Been brewing kombucha for years and I've made every mistake in the book. Here are the 5 that ruin most people's first batch:

1. Using tap water with chlorine. Chlorine kills the bacteria in your SCOBY. Use filtered or spring water, or let tap water sit out for 24 hours.

2. Brewing tea too hot and adding the SCOBY. Your SCOBY is alive. Anything above 85°F (29°C) can damage it. Always cool your sweet tea to room temperature first.

3. Not enough starter liquid. That sour liquid from your previous batch (or the liquid your SCOBY came in) is what drops the pH and protects against mold. Use at least 1-2 cups per gallon.

4. Moving or disturbing the jar during F1. Every time you jostle it, the new SCOBY forming on top breaks apart. Find a warm spot and leave it alone for 7-14 days.

5. Sealing the jar during first fermentation. Your SCOBY needs oxygen. Cover with a cloth or coffee filter secured with a rubber band — never a sealed lid during F1.

If you want the full step-by-step breakdown (SCOBY care, second fermentation for carbonation, flavoring techniques, and more), I put together a complete beginner course inside The Kombucha Lab.