Moldy Kombucha, Again?? Never have mold with this one simple trick...
- Hannah Harris
- Jul 29, 2025
- 7 min read
Updated: Dec 31, 2025
Making your own kombucha can truly be a delightful experience. However, many home brewers keep having mold in their batches. If you've encountered a moldy kombucha culture, you're certainly not alone. But don't worry! I'm here to share some valuable tips to keep your kombucha mold-free. Plus, I'll reveal a clever trick I used to never have mold again.
Let’s explore how you can save your brew and enjoy the refreshing tang of kombucha without unwanted guests!
First, let's cover basic Kombucha Culture health...
1. Pick the Right Size of Glass Container for your Kombucha needs
Do you drink a lot of kombucha or just a little? Picking the correct size container for your SCOBY Hotel and Brewing Station will ensure that you have an adequate amount of strong starter liquid for your brewing and enough room for the fermentation. I could drink Kombucha all day, every day (about a full glass bottle or two of GT's from the store, to give a better reference.) So, I chose to have a 2 gallon glass drink dispenser for my Brewing Station and a 2 Gallon Glass Anchor Container for my SCOBY hotel. To be honest, when I get back into regular brewing, I think I may double my brewing space for two brews at the same time - I just love Kombucha.
If drinking Kombucha is more of an occasional thing, I'd say you would be perfectly safe keeping a 1 liter Brewing Station and a Quart Jar for your SCOBY Hotel. The Key is having adequate headspace for proper aeration, starting with a clean jar, and a strong starter.
To Recap, If you could drink a bottle or two a day, go with 2 gallon glass containers for your SCOBY Hotel and Brewing Station.
If just an occasional Kombucha drinker, go for either 1 gallon Brew Station and SCOBY Hotel OR 1 Liter Brew and 1 Quart SCOBY Hotel.
2. Keep it Clean
Maintaining a clean brewing area and using sanitized equipment is vital in preventing mold. Before you start a new batch, wash all jars, utensils, tea towels/cloth used to cover your cultures and surfaces thoroughly.
I prefer washing everything with hot, soapy water, followed by a vinegar rinse and finally a regular rinse. I live in a very humid, mold prone area so you can trust me when I say I've had my share of moldy batches! No matter how hard I tried, I kept having mold in my batches. That is, until I followed the steps on this article.
You can make your own vinegar rinse (also known as an "Acid Rinse") by using a mixture of water and vinegar; about a 1/4c vinegar to 1 Gallon of water - the typical capacity of most sinks.
3. Monitor Temperature
Kombucha likes a nice, "Baby Bear" type climate - not too hot, not too cold, just right. The temperature at which you brew your kombucha plays a significant role in the fermentation process. If your brew becomes too warm—over 80°F (27°C)—you create an environment that's perfect for mold. Studies show that at higher temperatures, the likelihood of mold increases by as much as 30%. If your kitchen tends to get warm, seek a cooler spot or use a fermentation wrap to maintain an optimal temperature. (In my personal experience, I've had my batch reach up to 80°F and be totally fine. However, do NOT use any starter that you see mold spores in.)
Try to brew your kombucha in a stable environment with a temperature between 68°F to 78°F (20°C to 26°C).
One of the easiest ways to monitor temperature is by purchasing a thermometer strip. I was blessed with two by my mother but you can find everything Kombucha related at my favorite online Kombucha store - KombchaKamp.com (non-affiliated.) Using a thermometer strip allows you to easily peak at the temperature of your brew and go on without making a mess or having to clean a thermometer every time you check.
4. Use a Secure Cloth Cover - Not Cheesecloth!
If you're like me, you try to make do with what you have and not buy anything you don't need to. I made the mistake of using Cheesecloth to cover my first batch of Kombucha and let's just say the gnats were absolutely touched by my hospitality. A securely-fitted cloth cover acts as a solid barrier against mold spores and especially gnats and flies. I recommend using a breathable material, like a clean tea towel or a coffee filter. If you're making smaller batches or have a small-mouth opening, the coffee filter with a rubber band should work fine - although I would recommend doubling up on the filter.
This allows for airflow while keeping out unwanted contaminants. Ensure that the cloth is tightly secured around the jar with a rubber band, keeping your brew protected from potential issues.
5. Regularly Check for Signs of Mold and Overall Health of your SCOBYs
It’s essential to monitor your kombucha regularly. Check daily in the early stages of your SCOBY culture for any signs of unusual changes, it may be mold.
