Kombucha contains measurable alcohol, because the yeasts in its culture turn sugar into ethanol during fermentation. A laboratory analysis of 18 commercial kombuchas, published in 2017, found between 1.12 and 2.00 percent alcohol by volume, and the level kept moving after the bottles were sealed.
Two thresholds frame the question: 0.5 percent, the line at which United States federal rules treat a drink as an alcohol beverage, and 1.2 percent, the level above which European Union rules require the strength to be printed on the label. This page sets out how the ethanol forms, why it rises in storage, what each rule requires, what an Irish regulator found in 2021 and where the evidence stops. No Belgian national rule is cited, because none could be verified from an official text.
What puts alcohol into kombucha, and how much does a bottle hold?
Kombucha is sweetened tea fermented by a culture of yeasts and bacteria, and the yeasts turn part of the sugar into ethanol and carbon dioxide. A 2017 analysis of 18 commercial products, published in Food Analytical Methods, found ethanol between 1.12 and 2.00 percent by volume, so every sample sat above 0.5 percent.
The culture, often called a SCOBY for symbiotic culture of bacteria and yeast, runs two linked processes. Yeasts produce ethanol, and acetic acid bacteria convert part of that ethanol into acetic acid, which gives kombucha its sharpness. The ethanol left in a finished drink is therefore a balance between production and conversion, and the balance moves with sugar content, temperature and time. The paper, by Mohsen Talebi, Lillian Frink, Rahul Patel and Daniel Armstrong, carries this idea in its title, which describes the ethanol content of commercial kombucha as varied and changing. A single figure for kombucha, whether 0.5, 1 or 2 percent, describes one bottle on one day and not the category.
Why can the alcohol level rise after the bottle is sealed?
An unpasteurised kombucha keeps fermenting inside the bottle, so ethanol can keep rising after filling. In the 2017 study, bottles kept for 60 days at 4 °C and at 22 °C both showed a significant rise in ethanol, and the room-temperature series peaked at 1.57 percent after 14 days.
The refrigerated series rose gradually over the first 14 days and then stayed almost level, while the room-temperature series fell back slightly by day 21. The Food Safety Authority of Ireland (FSAI) makes the same point from the market side in its September 2021 guidance for unpasteurised fermented plant-based products: fermentation can continue during handling and storage, and alcohol can build up as it does. The practical reading, offered as a reading and not as a finding, is that a measurement taken at bottling and one taken on the shelf can differ, and that temperature and time in the supply chain belong in the explanation of any alcohol figure.
Where does the 0.5 percent line come from in United States rules?
Under the Alcohol and Tobacco Tax and Trade Bureau (TTB), kombucha with 0.5 percent or more alcohol by volume is an alcohol beverage. The test applies at any time during production, at bottling or after bottling, and kombucha that never reaches 0.5 percent falls under Food and Drug Administration (FDA) rules instead.
The TTB guidance page, last updated on 29 March 2019, adds that covered kombucha must be made on premises qualified by TTB, carry the federal health warning and meet tax, labelling and formula requirements. The same threshold governs wording. A TTB presentation on low and no alcohol products states that malt beverages may be called non-alcoholic only below 0.5 percent, with no tolerance, and alcohol free only at 0.0 percent. The line therefore works in both directions: it decides whether a producer is regulated as an alcohol maker and whether a bottle may carry a non-alcoholic claim.
What does the EU 1.2 percent rule require on a label?
Regulation (EU) No 1169/2011 requires the actual alcoholic strength by volume to be stated on beverages containing more than 1.2 percent alcohol by volume. Below that level the rule requires no strength statement, so a kombucha at 1.1 percent carries no mandatory figure although it holds more than twice the American 0.5 percent line.
Annex XII of the regulation fixes the form of the statement: a figure with no more than one decimal place, followed by the symbol "% vol.", measured at 20 °C. Tolerances sit in the same annex and run from 0.3 to 1.5 percent vol depending on the drink category, from 0.3 for the residual group of other beverages above 1.2 percent to 1.5 for drinks containing macerated fruit or plant parts. As an EU regulation it applies directly in every member state, Belgium included. The 1.2 percent figure is a disclosure threshold and not a definition of what counts as alcohol-free.
What did the 2021 Irish survey of fermented drinks find?
The FSAI tested 32 unpasteurised plant-based fermented drinks, among them kombucha, water kefir and ginger soda, and reported in September 2021 that 4 of them, or 13 percent, contained undeclared alcohol above the 1.2 percent labelling threshold, at levels between 1.5 and 3.9 percent.
The published result is not broken down by product, so the share of kombucha among the four drinks is unknown and no figure for kombucha alone can be drawn from it. What the survey does show is a gap between what a label declared and what a bottle held, in a category where the label requirement exists precisely because the level can exceed 1.2 percent. The FSAI followed the survey on 23 September 2021 with food safety guidance for producers of these drinks. The data are from 2021 and are presented here as such, not as the present state of the Irish market.
Can one bottle count as alcohol in the United States and need no strength statement in the EU?
