Primary Fermentation FAQ

​My kombucha got too sour! What should I do?

No worries - your kombucha has simply over-fermented and turned into kombucha vinegar. While it might be too tart to sip straight, it’s far from a lost cause.
Here’s how you can use it:

• Starter liquid for your next batch: Overly sour kombucha is perfect for lowering the pH quickly and protecting your next brew from mold.
  
• ​Salad dressings and marinades: Use it like you would apple cider vinegar—for vinaigrettes, sauces, or even a tangy splash in soups.

To prevent this in the future, try shortening your brew time, especially in warmer weather when fermentation speeds up. Taste your kombucha starting around day 5 to catch it before it gets too strong.

My house is really cold. How do I keep my kombucha warm enough to ferment properly

Kombucha ferments best between 68°F and 78°F. If your home is cooler than that, fermentation can slow down significant or even stop leading to weak brews or mold risk. Here are some simple ways to keep your kombucha warm:
1. Move it to a warmer spot in your home:

• Place your jar on a high shelf, top of the fridge, or inside a cupboard—warm air rises, so higher locations tend to stay cozier.
• Avoid drafty windows or areas near exterior walls.

2. Insulate from cold surfaces:

• Put a folded towel, book, or cork trivet underneath your jar to insulate it from a cold counter or shelf.

3. Use a kombucha heating wrap or seedling mat:

• These plug-in warming devices gently raise the temperature around your jar. Look for one with a thermostat or automatic shut-off for safety.

Always check the temperature with a thermometer if you're unsure - keeping your brew within the ideal range will give you the best flavor and fizz.

What is the importance of temperature in brewing kombucha?

Temperature plays a key role in how your kombucha ferments. The ideal range is 68°F to 78°F. Within this range, you get the best balance between yeast and bacteria, resulting in a brew that’s flavorful, fizzy, and not overly sour or flat.
Here’s how temperature affects your brew:

• Too cold (below 68°F): Fermentation slows down. The yeast and bacteria become sluggish, which can lead to weak kombucha or even mold growth if the brew doesn’t acidify fast enough.
• Too warm (above 78°F): Fermentation speeds up. Yeast becomes more active than bacteria, leading to overly sour, overly yeasty kombucha that can develop too much alcohol or vinegar-like flavor.

Maintaining a steady, moderate temperature gives you the most consistent and delicious results.

What is the pH of kombucha?

Kombucha is an acidic beverage, and its pH is typically between 2.5 and 3.5 once fully fermented. This acidic environment is key to its safety and success.
To understand pH:

• A pH of 7 is neutral (like pure water).
• A pH below 7 is acidic.
• A pH above 7 is basic (or alkaline).
  
  

The low pH of kombucha helps prevent the growth of harmful microorganisms, making it a naturally self-preserving drink. Maintaining a proper pH ensures your brew is both safe and effective—especially during the early stages of fermentation when the SCOBY is still establishing itself.

While it’s not required, you can use pH test strips or a digital pH meter to monitor your kombucha, especially if you’re new to brewing or want more control over the flavor and safety of your batches.

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