If you have an older SCOBY and it looks a little flat or lackluster -especially if the fluids in your batch are low - you may need to feed it! Yes, just like sourdough you need to feed your Kombucha SCOBY Hotel. All this requires is a bit of sugar, water, and tea! Simply make a large batch of tea adequate to the capacity of your SCOBY Hotel, let it reach room temperature - tea that is above 75°F may harm (or even kill) your culture, and pour it in! Don't be afraid to throw some citrus in there as well to simultaneously lower the pH and give sugar to your batch - just make sure the peels are off!
Below is just a sample of documented moldy cultures taken by KombuchaKamp.com They offer a full library of documented molds and more for only 7.99/month.
KombuchaKamp.com owns all rights to these images.
As a rule of thumb, Look for fuzzy spots, powdery looking substances, or discoloration. If you see any signs of mold, it’s best to discard the entire batch right away. Statistically, consuming contaminated kombucha can lead to food poisoning in about 5% of cases, so it's better to be safe than sorry!
Remember: Fuzzy, powdery, off-colored. A healthy culture ought to look like the first picture in the article. A healthy, shiny disk with multiple layers, amber in color and a nice glistening sheen - it will also feel slimy to the touch, something you may have to get over or get help with if you're sensitive to textures.
6. Use Quality Ingredients
The ingredients you choose directly affect your kombucha's health. Always select high-quality teas and sugars.
Organic black or green tea is ideal, as it provides the necessary nutrients for your SCOBY (Symbiotic Culture Of Bacteria and Yeast). In fact, high-quality tea enhances fermentation success rates by up to 50%. If your tea is old or not well-stored, you may struggle with fermentation, increasing the risk of mold.
I had the best success with Organic ingredients. Fresh is also important, you don't want to use fruit that have invisible mold spores on them. A good way to prevent mold spores from fruit (even the freshest of fruit), simply give it an "Acid Wash" as described in the "Keep It Clean" section of this article
7. Avoid Over-oxygenating your Brewing Station
While your kombucha culture does need some oxygen to thrive, it’s crucial to avoid over-oxygenating. Excessive stirring once fermentation starts in your Brewing Station can introduce too much air, increasing the chance of mold growth. It also, interrupts the fermentation process if you stir too frequently.
Simply stir till combined and let her go! Checking the temperature and health periodically, watching out for signs of mold. Hopefully if you do everything on this list, you won't have to waste your efforts on a batch that turns moldy - it truly is tragic.
As for your SCOBY Hotel, Covering your Kombucha Culture with a Tea Towel is one of the best ways to have adequate air flow and keep any gnats or flies out!
Good things come to those who wait, Kombucha is no exception. Let your kombucha ferment without any interference and you'll be well on your way to a Kombucha brew that rivals store bought.
Ready for the Secret to Mold-Free Kombucha?
8. What I did - Use Organic Apple Cider Vinegar
One of the easiest and efficacious ways to combat potential mold is by adding a splash of apple cider vinegar to your kombucha.
This simple addition helps lower the pH of your kombucha, creating an environment that is less welcoming to mold spores. Adding about 1 to 2 tablespoons of apple cider vinegar to your batch can be a game-changer. Research shows that a pH level below 3.5 is generally effective in preventing mold growth.
Ever since I've done this (little over a year ago) I've never had trouble with mold. It may be a little unorthodox, but it works! It's something I will keep doing to ensure I don't waste my time. money, and hard work just to see it (literally) go down the drain... or more accurately, in the creek.
Brewing kombucha is an amazing experience, one that makes you feel like you can make anything but it takes some attention to detail (and a little help from Ol' ACV) to keep mold at bay.
By incorporating apple cider vinegar, maintaining cleanliness, monitoring temperatures, and using quality ingredients, you can enjoy the brewing process without worry.
Remember these tips for your next round of brewing, and hopefully you’ll see a Kombucha culture that thrives for years to come!
Cheers to brewing a sturdier kombucha – here's to your next batch being deliciously mold-free!
Works Cited:
Anderson, Christopher. “Is That Mold on My Kombucha? The Ultimate Guide to Safe Brewing.” Kombucha Kamp, 8 May 2025, www.kombuchakamp.com/is-that-mold-on-my-kombucha-the-ultimate-guide-to-safe-brewing.
Disclaimer: I'm not a doctor and if you have any concerns, you need to discuss them with a trusted physician. Do not hesitate to go to the hospital if you feel it's necessary. I am not giving medical advice, speak with your doctor first before trying any new foods or routines that are food related. This content is for informational purposes only and not a substitute for professional medical advice, diagnosis, or treatment. Users are advised to always seek the advice of their physician or other qualified health care provider with any questions they may have regarding a medical condition or treatment. The website or platform is not liable for any risks or issues associated with using or acting upon the information provided. Using the website does not establish a doctor-patient relationship. In case of a medical emergency, users are advised to call their doctor or 911 immediately.
Comments