Why Is My Kombucha Not Fizzy Causes And Easy Fixes

Kombucha’s signature tangy fizz is what many home brewers aim for—yet achieving consistent carbonation can be frustratingly elusive. You’ve nurtured your SCOBY, waited patiently through fermentation, only to open the bottle with a disappointing *pfft* instead of a satisfying *pop*. If your kombucha isn’t fizzy, you're not alone. Carbonation issues are among the most common challenges in home brewing. The good news? Most problems have simple explanations and even simpler solutions.

Carbonation in kombucha happens during a secondary fermentation phase when yeast consumes sugar and produces carbon dioxide (CO₂). If that process stalls or underperforms, your drink stays flat. Understanding the science behind fizz—and the conditions it needs—can transform inconsistent batches into reliably bubbly success.

Understanding Kombucha Carbonation: How Fizz Happens

Carbonation in kombucha is a natural byproduct of fermentation. During the first (primary) fermentation, bacteria and yeast in the SCOBY break down sweet tea into organic acids, trace alcohol, and CO₂. However, because the vessel is typically open or loosely covered, most of that gas escapes into the air. That’s why primary fermentation rarely results in a fizzy drink.

The real magic happens in the second fermentation. When kombucha is bottled in sealed containers with added sugars—like fruit juice, dried fruit, or a pinch of cane sugar—the yeast continues fermenting. This time, the CO₂ has nowhere to go, so it dissolves into the liquid, creating carbonation. The balance between yeast activity, sugar availability, temperature, and sealing integrity determines how much fizz develops.

“Proper secondary fermentation is where kombucha goes from flat to fantastic. It’s all about giving the yeast the right fuel and environment.” — Dr. Lena Patel, Fermentation Scientist at Oregon State University

When any part of this equation is off, fizz suffers. Let’s explore the most common culprits and how to fix them.

Top 5 Reasons Your Kombucha Isn’t Fizzy (And How to Fix Them)

1. Insufficient Sugar in Secondary Fermentation

Sugar isn’t just for sweetness—it’s the engine of carbonation. Yeast needs fermentable sugars to produce CO₂. If you don’t add enough sugar during bottling, there won’t be enough fuel for gas production.

Tip: Add 1–2 teaspoons of sugar per 16-oz bottle. Fruit juice works well too—½ oz per bottle adds flavor and fermentables.

Using non-fermentable sweeteners like stevia or monk fruit won’t help. Stick to cane sugar, honey (in moderation), maple syrup, or fruit-based sweeteners. Avoid artificial sweeteners entirely during secondary fermentation.

2. Poor Sealing of Bottles

No matter how active your yeast is, if your bottles aren’t airtight, CO₂ will escape. Flip-top bottles (Grolsch-style) or high-quality swing-top jars with intact rubber gaskets are ideal. Plastic soda bottles can also work—if they firm up during fermentation, you’re on the right track.

If you’re using mason jars with standard lids, they often don’t seal tightly enough for proper carbonation. Invest in proper fermentation bottles designed to withstand pressure.

Bottle Type	Seal Quality	Best For Fizz?
Swing-top (Grolsch)	Excellent	Yes – top choice
Plastic soda bottles	Good (check firmness)	Yes – great for testing
Mason jar with metal lid	Poor	No – leaks CO₂
Glass bottles with plastic caps	Fair	Maybe – inspect seals

3. Inactive or Imbalanced SCOBY

Your SCOBY (Symbiotic Culture of Bacteria and Yeast) must contain both healthy bacteria and sufficient yeast to carbonate properly. Over time, especially after multiple batches, the yeast population can decline—especially if you’re removing too much yeast sediment (the “baby” SCOBY or brown strings) each time.

A weak yeast presence means less CO₂ production. Signs of an underperforming SCOBY include slow fermentation, lack of vinegar-like tang, and consistently flat brews.

Tip: Save some of the unfiltered kombucha from a successful batch as starter liquid—it contains active yeast and helps jumpstart carbonation.

4. Temperature Too Low

Yeast is temperature-sensitive. Below 68°F (20°C), its activity slows dramatically. If your brewing space is chilly—like a basement in winter or a shaded kitchen corner—your secondary fermentation may be too sluggish to build pressure.

For optimal fizz, keep bottled kombucha at 72–78°F (22–26°C) for 2–5 days. Warmer temperatures speed up fermentation but increase the risk of over-carbonation or exploding bottles, so monitor closely.

5. Releasing Pressure Without Realizing It

“Burping” bottles—briefly opening them to release excess pressure—is sometimes recommended to prevent explosions. But doing it too early or too often can let out all the CO₂ before it dissolves into the drink.

Wait at least 3 days before checking pressure. Gently press the cap: if it’s hard and domed, you’ve got carbonation building. Only burp if the bottle feels rock-hard, and do it over a sink.

