crafting Kombucha at Home: Frequently Asked Questions (2026) · read on October 20, 2026
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21
A kombucha recalled because the cap could pop off and injure
“This product may cause injury due to cap popping off.”
NSW Food Authority · Recall: LoBros Lemon Lime and Bitters Kombucha, high pressure, cap may pop off (27 Feb 2019) · read on October 25, 2026
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22
In sealed bottles, a kombucha reached 1.6–1.7% alcohol after 30 days in the fridge
“After refrigeration for 30 days at 4 °C, ethanol content changed significantly (p < 0.05) in all samples and reached values of 13.41 ± 0.09, 13.10 ± 0.31, 12.84 ± 0.15 g/L or 1.70 ± 0.01, 1.66 ± 0.04, 1.61 ± 0.02% (v/v)”
Foods (MDPI), via PubMed Central · Kombucha Fermentation of Olympus Mountain Tea (Sideritis scardica) Sweetened with Thyme Honey (2023) · read on October 25, 2026
