The short answer
When your first fermentation is finished, you have a few reasonable options for the SCOBY: use it in your next batch, store it in a “SCOBY hotel,” share a layer with a friend, or compost it. The most common choice is simply to keep brewing, since the culture and some of the finished kombucha, which becomes the starter liquid, are exactly what the next batch needs.
Is first fermentation done?
There is no single day count that fits everyone. Many brewers find a batch is ready somewhere between about one and three weeks, depending on warmth, the size of the batch, and how much starter liquid was used. Warmer rooms ferment faster.
To check, gently move the SCOBY aside with a clean straw or spoon and taste a small sip.
- Too sweet: give it more time.
- Pleasantly tart with some sweetness left: ready for most people.
- Sharply sour or like vinegar: it has gone past a drinking batch (see below).
Use clean utensils each time to avoid introducing contaminants.
Option 1: start the next batch
This is the simplest path. Reserve roughly a cup or two of the finished kombucha as starter liquid along with the SCOBY, make a fresh batch of cooled sweet tea, and combine them in a clean jar. Cover the jar with a tightly woven cloth or coffee filter and a rubber band. The starter liquid helps keep the new batch acidic, which discourages unwanted growth.
Make sure the tea has cooled to about room temperature before the SCOBY goes in, since heat can damage the culture.
Option 2: start a SCOBY hotel
If you want to take a break or you have spare layers, a SCOBY hotel is a jar holding one or more SCOBYs submerged in mature kombucha. Many brewers keep it at room temperature, loosely covered, and top it up with finished kombucha or fresh sweet tea occasionally. Some prefer the refrigerator, which slows the culture; sources note that a refrigerated SCOBY can be sluggish for the first few batches afterward.
If the hotel liquid becomes very vinegary, it can still serve as starter liquid in small amounts. Check it regularly for mold. Any fuzzy growth means discarding it.
Option 3: share or compost extras
Each batch usually grows a new layer. Layers can often be gently peeled apart. A spare layer, together with enough kombucha to keep it moist, makes a good gift for another brewer. If you do not need it, SCOBYs are generally fine to add to a compost pile or garden.
Can you eat or use a SCOBY?
A healthy SCOBY is made of cellulose, yeast and bacteria, and some people dehydrate or flavor pieces as snacks. Texture is chewy, and there is little reliable research on benefits, so treat this as a curiosity rather than a health measure. Only use a SCOBY that looks and smells healthy, and introduce it slowly if you try it. Skip it entirely if you have any doubts about the culture. Claims about using SCOBY on skin or in crafts are anecdotal; patch-test first if you try them.
What if kombucha ferments too long?
Over-fermented kombucha becomes very tart and less sweet, with a vinegar-like smell. It is not necessarily ruined. You can dilute it into drinks, use it as starter liquid, or let it continue into vinegar. For more on that route, see how to make kombucha vinegar. Because the acidity of homemade vinegar is not measured, avoid using it in canning or pickling recipes where tested, labeled vinegar is called for.
Signs to discard
- Fuzzy, dry or powdery spots that are green, black, blue or white on the surface (likely mold)
- Larvae or flies in the brew
- A rotten or otherwise strongly off smell
If you see mold, discard the SCOBY and the liquid, clean the jar thoroughly, and start again. Brown stringy bits, bubbles, a sunken SCOBY, and uneven bumpy layers are commonly normal.
Is it legal to sell homemade kombucha?
It depends on where you live. Rules for selling kombucha vary by country, state and local authority, and can involve cottage food or alcohol regulations, since kombucha contains trace alcohol that can rise during fermentation. Check with your local health department or agriculture authority before selling anything.