Step-by-Step Guide to Fix Flat Kombucha

If your latest batch fell flat, don’t toss it. You can often revive it with a second chance at fermentation. Follow this timeline to rescue and re-carbonate:

1. Day 1: Transfer flat kombucha into clean, airtight bottles. Add 1–2 tsp of sugar or ½ oz fruit juice per 16 oz bottle.
2. Day 2–5: Store bottles at 72–78°F (22–26°C). Avoid direct sunlight.
3. Day 3: Check one bottle by gently pressing the cap. If firm, refrigerate immediately. If soft, wait another day.
4. Day 4–5: If still flat, repeat the process: add fresh sugar, reseal, and warm-ferment again.
5. Final Step: Once fizzy, refrigerate all bottles to halt fermentation and preserve carbonation.

This method often rescues under-carbonated batches within 3–5 days. Patience is key—rushing leads to disappointment or dangerous over-pressurization.

Checklist: Ensure Fizzy Kombucha Every Time

• ✅ Add 1–2 tsp sugar or fruit per 16 oz bottle before sealing
• ✅ Use airtight, fermentation-safe bottles (swing-tops preferred)
• ✅ Ferment secondary bottles at 72–78°F (22–26°C)
• ✅ Wait at least 3 days before checking carbonation
• ✅ Refrigerate promptly once desired fizz is reached
• ✅ Retain some yeast-rich liquid from previous batch as starter
• ✅ Avoid over-cleaning SCOBY—some brown strands are normal and helpful

Real Example: Sarah’s Flat Batch Turnaround

Sarah had been brewing kombucha for three months with mixed results. Her first two batches were mildly tart but completely flat. She used mason jars with regular lids and skipped adding extra sugar during bottling, assuming the original sugar would be enough.

After reading about secondary fermentation, she switched to swing-top bottles, added 1 tsp of cane sugar per bottle, and moved her bottles to a warmer cupboard near the oven. On day 4, she felt pressure building. She refrigerated the batch, chilled a bottle, and opened it carefully. This time, it hissed open with a crisp, bubbly pour. She now shares her “fix-it” method with her local fermentation group.

Sarah’s story highlights how small adjustments—especially sealing and sugar—can make a dramatic difference.

Common Mistakes That Kill Carbonation

Even experienced brewers make errors that sabotage fizz. Watch out for these pitfalls:

• Over-refrigerating too soon: Cooling kombucha before secondary fermentation completes halts yeast activity prematurely.
• Using old or dead starter tea: Starter liquid should be acidic and alive with culture. Using store-bought kombucha that’s pasteurized won’t help.
• Over-flavoring with citrus: While lemon or lime add zest, their acidity can inhibit yeast. Use sparingly—no more than a few slices per gallon.
• Shaking bottles during fermentation: Agitation releases CO₂ and reduces fizz. Handle bottles gently.
• Storing in cold environments: Garages, basements, or fridges during fermentation stop carbonation in its tracks.

Frequently Asked Questions

Can I carbonate kombucha without adding more sugar?

Technically yes, if enough residual sugar remains from the primary ferment. But results are inconsistent. Adding a small amount of fresh sugar gives yeast the boost they need for reliable fizz.

Why did my kombucha explode in the fridge?

This usually means fermentation didn’t stop when you thought it did. Either the bottles weren’t cold enough, or there was too much sugar and active yeast. Always refrigerate promptly after reaching desired carbonation and use caution when opening.

How long does secondary fermentation take?

Typically 2–7 days, depending on temperature and sugar content. Warmer = faster. Check daily after day 2. Once fizzy, refrigerate immediately to stabilize.

Expert Tips for Consistent Bubbles

To maintain fizz across batches, treat your kombucha like a living ecosystem. Stability and consistency yield the best results.

Tip: Label your bottles with the date and sugar type used. Tracking variables helps you replicate success and avoid past mistakes.

Some brewers swear by “priming” bottles with a splash of actively fermenting kombucha from a current batch. This introduces fresh yeast directly. Others add a raisin or piece of ginger—one raisin per bottle provides natural yeast and nutrients without overpowering flavor.

“The secret to fizzy kombucha isn’t complexity—it’s consistency. Control your temperature, feed your yeast, and seal tightly.” — Marcus Reed, Home Brew Instructor and Founder of Cultured Living Workshop

Conclusion: Turn Flat into Fizzy

Lack of fizz doesn’t mean failure—it’s feedback. Your kombucha is telling you something about its environment, ingredients, or process. With a few targeted adjustments, nearly any flat batch can be rescued, and future ones made reliably bubbly.

Start by auditing your method: Are you adding sugar? Are your bottles truly airtight? Is your brewing space warm enough? Small changes lead to big improvements. Don’t give up after one flat batch. Instead, use it as a learning step toward mastering the art of homemade carbonation.

💬 Have a kombucha fizz breakthrough or tip? Share your experience in the comments and help fellow brewers bubble up their brews!