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Brewing kombucha at home takes about 30 minutes of active work, then 7–14 days of hands-off fermentation. The process: brew sweet tea, cool it, add a SCOBY and starter liquid, cover with a breathable cloth, wait. The main variables you’re controlling are temperature (72–80°F/22–27°C is ideal) and fermentation time (longer = more tart, less sweet). Everything else is straightforward once you do it once.
What you need
- 1-gallon wide-mouth glass jar, clear glass so you can monitor SCOBY growth without opening the vessel
- SCOBY with starter liquid, get from a friend, buy online, or grow from unflavored raw store-bought kombucha (takes 3–4 weeks)
- Black tea, 4–6 bags per gallon; black tea is the most reliable for first batches because it provides nutrients the SCOBY culture depends on
- White granulated sugar, 1 cup per gallon; avoid honey, maple syrup, or artificial sweeteners on your first batch
- Coffee filters and rubber bands, cover the jar; allows CO₂ out and air in while blocking fruit flies and dust
- pH strips or digital pH meter, test finished kombucha; target pH 2.5–3.5 before bottling
- Swing-top bottles, for second fermentation and storage
Avoid metal containers and utensils that will have extended contact with kombucha. The acidity (pH 2.5–3.5) reacts with metal over time. Glass, food-grade plastic, and wooden spoons are safe.
Step 1: Brew the sweet tea base
Bring 4 cups of water to a full boil. Remove from heat, add 4–6 black tea bags, steep 10–15 minutes, remove bags. Add 1 cup of white sugar and stir until completely dissolved. Pour in 8 cups of cool filtered water to bring the total volume to about 12 cups (just under a gallon) and the temperature down to room temperature. Verify with a thermometer, the tea must be below 85°F/29°C before you add the SCOBY. Too hot kills the culture.
Step 2: Add starter liquid and SCOBY
Pour 1–2 cups of starter liquid (finished kombucha from the previous batch, or the liquid the SCOBY came packaged in) into the cooled sweet tea. Starter liquid acidifies the brew immediately, dropping pH to a range that prevents mold and harmful bacteria from establishing before your SCOBY culture takes over. This is not optional, brewing without starter liquid significantly increases mold risk.
Gently place the SCOBY into the jar with clean hands. It may float, sink, or sit sideways, all of this is normal. A new SCOBY layer will form on the surface within a few days regardless of where the original one ends up.
Step 3: Cover and ferment
Secure a coffee filter or tightly woven cloth over the jar mouth with a rubber band. Write the start date on a piece of tape and stick it on the jar. Place the jar somewhere with ambient temperature of 72–80°F/22–27°C, away from direct sunlight and away from other ferments or fruit bowls (which carry wild yeast).
Don’t move or disturb the jar for the first 5–7 days. Moving it disrupts pellicle formation and can cause the SCOBY to form irregular shapes, though this doesn’t affect flavor.
Step 4: Taste-test starting at day 7
At day 7, insert a clean straw under the SCOBY, cover the top of the straw with your finger, extract a small sample, and taste it. At day 7 most batches are still fairly sweet with mild tartness. By day 10–12 the acidity increases noticeably. Your ideal endpoint is personal, some people prefer sweeter kombucha (stop at day 7–9), others prefer it more vinegary (day 12–14). Verify with pH strips: finished kombucha should read 2.5–3.5. Below 2.5 is very sour; above 3.5 means the SCOBY isn’t fully active yet.
| Day | Typical flavor | pH range | Best for |
|---|---|---|---|
| 7 | Mildly tart, still sweet | 3.2–3.8 | Those new to kombucha or preferring sweeter |
| 10 | Balanced tart and sweet | 2.8–3.3 | Most people’s preferred range |
| 14 | Quite tart, low sweetness | 2.5–3.0 | Vinegar-forward preference; also good starter liquid |
Step 5: Bottle for second fermentation
Remove the SCOBY and set it aside with 1–2 cups of the finished kombucha in a clean bowl, this becomes your starter for the next batch. Add any flavorings to your swing-top bottles: 1–2 tbsp of fresh fruit, fruit juice, or ginger per 16 oz bottle. Fill bottles with kombucha, leaving about 1 inch of headspace, and seal. The residual yeast in the kombucha will consume the fruit sugars and produce CO₂, creating carbonation.
Leave sealed bottles at room temperature for 2–4 days. Burp each bottle daily by opening briefly to release pressure, this lets you gauge carbonation level and prevents bottles from over-pressurizing. When the bottle feels firm and you hear a good release of pressure when opened, refrigerate. Cold stops fermentation and locks in the carbonation.
Start the next batch immediately
Don’t let your SCOBY sit out between batches. Brew a new batch of sweet tea, cool it, and add the SCOBY and starter liquid you reserved. The SCOBY stays healthiest when it’s continuously fermenting. If you need to pause, store the SCOBY submerged in finished kombucha in a covered jar in the refrigerator, this is called a SCOBY hotel. It can live this way for several months, though it becomes sluggish and needs a few batches to return to full activity after a long cold rest.
Troubleshooting common first-batch problems
No new pellicle forming after 7 days. Temperature is likely too low. Move the jar to a warmer spot (75–80°F/24–27°C). Pellicle formation slows dramatically below 68°F/20°C and may not happen at all below 60°F/15°C.
Fuzzy colored growth on the surface. Mold, green, black, orange, or pink fuzzy patches, means the batch is contaminated. Discard everything including the SCOBY; mold cannot be recovered from. For the next batch, make sure you use adequate starter liquid and that your jar and cover are clean.
No carbonation after second fermentation. Check that the bottles are actually sealing (swing-top gaskets wear out). Adding a small amount of sugar, ½ tsp per 16 oz bottle, gives the yeast more to work with. Make sure you stirred the kombucha before bottling to distribute yeast cells. Fermentis’s kombucha fermentation guide covers yeast activity and carbonation variables in detail.
I’ve found that the most common reason for flat kombucha is simply not waiting long enough, if your kitchen runs cool (below 68°F/20°C), second fermentation can take 5–7 days instead of 2–4.
Common Questions
How much alcohol is in homemade kombucha?
Typically 0.5–2.0% ABV, with most batches around 0.5–1.0%. The exact amount depends on fermentation time, SCOBY activity, and how long it carbonates. Longer fermentation and more active yeast produces more alcohol alongside more acidity. Commercial kombucha sold as “non-alcoholic” is held to below 0.5% ABV through careful fermentation control.
Can I use green tea or herbal tea instead of black?
Green tea works and produces a lighter, slightly different flavor profile. For first batches, use at least half black tea since it provides the nitrogen and minerals the SCOBY culture relies on most. Pure herbal teas, with no actual Camellia sinensis (tea plant), are not suitable on their own; the SCOBY may survive a batch or two but will gradually weaken without the nutrient profile that real tea provides.
How long does homemade kombucha last in the refrigerator?
Refrigerated finished kombucha keeps well for 2–4 weeks. It continues to slowly ferment even cold, so it gets progressively more tart over time. Most people find it’s best within the first 1–2 weeks. Carbonation also dissipates gradually in the refrigerator, so drink it while it’s still fizzy.
