The Expiration Question: Can Kombucha Go Bad?

May 9, 2025

You were so excited about that bottle of your favourite kombucha, carefully chosen for its unique flavour profile. But life got in the way, and somehow, it ended up tucked away in the back of your refrigerator. Now, during your monthly cleaning ritual, you've rediscovered it, like an archaeological find. But you wonder: Has this forgotten brew become a bacterial breeding ground? Is it still safe and delicious to drink?

This blog will help you understand kombucha’s shelf life and uncover the best storage practices. Learn whether kombucha can go bad, what signs to look for, and how to ensure that every sip is as refreshing as intended. Let’s pop the cap on the expiration question and see how long kombucha can last.

What is kombucha?

Kombucha is a fascinating fermented tea that has surged in popularity due to its unique taste and potential health benefits. At its heart, it's sweetened tea that undergoes a fascinating transformation through fermentation.

The fermentation magic: Fermentation begins by introducing SCOBY (Symbiotic Culture Of Bacteria and Yeast) to sweetened black or green tea. This SCOBY is a living matrix of beneficial microorganisms, resembling a rubbery pancake that converts tea into kombucha.
A two-stage process: Fermentation typically occurs in two stages. The first fermentation takes place at room temperature over several days or weeks. During this time, the SCOBY consumes the sugar in sweet tea and produces various organic acids, including acetic acid and lactic acid, carbon dioxide, and trace amounts of alcohol.
Key characteristics: This primary fermentation yields a tart, slightly sweet, and bubbly beverage with a host of beneficial microorganisms, or the probiotics you often hear about.
Second fermentation: The second fermentation often involves bottling the kombucha with added fruits or flavours. During this stage, kombucha undergoes further carbonation, which enhances its effervescence and taste complexity. Kombucha is then refrigerated to slow down the fermentation, preserving the desired level of carbonation and flavour profile and making it ready to enjoy.

Learn why skipping fermented foods is not in your best interest. The Good Bug reveals the power of fermentation through detailed case studies in the video below.

If you have a solid grip on what makes kombucha tick, it’s time to understand why keeping it cool is crucial!

Why does refrigeration matter for kombucha?

Once the initial fermentation process is complete, kombucha is almost always refrigerated. This step isn't just about serving it cold for a refreshing experience; it plays a crucial role in preserving its intended flavour and preventing it from becoming overly fermented.

Impact of no refrigeration: At room temperature, the live cultures within the kombucha become more active. While this activity is essential for the initial fermentation, it leads to overfermentation if left unchecked. This means that the microbes continue to consume the remaining sugars and produce more acids and carbon dioxide. It results in an overly carbonated kombucha with a sharply tart, almost vinegary taste that might not be palatable.
The power of the cold: Cold temperatures significantly slow down these fermentation activities. When stored in the refrigerator, the yeast and bacteria in kombucha enter a state of dormancy, drastically reducing the fermentation rate. This helps maintain the drink's intended flavour profile and carbonation levels, preserving its palatable balance between sweetness and acidity for longer.
Slow fermentation: Even when refrigerated, kombucha will continue to ferment, but at a much slower pace. This means that over time, you might still notice a slight increase in tartness or carbonation, but it will be a gradual change rather than a rapid one. Refrigeration puts the brakes on the fermentation process, allowing you to enjoy your kombucha within a reasonable timeframe at its intended flavour profile.

Components in kombucha	How do they change when kombucha is left out?
Sugar	Decreases
Alcohol	Increases
Calories	Decreases
Carbonation	Increases
Taste	Worsens

Curious about how long you can keep kombucha? Let's explore its shelf life next!

How long does kombucha last?

If you have a bottle of kombucha, you might wonder if leaving it at room temperature can cause it to go bad. Kombucha's high acidic content makes it a self-preserving drink, so pathogens are highly unlikely to inhibit, survive, or contaminate it. However, you can notice slight differences in taste and fizz if you do not follow proper storage guidelines.

The lifespan of your kombucha depends on whether it's homemade or commercially produced and how it's stored. Let's break down the typical timeline you can expect:

Homemade kombucha: When properly stored in the refrigerator, homemade kombucha can generally last for up to 3 months. However, for the best flavour and fizz, it's typically recommended to consume it within 1 to 2 months of brewing. The longer it sits, the more tart it will become due to continued fermentation.
Commercially bottled unopened kombucha: These bottles will have a ‘best-by’ date printed on them that usually spans 6-8 months when stored in the refrigerator. If left unrefrigerated, its quality will degrade much faster, and it's generally best consumed within about 1 week to avoid significant changes in flavour and carbonation.
Commercially bottled opened kombucha: Once you've popped the cap, the clock starts ticking faster. Even when stored in the refrigerator with a resealable cap, opened kombucha is usually best enjoyed within 1 to 2 weeks. After this time, you might notice a significant loss of fizz and a more pronounced tartness. If left unrefrigerated after opening, it's best consumed within about 1 week, but keep a close eye on any signs of spoilage.

