How to Tell If You Have a Healthy SCOBY

How do You Know if Your Kombucha SCOBY is Healthy or Not?

How to Tell If You Have a Healthy SCOBY

Of all the things that couples argue about, I’ll bet the last one you’d ever think of is whether or not you have a healthy SCOBY in your kombucha jug. Yet that’s exactly what my husband and I were debating not too long ago after my first attempt at learning how to make kombucha from a healthy SCOBY given to me by a dear friend. I carried that little jar home from yoga class, excited by the idea of all the kombucha I could make and the flavors I could use … and then I forgot the poor little thing in my car. Overnight. In November. In upstate New York.

When we removed the SCOBY from the little jar, we saw some brown and black streaks on it. “Look at this,” my husband said. He assumed that those brown and black streaks meant we had a moldy SCOBY. I thought that those colors were normal, and probably just leftover from the last brew my friend had made. My husband was ready to call it quits even before we started, but I insisted on making up a brew of sweet tea. After we brought the SCOBY back to room temperature and let the sweet tea cool, we poured it all into a half gallon jar and covered it. Then we set it aside in a warm, darkish place and said a prayer. (Well, I said a prayer, anyway.)

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The next couple of days, my husband was not encouraged. After 20 years of brewing his own beer and wine, and plenty of experience in using other food preservation fermentation techniques, he noted that there were still no bubbles rising to the top of the fermentation vessel. “It’s probably not a healthy SCOBY,” he said. “We should just dump it and get another one from somewhere else.”

But I insisted that the lack of bubbles after a few days didn’t mean anything. Brewing kombucha isn’t anything like brewing beer, I told him. I kept the SCOBY warm and covered, and just watched. And waited.

Then … about 2 weeks later, my son and I were cleaning up the house and my husband asked if we were going to get rid of that jar of “failed” kombucha. I picked up the jar and looked inside, and to my surprise — there was a baby SCOBY floating on top! Turns out, I did have a healthy SCOBY and it was so healthy that not only had it fermented that half-gallon of green tea, it made a baby SCOBY so that I could start a second batch of kombucha. Success! I was elated.

So, the question I hear now from lots of people who want to make their own kombucha is, how do I know if I have a healthy SCOBY? Turns out, a SCOBY is really, really hard to kill. Outside of mold and deep freezing, there really aren’t too many ways you can kill a SCOBY.

Signs of a Healthy SCOBY

So, how do you know if your SCOBY is healthy before you start a new batch of kombucha? For the new brewer, this can be confusing. Learning how to tell if a SCOBY is healthy or not is a whole new set of skills.

What Color Should a SCOBY be? A healthy SCOBY is always white or light tan, or some shade in between. A darker brown SCOBY might just mean that the SCOBY is older, and probably won’t work to brew kombucha. A SCOBY can have streaks of brown or black on it – this is just leftover remnants of tea from the last brew. You can tell if a SCOBY is moldy by the presence of mold. And mold does NOT look like leftover tea bits. A moldy SCOBY has white or gray fuzzy growths on it. You’ll know what it is just by touching it. If, for whatever reason, your SCOBY has turned moldy, pitch it and start with a new SCOBY.

How Should My SCOBY be? A healthy SCOBY mat is about ¼ to ½ inch thick. It might float at the top of the brewing vessel. It might sink to the bottom. It might slide off to one side at an angle. It might even float right in the middle of the brewing vessel. It doesn’t really matter where your SCOBY decides to hang out, as long as it’s not moldy and otherwise looks healthy. You can also check the health of your SCOBY by giving it a little pinch between your thumb and first finger — if you can tear it apart with a pinch, then it most likely won’t give you a very good brew.

How Strong Was the Starter Liquid? If you really want to get into it, check the pH of your starter liquid. A pH of 3.5 or lower is best for preventing mold and creating an inhospitable environment for potentially harmful bacteria in your kombucha brew.


Does a SCOBY Make a New SCOBY? A healthy SCOBY will always make a new baby SCOBY when you set it out to brew. Yeast strands fall off the SCOBY and float to the bottom (or float up to the top, if your SCOBY has taken a deep dive to the bottom of the fermentation vessel) and create a new yummy biological mat. No matter where the original SCOBY is hanging out in the brewing vessel, the new baby SCOBY will float to the top. Even if the original and baby SCOBY are attached at the time you decant and pour off the kombucha, you should be able to easily remove the two.

Healthy SCOBY Tips:

  1. Don’t let your SCOBY get dehydrated. Always keep any unused SCOBYs in at least two cups of good, strong starter liquid. If the SCOBY gets dried out, it might start to grow mold at worst, or at best, is ineffective for brewing. (But these dehydrated SCOBYs make great dog chew toys.)
  2. Don’t refrigerate or freeze the SCOBY. When you chill the SCOBY for more than a few days, it will kill off all the healthy bacteria and yeast needed to brew kombucha. At best, you can expect a moldy brew with a formerly frozen SCOBY.
  3. Don’t skimp on size. Yes, size does matter when it comes to your SCOBY. A tiny little thumb-sized piece of SCOBY isn’t going to do much in a half gallon brewing vessel. When you start a new batch of kombucha, the bigger the SCOBY, the better. You can’t really ferment with an itty bitty SCOBY, and at best, you’ll end up with some kind of vinegar that doesn’t have all the great kombucha benefits you’re after.

And if you’re wondering … that first batch of kombucha that I brewed from my “unhealthy” SCOBY turned out delicious. I flavored it with some fresh ginger and organic peach jam. I even had enough to share with a friend!

What are your experiences in keeping your SCOBY healthy? When you’re given a new SCOBY, what do you look for? Leave a comment here and share your tips and recommendations with us!

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