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Scoby & Spout

Frequently asked questions

Twenty questions that come up constantly, answered directly. Where the honest answer is 'nobody publishes that', it says so.

Last updated September 1, 2026

These are the questions that turn up most often across the site. Each one links onward to the page that goes further — the short answer is here, the working is there.

FAQ

The twenty

How long does kombucha take to brew?
Seven to fourteen days for the first fermentation, driven mostly by temperature, then one to five days in sealed bottles if you want carbonation. Craft a Brew publishes exactly that 7-to-14-day window for its kit and names temperature as the variable.
What temperature should kombucha be brewed at?
Between about 75 and 85 F. Below roughly 70 F the yeast slows sharply and the batch stalls; above about 85 F it runs fast and thin and turns sour quickly.
What pH should kombucha be?
Finished kombucha typically sits between 2.5 and 3.5. A new batch should drop below about 4.2 in the first couple of days, which is the point at which it has built its own acid protection.
How do I tell mold from a SCOBY?
Mold is fuzzy, dry-looking and sits proud of the surface, usually in circular spots that are blue, green, black or white. A new pellicle is smooth, wet, flat against the liquid and often patchy or bubbly. If it is genuinely fuzzy, the whole batch and the culture go.
Why is my kombucha not carbonating?
In order of likelihood: the bottle seal is not holding, there is not enough sugar left for the yeast to work on in the bottle, or the bottles are too cold. Swing-top gaskets perish with use and are the commonest single cause.
What is the best vessel for brewing kombucha?
A one-gallon wide-mouth glass jar for batch brewing. If you want a tap, choose one whose spigot is published as 304-grade stainless steel. For continuous brewing, go to at least two gallons.
Can I brew kombucha in plastic?
Only genuinely food-grade, acid-stable plastic, and even then glass is better. Plastic scratches, and scratches hold residue you cannot scrub out. For a short second fermentation, a food-grade PET soda bottle is genuinely useful because it goes hard when pressure builds.
Is a plastic spigot safe for kombucha?
A named professional-grade plastic can be. Kombucha Kamp's published guidance names hard professional-grade plastic as acceptable and specifically warns against semi-hard plastic with a metallic coating, consumer-grade translucent white plastic, and any spigot assembled with adhesives or epoxies.
Why is brass unsafe for kombucha?
Kombucha Kamp warns that barrel suppliers sometimes fit brass spigots, which are safe with higher-pH beverages like beer but not with a liquid as acidic as kombucha. Stainless steel at 304 grade or better is the safe metal here.
What size jar do I need?
One gallon suits one or two drinkers doing batch brewing, and yields six or seven 16 oz bottles once you hold back starter tea. Two gallons or more is the working range for continuous brew.
How much starter tea do I need?
Roughly ten percent of the batch volume — about 12 to 13 fluid ounces for a one-gallon batch. Fermentaholics publishes the ten percent rule and ships 12 fl oz with its gallon culture.
Where can I buy a SCOBY?
From a dedicated culture supplier, from a general marketplace listing, or free from another brewer, since every healthy batch grows a spare. Buy from whoever publishes the volume of starter tea included, because that number is what protects your first batch.
What tea can I use?
True tea from Camellia sinensis: black, green, white or oolong. Herbal infusions are not tea and do not contain what the culture needs, and oils in heavily flavored teas build up on the culture over time.
Can I use honey instead of sugar?
Not for kombucha. Plain cane sugar is what a kombucha culture is adapted to. Honey with green tea is a different ferment called jun, which uses a different culture entirely.
What bottles should I use for a second fermentation?
Bottles built to hold pressure: swing-top or crown-cap glass designed for beer, soda or cider. The EZ Cap 16 oz amber swing top publishes a 100 PSI rating, which is the only such figure any bottle on this site states.
Is amber glass better than clear for kombucha?
For a bottle conditioning on a counter for several days, yes, because amber filters the light that degrades the drink. For finished kombucha going straight into a dark fridge it makes no practical difference.
How many bottles does a gallon fill?
About seven 16 oz bottles. A gallon is 128 oz and roughly 10 percent is held back as starter tea for the next batch, leaving around 115 oz to bottle.
Do I need an airlock?
No. Kombucha's first fermentation is aerobic and the culture needs air exchange, so the vessel is covered with a tight-weave cloth rather than sealed. An airlock is the right tool for beer and wine and the wrong one here.
Does kombucha contain alcohol?
A trace, unavoidably — fermentation produces alcohol as well as acid. Commercially sold non-alcoholic kombucha in the US must stay below 0.5 percent ABV, and homebrewed kombucha is not tested, so its exact level is unknown. If that matters for your household, treat home kombucha as containing some alcohol.
Have you tested this equipment?
No, and we never claim to have. Everything on this site is compiled from makers' and retailers' published specifications, cited to the document it came from, and scored against a published, weighted rubric you can recompute on a calculator.

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