You’ve sorted out how long kombucha can stick around, so let’s tackle how to tell if it’s overstayed its welcome.

How can you tell if kombucha has gone bad?

It's always a good practice to check the 'best-by' dates on the kombucha label. However, these are often just guidelines for peak flavour and quality rather than a strict expiration date indicating spoilage. So, how do you determine if your kombucha is still safe to drink? Here are some signs to consider:

Mould: This is the most definitive sign that your kombucha has gone bad and should be discarded immediately. Look for any fuzzy growths, typically on the surface of the liquid. Mould can come in various colours, including green, black, or white. If you spot any mould, do not attempt to drink the kombucha.
Overly vinegary taste: Kombucha is naturally tart, which will intensify over time due to continued fermentation. However, if the taste has become overwhelmingly vinegary, to the point where it's unpleasant and harsh, it's likely past its prime. While not necessarily harmful, the flavour may be unappetising. You can use this over-fermented kombucha as a vinegar substitute in salad dressings or cleaning solutions.
Unpleasant smell: A healthy kombucha has a slightly sweet and tangy aroma. If you detect any off-putting or rotten odours, something is likely amiss, and it's best to err on the side of caution and discard the bottle.
Lack of fizz: Kombucha is known for its natural carbonation. A significant loss of fizz doesn't automatically mean it's gone bad. Still, it can indicate that the fermentation process has slowed down considerably or that the seal on the bottle wasn't airtight. It might still be safe to drink, but the texture and overall experience will be different.
Excessive bubbling/pressure: While some fizz is good, a bottle that seems under extreme pressure or produces excessive bubbling upon opening could be a sign of over-fermentation that has gone too far, potentially leading to an imbalanced and unpleasant brew.

Now that you know how to spot the warning signs, let’s see how you can store your fizzy friend to keep it in great shape!

How to store kombucha for best results?

Proper storage is essential for maintaining the delicious tang and refreshing fizz of your kombucha and preventing it from becoming overly acidic. Treat your booch right, and it will reward you with its goodness. Here are some best practices to follow:

Refrigerate promptly: Once you bring your kombucha home (or after your homemade brew has reached the desired level of fermentation), store it in the refrigerator at a temperature between 34°F to 40°F (1°C to 4°C). The cold temperature significantly slows down the fermentation process, helping preserve its sweetness, flavour, and carbonation.
Avoid heat sources: Keep your kombucha away from heat sources such as direct sunlight, ovens, or warm rooms. Heat accelerates the activity of the live cultures, leading to faster fermentation and potentially a less palatable, more vinegary brew.
Limit air exposure: Once you've opened a bottle of kombucha, ensure you reseal it tightly if you're not finishing it in one go. Excessive air exposure can not only flatten the carbonation but also potentially introduce unwanted microorganisms.
Skip the freezer: While you might be tempted to freeze kombucha for longer storage, it's generally not recommended. Freezing can alter the texture and potentially harm the live cultures, impacting the overall quality of your brew once it is thawed.
Burping (for homemade brews): If you're brewing your kombucha, especially during the secondary fermentation (when you might add fruits or flavours), you might need to ‘burp’ the bottles periodically. Carefully and briefly open the bottles to release excess carbon dioxide buildup, preventing potential explosions. This is less of a concern for commercially bottled kombucha, which is typically packaged to handle the carbonation.

So, the next time you find a forgotten bottle of kombucha, don't immediately assume the worst! The fermentation process continues quietly over time, subtly altering the flavours and potentially developing a more nuanced taste profile, much like a fine wine. While the taste may shift, it doesn't mean your kombucha has gone bad.

Unlike perishable foods that spoil rapidly, kombucha remains safe for several months beyond the best-by date printed on its bottle, especially when refrigerated. Before you discard kombucha, give it a good look and a cautious sniff. If there's no mould and the aroma isn't offensive, take a small sip. Your taste buds are often the best judge! A more tart flavour is normal, but if it's overwhelmingly unpleasant, it might be time to let it go.

Are you ready to enjoy some perfectly brewed and cared-for kombucha? The Good Bug offers intriguing flavours like Apple Cinnamon, Strawberry Ginger, and Pineapple Basil. Visit our website to explore our collection of fermented drinks and take a delightful sip for your health and well-being!