Guide to kombucha pH

Kombucha & pH · Watch on YouTube

The short version

A common misconception is that pH can tell you when your kombucha is "done" fermenting and ready to bottle. It can't. pH is not an indicator of doneness, and it's not a measure of sweetness. The best way to test if your kombucha is done is to taste it.

Ange's pH often drops most significantly in the first few days after brewing — while the batch still tastes way too sweet. So she lets it keep fermenting. And kombucha at a given pH won't always taste the same: she's had two batches at 3.2 that tasted different because one had fermented longer and was less sweet.

So tell me more about pH…

pH is simply a measure of acidity. Kombucha pH usually drops most sharply in the days right after you start a batch. Once it's below 4, it's technically acidic enough to be considered fairly safe from mold and harmful pathogens — but it'll still probably taste too sweet to bottle. Keep fermenting until it tastes right. The drops get more incremental as fermentation progresses, and ultimately your unique taste buds decide bottling day.

What is pH actually useful for?

Confirming the process is working. A key part of kombucha-making is acidifying sweet tea with starter tea from a previous batch — that's what protects the brew from mold and pathogens while it ferments. Your brew's pH should drop below 4 in the first few days: that's the sign things are "working." (Commercial kombucha companies use pH for exactly this.) Finished kombucha typically falls between 2.5 and 3.5 — estimates, but your brew shouldn't be drastically far off.

Should I use a pH meter or test strips?

Up to you — if you're curious, by all means! Ange did: an affordable meter* and some test strips. It was fun to get another dimension of understanding in the brew cycle.

Honestly, though? In day-to-day brewing she never uses the meter anymore. New SCOBY growth around day 3–4 is the only indicator she needs that fermentation is going fine. But pH can be genuinely helpful when you want extra certainty or you're troubleshooting a struggling brew. Her logged findings, in case you're curious:

• Starting pH right after adding starter tea: 3.9–4.2
• A day or two later: 3.6–3.8
• Finished (7–12 days): 3.2–3.4

One more reason she stopped obsessing: testing pH means agitating your vessel during early F1, which is exactly when you want to leave the forming SCOBY alone.

Tips for strips and meters

• Test strips: dunk, watch the color change, read the chart. Less precise than a meter and takes some color interpretation, but plenty accurate for kombucha. Get strips that cover the low end of the spectrum — winemaking strips (measuring ~2.8–4.4) work just fine.
• Meters: prices vary wildly; don't shell out for an expensive one. Ange uses this one. Keep at least one buffer solution around — liquid at a known pH for checking accuracy. If your 4.01 buffer reads 4.05, use the little screwdriver (most meters include one) to dial it back to 4.01.
• Rinse the meter well before it goes in your kombucha. Distilled water is the official recommendation; Ange rarely has it on hand and uses filtered.

On this page, you'll find some affiliate links to sources where Ange has purchased the ingredients/materials she uses. She may get a small cut of Amazon's profit for finding + recommending them to you — it won't cost you any more than you'd normally pay. She went through a lot of trial and error to find low-cost, high-quality options to save us all money. But feel free to purchase from wherever you like!