Fermentation Time

Hello Kombucha Friends…

I’ve been receiving many questions asking, “How long should I ferment my brew?”

This is an excellent question and the answer depends on you. First, let’s look at the factors that influence fermentation time for Kombucha.

  1. Temperature
  2. Taste
  3. Size & Shape of Vessel
  4. Acids expression

1. Temperature

The hotter the temperature, the faster the ferment. Conversely, the cooler the temperature, the slower the ferment. The ideal temperature for fermenting Kombucha is 70-80 degrees F. In the summer, my brew time is anywhere from 10-12 days, whereas in the winter it can be 2 weeks or longer. Sometimes I use a heating pad in the winter, but since it doesn’t get below freezing in Southern California, it’s not really necessary.

2. Taste

This is the deciding factor for most people. I recommend that after 7 days of fermenting, you take a straw and insert it under your SCOBY and take a sip. Is it too sweet? Too tart? Not tart enough? You are the ultimate decider in this process. What tastes delicious to you? And your taste will evolve over time the longer you brew Kombucha. I’ve also discovered that I am better able to sense when the Kombucha is ready based on how the weather has been, the date it was brewed, etc.

How to fix the flavor


There are a couple of things you can do to improve the taste of your Kombucha if it has been brewed too long.

*Add some less mature Kombucha to the more mature Kombucha to even out the flavor
*Dilute with water or juice
*Use it as vinegar (you can use really tart Kombucha the same way you use vinegar)

Once you found the flavor you like, stick it in the fridge. The drop in temperature will slow down the fermentation process.


Allow your Kombucha to continue to ferment. If after a couple of weeks your Kombucha is still too sweet, then your culture may have fallen dormant and you will need to revive it.

2ndary Fermentation

If you enjoy the 2ndary fermentation process, then you might not want your brew to be as tart since it will be fermenting a little longer – however, the addition of sugar (from the fruit or ginger,etc) will also add a little sweetness.

I keep a log book to record the date I brewed my batch, since I have multiple batches going at once, this keeps it easy to know which one will come to fruition next.

3. Size and Shape of Vessel

There is a bit of physics that goes into brewing Kombucha. Your culture will always grow to the size of the vessel – meaning that whatever size your SCOBY is, the new culture will always grow so that it completely seals off the aperture of the vessel.

I ferment in gallon sized pickle jars – they are more tall and less wide. Therefore the surface area covered by the SCOBY is less than the depth of my vessel. It will ferment more slowly since less surface area to depth is covered.


I also ferment in a gallon sized glass bowl with a really wide mouth. Therefore the surface area covered by the SCOBY is more than the depth of my vessel. It will ferment faster because there is more surface area to depth covered.

Short depth and more surface area in a Kombucha brewing vessel can decrease the fermentation time as demonstrated in this photo

4. Acids Expression

Based on previous research, it has been discovered that there are certain amino acids that aren’t expressed in the fermentation process until at least 30 days have passed. For most of us brewing a gallon batch, at 30 days, our brew would be undrinkable and taste like vinegar. This is why many people prefer to do a continuous brew – Check out the page about it here.

On the GT’s bottles you will see that his has been fermented for 30 days, and yet it is quite delicious. My theory has been that he brews it in vessels of such a size and volume that even after 30 days, the ferment is still potable. This is only a theory as he doesn’t allow visitors into his facility.

In the end, it really is up to you in terms of how long to ferment your Kombucha. The more times you engage in the process, the more intuitive this will become.

Happy Brewing!

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Responses to Fermentation Time

  1. I have the problem of my booch being too sweet in spite of it brewing for over one month. I know you mentioned that the SCOBY might have gone dormant. How do I go about reviving the SCOBY?

  2. I’ve never heard anyone say what the ideal ph is to start the Kombucha brew and is it ok to use vinegar to achieve that ph. Thanks so much Jimmy

  3. Great info! Thanks so much. I think I had start to be suspicious about why my bowl brew was fermenting faster than my pickle jar brew and its the surface area!


  4. Hi Hannah,
    Thanks for sharing all your wonderful knowledge. Just wondering why all the Kombucha continuous brewing containers have the pouring spigot at the bottom rather than midway or near the top since so many people recommend to pour the KT off the top to drink or bottle. Your insight would be appreciated!

  5. I’ve looked all over for an answer to this, and am wondering if I’m the only one who’s run into this for some reason.

    I’ve had a continuous brew going for several months, and love it. The only problem I’ve ever had is that the spigot got clogged. So I planned a cleaning. I got another brewing vessel (the exact same kind I have been using), washed it thoroughly with hot water and vinegar, and (to shorten my description of the process) emptied my old one, cleaned that vessel the same way, then filled both vessels half way with scobies and KT, and added fresh sweet tea.

    After two days, I took a quick sample from both vessels. The old vessel’s contents are perfect (just needs another day or two). But the sample from the second vessel, I spit out. It has a VERY strong plastic taste to it that makes it completely undrinkable. Could that be some sort of contamination (it’s been only two days and doesn’t taste at all natural, so I doubt that)? Or could I have gotten a more-easily-leachable-for-some-reason spigot?

    Anyone ever run into this? Should I throw the whole thing out, or is there some way to fix the problem?

    • As you likely know Ben, plastics come in different grades. If the new spigot is of a lower grade plastic, it could be leaching into your booch. We recommend these spigots as they are made of plastic #5 which is the most corrosive resistant.

