How to Make Kombucha

What you need

• Food-safe glass fermentation jar (transparent, so fermentation is visible)
• Loose-leaf tea strainer or brewing basket
• Breathable cover (non-woven fabric, tightly woven handkerchief, or coffee filter)
• Kettle or pot for heating water
• Pot for sterilizing equipment

Method

1. 10 minutes

   Sterilize the fermentation jar and strainer by submerging in water at approximately 100°C for about 10 minutes, or by applying sterilizing alcohol

   Raise the temperature of glass gradually to avoid thermal shock and cracking; do not pour boiling water directly into a cold jar

   Expert tipUse a transparent glass jar so you can monitor fermentation progress without opening the vessel; stainless steel grade 304 or 316 is safe but makes it difficult to observe what is happening inside

2. Place 2g of whole-leaf green tea in the strainer and set it inside the sterilized fermentation jar

   Choose whole-leaf (loose-leaf) tea over broken-leaf tea bag blends; higher-quality intact leaves produce better fermentation results

   Expert tipAny tea from the Camellia sinensis plant works — white, green, oolong, or black — and each produces a distinct flavor profile in the finished kombucha

3. Pour 600ml of water heated to 95–100°C evenly over the leaves so all the tea is saturated

4. 10 minutes

   Steep the tea for 10 minutes, then remove and discard the strainer

   The brew will taste stronger and more bitter than everyday drinking tea — this is expected and desirable for fermentation

   Expert tipThe extended high-temperature steep maximizes extraction of caffeine, which the SCOBY cultures use as a nutrient; by the time fermentation is complete, caffeine levels drop substantially below those of a normal cup of green tea

5. Add sugar or honey to the hot brewed tea and stir until fully dissolved

   Do not use artificial sweeteners or sugar substitutes — the SCOBY cultures cannot ferment them, which prevents proper fermentation and can invite mold growth

   Expert tipThe sugar is food for the cultures, not for you; residual sugar in the finished drink is low because the cultures consume the majority of it during fermentation

6. Allow the sweetened tea to cool to a safe temperature, then add the live SCOBY and starter kombucha liquid to the jar

   Hot liquid will harm the live cultures; the starter liquid is the previously fermented kombucha that the SCOBY was stored in

7. Drape a breathable cover over the mouth of the jar and secure it, then leave the jar undisturbed to ferment at room temperature

   Target an ambient temperature of 24–30°C for balanced bacterial activity; colder conditions allow yeast to outpace bacteria, disrupting flavor

   Expert tipIn summer, use a fine-weave fabric rather than a loosely woven cloth to prevent fruit flies from entering; a polyester sheet, coffee filter, or similar dense material works well

Why this works

The SCOBY is a layered colony of yeast and bacteria living in symbiosis: yeast breaks down sugar into ethanol and CO2, and bacteria convert those byproducts into organic acids that give kombucha its tang and carbonation. Brewing the tea at high temperature for a long time maximizes nutrient extraction — including caffeine — to feed the cultures rather than for drinking pleasure. The natural acidity the SCOBY generates, similar to the antimicrobial action of vinegar, protects the ferment from most competing microbes. Holding fermentation between 24–30°C keeps yeast and bacteria in balance; temperatures below this range let yeast outpace bacteria, depleting nutrients before sufficient acid can form and throwing the flavor out of balance.

Where beginners go wrong

1. 1

   Kombucha tastes flat, unbalanced, or excessively sour

   Check the fermentation temperature. Below 24°C, bacteria cannot thrive while yeast continues to work unchecked, exhausting available nutrients before bacteria can produce enough acid. Move the jar to a warmer spot within the 24–30°C range.

2. 2

   Artificial sweetener used instead of real sugar

   Discard the batch and restart using regular sugar or honey. Artificial sweeteners cannot be metabolized by the SCOBY cultures, so fermentation stalls and unwanted mold can take hold instead.

3. 3

   Mold appearing on the SCOBY or liquid surface

   Improve sterilization: boil all equipment at approximately 100°C for about 10 minutes before every batch, and ensure the breathable cover is fine-weave enough to exclude insects. Persistent mold usually points to inadequate sterilization or a cover with openings large enough for fruit flies to enter.

4. 4

   SCOBY not growing or reproducing

   Verify that real sugar or honey was used rather than a substitute, and that the fermentation environment sits within the recommended 24–30°C range. Both conditions are necessary for the cultures to be active and to form new layers.

What you should taste

Green tea kombucha ferments into a bright, citrusy drink with a clean, refreshing character similar to lemon. Black tea kombucha develops a yogurt-like tanginess with rounded depth. All versions share a sweet-tart balance and a gentle natural effervescence.

FAQ