Yes, in principle, because the two rules measure different things at different levels. The American line decides whether a drink is regulated as an alcohol beverage from 0.5 percent, while the European line decides whether a strength must be printed above 1.2 percent. A bottle between the two lines meets the first test and escapes the second.
| Rule | Threshold (% vol) | What it triggers |
|---|---|---|
| United States, TTB alcohol beverage test | 0.5 or more | Alcohol beverage rules: qualified premises, federal health warning, tax and labelling |
| United States, non-alcoholic claim on a malt beverage | Below 0.5, no tolerance | Wording "non-alcoholic" allowed |
| United States, alcohol free claim on a malt beverage | 0.0, no tolerance | Wording "alcohol free" allowed |
| European Union, Regulation 1169/2011 | More than 1.2 | Alcoholic strength must be stated on the label in % vol. |
A calculation shows how wide the gap is. The lowest of the 18 products in the 2017 study, at 1.12 percent, holds 2.24 times the American 0.5 percent line (1.12 divided by 0.5) and still sits under the European 1.2 percent threshold. The surprising consequence is that the lightest commercial kombucha in that sample would be an alcohol beverage under American federal rules while a European label would owe no strength statement at all.
What do these figures not establish?
The figures describe sampled products at specific dates and do not give a typical alcohol level for kombucha today. The 2017 analysis covers 18 commercial products, the 2021 survey covers 32 drinks available on the Irish market, home brewing is outside both, and the American and European thresholds regulate different things.
| Source | Samples (number) | Alcohol measured (% vol) |
|---|---|---|
| Talebi and colleagues, 2017, commercial products | 18 | 1.12 to 2.00 |
| Same study, bottles stored at 22 °C | Two series, 60 days | Peak of 1.57 after 14 days |
| Same study, bottles stored at 4 °C | Two series, 60 days | Gradual rise over 14 days, then nearly level |
| FSAI survey, 2021, undeclared alcohol above 1.2 | 4 of 32 drinks | 1.5 to 3.9 |
Nothing here is a statement on health, safety or suitability for any group of drinkers. The definition of alcohol-free also differs from country to country, which is why the page on what 0.0, alcohol-free and low-alcohol mean on a label treats the vocabulary separately. For the product side of the category, the premium kombucha guide and the comparison of water kefir and kombucha cover styles and producers.
Does kombucha contain alcohol?
Yes. Yeasts in the culture turn sugar into ethanol during fermentation. A 2017 analysis of 18 commercial kombuchas measured between 1.12 and 2.00 percent alcohol by volume, and the level can rise further in the bottle.
Is kombucha alcohol-free?
Not by definition. United States rules treat kombucha at 0.5 percent or more as an alcohol beverage, and a malt beverage may be called non-alcoholic only below 0.5 percent. A kombucha that stays below that line at every stage is regulated as a food.
At what level must an EU label show the alcohol content of kombucha?
Above 1.2 percent alcohol by volume. Regulation (EU) No 1169/2011 then requires the strength in % vol. with no more than one decimal place, measured at 20 °C. Below 1.2 percent no strength statement is required.
Can the alcohol in kombucha increase after bottling?
Yes, in unpasteurised products. In a 2017 study, ethanol rose significantly over 60 days at both 4 °C and 22 °C, and the Irish FSAI states that fermentation can continue during handling and storage.
Sources
- Alcohol and Tobacco Tax and Trade Bureau, Kombucha: general requirements (page last updated 29 March 2019): 0.5 percent or more alcohol by volume, applicable during production, at bottling or after bottling, FDA rules below the threshold. Consulted 23 October 2026.
- Alcohol and Tobacco Tax and Trade Bureau, Federal Regulation of Low and No Alcohol Beverages (presentation, citing 27 CFR 7.65): non-alcoholic below 0.5 percent and alcohol free at 0.0 percent for malt beverages, no tolerance. Consulted 23 October 2026.
- Talebi M, Frink LA, Patel RA, Armstrong DW, Examination of the Varied and Changing Ethanol Content of Commercial Kombucha Products, Food Analytical Methods 10, 4062 to 4067 (2017), DOI 10.1007/s12161-017-0980-5: 18 products, 1.12 to 2.00 percent, 60-day storage at 4 °C and 22 °C. Consulted 23 October 2026.
- Food Safety Authority of Ireland, survey of plant-based fermented beverages available on the Irish market (September 2021) and Food safety guidance published for unpasteurised fermented plant-based products (23 September 2021): 32 samples, 4 (13 percent) with undeclared alcohol of 1.5 to 3.9 percent, 1.2 percent labelling threshold. Consulted 23 October 2026.
- Regulation (EU) No 1169/2011 of 25 October 2011 on the provision of food information to consumers, Annex XII on alcoholic strength (EUR-Lex; Annex text consulted through the legislation.gov.uk copy of the EU text). Consulted 23 October 2026.
- Calculated figure: 1.12 divided by 0.5 gives 2.24.
The best-documented answer is a range and not a number: commercial kombucha measured between 1.12 and 2.00 percent alcohol by volume in 2017, and unpasteurised bottles can gain ethanol after filling. Whether that counts as alcohol depends on the rule applied, 0.5 percent in American federal law or 1.2 percent for a European label.
zeroproof.one follows the category with the source and the date attached to each figure. The Journal holds the reference pages on fermented drinks, labels and national markets.