The Quick Guide to Kombucha pH

This is your quick guide to kombucha pH, including how to track the acidity of your home brew, how to lower the pH, and why acidity matters!

Kombucha and acidity have a close relationship, and you’ll know it if you’ve ever tasted a finished batch of kombucha! Because as the kombucha ferments, the acidity levels of the tea change drastically, and it’s a relationship home brewers should understand in order to make the best (safest) kombucha.

But to start – what is acidity anyways? Acidity is a measurement of hydrogen ions in a substance. When there are more hydrogen ions, the substance is more acidic.

We measure acidity on a pH scale ranging from 0 to 14. A lower pH means something is acidic, while a higher pH indicates that something is alkaline (or basic). So for reference, battery acid would be very acidic with a pH of 0, water is neutral with a pH of 7, and drain cleaner is very alkaline with a pH of 14.

Is kombucha acidic?

So is kombucha acidic or alkaline? Kombucha is considered more acidic, with a typical pH between 2.5 and 3.5.

The longer you let kombucha ferment, the more acidic it will become. This is because the yeast in the SCOBY eat the sugars in your kombucha, transforming them into ethanol. The bacteria feed on this ethanol, turning it into acidity and giving kombucha its distinctively tart taste.

How to track the pH of kombucha

While not totally necessary, you can track the pH of your kombucha if you’re worried that it might be falling outside of a safe pH range.

It’s as simple as buying some pH test strips, dipping them in your brew, and reading the pH results! Be sure to buy pH test strips that go low enough to measure the acidic kombucha (they should measure at least between 1 and 5).

When you start your first fermentation (i.e. right after you’ve combined sweet tea + starter tea), the liquid should be below pH 4.5 (is yours higher than that? read the section below). When the kombucha is finished brewing, it should be between pH 2.5 and 3.5.

But with that said, the pH is not a good indicator of when your kombucha is done fermenting. You just need your taste buds for that! After 7 days in the first fermentation, begin tasting your kombucha every few days until it is the perfect balance of sweet and tart (this is different for everyone). You can check the pH at this point to get an idea of what pH you typically like your finished kombucha to be.

How to lower the pH in kombucha

Acidity is what makes kombucha possible, in that it’s what fights off the bad bacteria! In fact, the FDA states that food under pH 4.6 doesn’t need preservatives because substances under this pH prevent bacterial growth.

Because of this, your starting kombucha needs to be below a pH level of 4.5. When you start a new batch of kombucha, you add starter tea (i.e. plain kombucha) to sweet tea to inoculate the batch. This starter tea is usually enough to bring the pH level below 4.5.

But if your kombucha is still above that level, no worries! Simply add a bit more starter kombucha until you reach a safe pH level under 4.5.

The pH level will continue to drop as the bacteria and yeast in the kombucha produce acidity.

What if my kombucha is too acidic?

Uh oh, you accidentally let your fermentation run for too long, and now your kombucha is acidic and vinegar tasting!

You can try to salvage it by adding a sweetener, like honey or sugar, then moving to the fridge to stop the fermentation.

Or simply bottle the over fermented kombucha and store it in the fridge as a strong starter. It’s likely too sour to drink, but will be a great kickstarter for future batches of kombucha.

Kombucha and acid reflux

With all this talk of acidic kombucha, you may be wondering if there’s any connection between kombucha and acid reflux.

Kombucha isn’t a great option for those suffering from acid reflux…but not entirely because of the acidity. The carbonation in kombucha expands the stomach, which can push acidic stomach acid back up, giving a burning sensation. On top of that, the caffeine and acidity of kombucha can play a role in aggravating acid reflux.

Vanilla orange kombucha in a bottle

11 thoughts on “The Quick Guide to Kombucha pH”

    • I wrote a bit on alcohol in kombucha here. You can use a hydrometer, though the readings aren’t very accurate when testing kombucha due to all the sugars and compounds in the buch. Unfortunately with kombucha there aren’t great options for testing alcohol levels (that I have found anyways).

    • You need a refractometer and an acid titration kit. Then you can measure the before and after on the sugars in the batch, and subtract the total acid. The happy herbalist has a guide.

  1. Do you recommend adding vinegar to lower the pH, if I don’t have any more starter liquid to add?
    My pH is sitting at about 5 after about 10 days of first fermentation.
    Thanks!

    Reply
  2. I have the same problem my ph is 4.5 after 10 days.
    If I add the distilled vinegar, do i move the scoby and pour it in the tea? and how much do I add?

    Reply
  3. great article, can i do my fermentations on a plastic beer fermenter and use a airlock pump to let the pressure escape?

    once again, thanks for all the tips and tricks.

    Reply
    • Hi Alex! If the plastic is fermentation safe then it should be fine. Don’t use the airlock though. Use a cloth or something breathable so air can come in and out.

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