  6. Will adding my, store bought, scoby to the
    Sweet black tea mix when it is warm help
    “Kick start ” my process during cold winter

    • We do not recommend using store bought Kombucha to grow SCOBYs for the reasons listed here. Nor do we recommend mixing cultures from different sources in your main Kombucha brewing vessel in order to prevent competition. If you want to help your Kombucha in the winter – try using a heating source to maintain the optimum temp of 80 degrees.

  7. Hannah: How many calories do you suppose are in a finished cup of kombucha? Does the action of the yeast and bacteria change the calorie count when it eats the sugar? this is all so fascinating!

    • Hi Martha. It will vary depending on ingredients & brewing time. The longer the KT brews, the less sugar present and thus the lower calorie count. When you add your flavorings, you are often adding sugar which will raise the caloric value. An unflavored Kombucha with a long ferment can have as few as 30 calories per 8oz serving.

  8. Hello Hannah,

    I am on day 7, and using the crock for continous KT. I tasted this morning, still needs time, but could taste the spritze and tartness. Plan on flavoring and bottling, I noticed in pic you use Pellegrino bottles, I have been recycling now I will keep and with tops. Thanks a bunch, glad to enter the KT culture.


  9. Hey Mz. Hanna;
    I purchased and downloaded your continuous brewing guide, and thank you. Its great. I have a scoby now and will be attempting my first “batch o buch” soon.
    I know PH test strips are not really essential but being sort of anal I went to our small but local health food store and two pharmacies looking for PH test strips and the strips I can buy locally will only test to values as low as five acidity. They are the common litimus strips with a color guide that will indicate higher, more alkalyne values well into the alk. range but not in the acid range to a PH of three. or less. Where can I order the right PH test stuff K.Mama.
    I will fearlessly carry on the brewing with out them, but I sure would like some, juz becauze. Can you help?
    Dave in Montana

  10. Hi Hanna;
    My old roomie gave me his continous Brewing system. He’s off in Afganistan no doubt starved for kombucha. And has no idea where his instructional pack is. But to make a long story short. Ive got the crock the stand and tea. Iam going to purchase a scoby and have watched your brewing and flavoring vid’s. and Im preparing to brew, but I haven’t seen any info on the long term care of the system. (e.g.) like how often do you remove the daughters, or are daughters produced? How long do you use the same mother? How often Should the crock be thoughly cleaned? If you pointed me in the direction of any vid’s or instructions I can down load or buy it would bless my life a bunch.
    thanx a lot
    Dave in Montana

  11. The temp is what is slowing down your brewing. I'd recommend putting your brew atop the fridge to get it some warmth. The brown things are yeasties, they are good! The SCOBY itself doesn't grow to cover the surface area, but it creates a new layer that will cover the entire surface. Because of the cold, it may only be a thin skin. As the temp heats up, it will thicken.

  12. I got a scoby from a friend, and am worried because my scoby did not grow to cover the surface area of my brewing container. How can I tell if my scoby is dead? It is kinda cold in our house (about 60F – it is an older house with wooden windows). It has been ten days and it seems to be pretty much the same size, but the tea does taste fermented (although a bit on the sweet side). It is also pretty brown on the bottom and has a lot of those brown things hanging down from the bottom (like you show in your video, but mine is all over and yours only has a tiny amount). Thanks for the help, Paula

  13. I did not know that GT's was brewed for 30 days. I have never tried the stuff. Been making my own for almost 20 years. The 30 days might explain why his drinks are not 100% Kombucha. He may well use the 10% juice to sweeten it up after a 30 day brew. I am brewing in 3-12 gallon crocks now and the time is still the same, so the size of the brew doesn't seem to make a difference as to the time. Just my 2 cents.

  14. I'm so glad to find this blog. My first batch is in the pantry. Your video Kombucha Kamp was really helpful. Thank you so much!

  15. yeah, that GT….
    my theory has always been that he is counting his 2nd ferment (in the bottle) in his time line.
    I always let mine sit in the bottle for at least six weeks & bottle in beer bottles with the oxygen adsorbing caps..

  16. 1-
    Big thank! if depth is to high there will be a big difference between top and bottonm of tank. this is one of my preblems. top is ready but not bottom

    GT dave’s don’t want to wait 30 days to harverst kombucha!!! may be the first time, but what do you think about continuous brewing!!! mother can be more than 30 days …. and contains these acids and reproduce it in the new kombucha


  17. My first batch completed last week!
    I bottled my Kambucha with Blackberries (OMG! so good), but wished I had kept one bottle just plain, because the timing was perfect (for my tastebuds, of course)!
    I live in Alaska, the temp is averaging 65 these days with 18 hours of sunlight. My batch fermented for two weeks exactly.

    • Carrie – I live in ak and just starting making kombucha! Is about two weeks average for fermenting in AK? I made a batch and remembered Ieave Thursday for a week and 3 days for camping!! Was worried it would be to tart when I come back

  18. I say feel free to experiment with different fermentation times. It could be the crimper does a good job of sealing out oxygen and therefore slows fermentation.

    I’m not sure what method GT uses – he’s pretty private about that. But I imagine that he also brews his at a much larger scale than us home brewers.

    I let mine 2ndary ferment for 3-5 days, then move it to the fridge.

  19. Hi! I’ve started brewing my own kombucha again after a few months hiatus. Recently, met a fellow amateur brewer and she mentioned that she lets her 2nd ferment sit for a month, sometimes two. She also caps her bottles by using a crimper… like the ones used on beer bottles. Sampled a bit of this kombucha and it was delish! Wondering if this method is what GT uses?

  20. I’m so glad to have found a kombucha-centered blog! I’ve brewed my own before, but due to space issues I stopped a few months ago. However, I’m moving on May 31st, and at the new house I’ll have plenty of room to start up brewing again. Can’t wait!

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