You make kombucha by fermenting sweetened tea with a SCOBY (symbiotic culture of bacteria and yeast). Brew strong tea, dissolve sugar in it, cool the liquid, add starter liquid and the culture, then wait 7–14 days. Fermentation consumes most of the sugar, produces organic acids and a trace of alcohol, and leaves a tangy, naturally fizzy drink. Once you have a healthy SCOBY and good starter liquid, each batch practically makes itself.
What you need
You need four things: plain tea, white sugar, starter liquid, and a live SCOBY. Equipment is minimal.
Kombucha ingredient ratios by batch size. The whole recipe scales from one simple per-litre ratio. Use this as your starting point, then adjust to taste:
| Batch (water) | Tea bags | White sugar | Starter liquid |
|---|---|---|---|
| 1 litre | 2–4 | 70 g | 100–200 ml |
| 2 litres | 4–8 | 140 g | 200–400 ml |
| 1 US gallon (3.8 L) | 8–12 | 250–270 g | 400–750 ml |
| 5 litres | 10–20 | 350 g | 0.5–1 L |
Use the Kombucha Brewing Calculator to scale exact amounts for any jar size. Stick to filtered or de-chlorinated water, because chlorine stresses the SCOBY over time.
First fermentation, step by step
First fermentation is the main stage. Sweet tea becomes kombucha over 7–14 days at room temperature.
- 1Brew the tea strong Steep 3–4 black tea bags in 750ml of boiling water for 5–7 minutes, slightly stronger than you would drink it. Remove the bags without squeezing. Squeezing adds bitterness.
- 2Dissolve the sugar Stir in the sugar while the tea is still hot. Hot liquid dissolves it completely in seconds. Do not try to add sugar to cold tea.
- 3Cool completely Let the sweet tea cool below 30°C (86°F). Add cold water to bring the brew up to full volume and speed cooling. Hot liquid harms the SCOBY, so never skip this step.
- 4Add starter liquid Pour the cooled tea into your jar and stir in 100–200ml of starter liquid per litre. This drops the pH immediately, creating conditions too acidic for mould.
- 5Add the SCOBY and cover Lower the SCOBY in gently. It may sink, float, or tilt, which is all normal. Cover with breathable cloth secured by a rubber band. Keep the jar at 20–26°C, out of direct sunlight.
- 6Taste daily from day 7 Draw a small amount off with a clean straw. You want mild tang with residual sweetness, like a tart, lightly sweet tea. Most batches finish between day 7 and 14. Set aside 100–200ml per litre as starter for your next batch.
The kombucha brewing timeline
Here is how a typical first batch unfolds at room temperature (20–26°C). Warmer kitchens run faster, cooler ones slower, so treat these as a guide and taste from day 7.
| Day | Stage | What is happening |
|---|---|---|
| Day 0 | Pitch | Combine cooled sweet tea, starter liquid, and SCOBY. Starting pH is about 4.0–4.5. |
| Day 1–2 | Acidifies | The brew drops below pH 4.2 into the safe zone; a new SCOBY layer starts to form. |
| Day 3–6 | Active ferment | Tartness builds steadily as the culture consumes sugar. |
| Day 7 | Start tasting | Mild tang with residual sweetness means you are getting close. |
| Day 7–14 | Finish 1F | Pull the batch when the sweet-to-sour balance is right for you. |
| +2–5 days | Second fermentation | Optional: bottle with a little sugar or juice for carbonation. |
Second fermentation: building carbonation
Second fermentation (2F) is optional but gives you fizz and flavour. You bottle the finished kombucha with a small amount of sugar or fruit juice, seal it, and let pressure build over a few days.
- 1Bottle with headspace Fill sealed glass bottles (swing-top or screw-top), leaving about 2–3cm of headspace at the top.
- 2Add flavouring Fruit juice, fresh ginger, berries, or lemon all work well. Sugar in the juice feeds the remaining yeast, which produces CO₂.
- 3Seal and wait Leave sealed bottles at room temperature for 2–5 days. Warmer rooms carbonate faster.
- 4Burp daily Open each bottle briefly once a day to release excess pressure. This prevents over-pressurised bottles.
- 5Refrigerate Once the carbonation suits you, move bottles to the fridge. Cold stops fermentation and holds the fizz.
Use the Second Fermentation Calculator to work out sugar and juice amounts for your target carbonation level.
Starter liquid: the most important ingredient
Starter liquid matters more than the SCOBY itself. It is finished, unflavoured kombucha from a previous brew.
Adding it drops the pH below 4.5 on contact, making the environment hostile to mould and harmful bacteria. Starter also inoculates the new batch with a live population of bacteria and yeast, giving fermentation a running start.
Choosing the right tea
Your tea choice directly affects SCOBY health, fermentation speed, and flavour. The SCOBY feeds on caffeine, tannins, and nitrogen in true tea leaves (Camellia sinensis), so this decision goes beyond taste.
Read the full tea types for kombucha guide for blending ratios and brewing tips by variety.
Common first-batch problems
- Too vinegary means it fermented too long. Start tasting from day 7 and bottle sooner next time.
- Too sweet or flat means the batch needs more time, or the room is too cold. Extend by 1–2 days.
- No SCOBY forming on the surface is normal for early batches. Judge readiness by taste, not SCOBY thickness.
- Fuzzy, dry, coloured patches on top are mould. Discard the entire batch and use more starter liquid next time.
How to know your kombucha is done
Taste tells you when your kombucha is ready. Pull a small sample with a clean straw. You want mild tang with residual sweetness, something like tart apple juice.
If it still tastes like sweet tea, give it more time. Aggressively sour means it went too long.
As the brew finishes, the liquid lightens in colour. You may also see stringy yeast strands hanging below the SCOBY. Both signs are normal and healthy.
Try the calculatorBuild your exact recipe (tea, sugar, starter, and water) for any batch size.