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The kombucha SCOBY is an incredibly hardy microorganism, where mold growth is actually rare. But if you do experience mold, it will develop on the top of your brew, where it's exposed to oxygen. If you do experience mold, you MUST DISCARD EVERYTHING and start with a new SCOBY and starter liquid from your SCOBY HOTEL, or purchase a new SCOBY from us!

Remember, mold on kombucha looks like mold on any other food. It's colorful, fuzzy and spreads quickly. Brown, stringy, or clumpy yeast sediment in your brew and attached to your SCOBY is a normal part of a healthy brew. While unusual looking, kombucha yeast looks very different than mold. When in doubt, email us a photo of your brew at

Two side by side photos of the top of a kombucha brew. The one on the left shows fuzzy white and bluish-green mold spots. The one on the left shows a brown yeast blob with some bubbling around it.


1. Too little starter liquid aka mature kombucha (2 cups per gallon)

The starter liquid is the mature kombucha tea from your previous batch. This is one of the most important ingredients in your kombucha brew. This liquid helps to acidify and jumpstart the fermentation of new sweet tea. Don't skimp! Use about 2 cups for every gallon of new sweet tea!

2. Too cold temperature (below 62)

If your ambient room temperature in your home is consistently in the low 60's, your kombucha will ferment too slow, and as a result, not acidify fast enough making it susceptible to mold. Move your kombucha to a warmer spot or consider a Fermentation Heater Belt to use in colder months.

3. Using a refrigerated SCOBY

SCOBYs and their starter liquid should always be stored at room temperature. Be sure to follow our guidance on SCOBY Hotels and/or Taking a Break from Brewing. Refrigeration will cause the yeast and bacteria to go dormant. Post-refrigeration, your kombucha will likely ferment too slow due to the dormant microbiota, and as a result, not acidify fast enough making it susceptible to mold.

4. Using the wrong base brew ingredients

We always emphasize using real tea (camelia sinensis) and real cane sugar when brewing kombucha. These are the traditional, centuries-old ingredients that the SCOBY culture has developed alongside. Substituting other non-tea botanicals or other sugar types in this initial brewing stage may result in mold. If you are an experienced brewer, and you choose to experiment with non-traditional ingredients in the initial fermentation, use a SCOBY from your SCOBY Hotel just in case!

Note: You can always flavor your kombucha with non-traditional ingredients during the secondary "flavoring" stage prior to bottling.


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