🍹 Fermentation • Kombucha

Sick Kombucha: Causes, Solutions & Prevention

Kombucha is a living and sparkling drink that supports digestion and immunity. Sometimes, though, your brew may smell odd, taste off, or look unusual. Don’t panic—this guide helps you diagnose, fix and prevent issues while keeping your SCOBY healthy.

🟡 Symptoms of a Sick Kombucha

Most common signs your brew needs attention:

Symptom	Description	Severity
Abnormal appearance	Dry, fuzzy mold (green/blue/black or chalky white)	High
Unusual odor	Rancid, chemical or egg-like smell	Medium → High
Off taste	Too sour, metallic or flat	Mild → Medium
No bubbles	Flat drink even after >7–10 days	Mild

🔎 Tip: Brown strings and smooth cream patches are usually yeast or a young pellicle—not mold.

🔧 Main Causes

Poor-quality ingredients

Flavoured teas or essential oils
Unrefined sugar (high mineral content)

Fermentation conditions

Temperature out of range (21–27 °C / 70–80 °F)
Direct sunlight or drafts
Reactive metal or cheap plastic vessels

Contamination

Mold or dust nearby
Improperly cleaned hands or tools

Weak SCOBY

Old / dehydrated SCOBY
Not enough acidic starter

✅ Step-by-Step Solutions

Assess severity

Visible dry mold? → discard SCOBY and liquid.
No mold? Flat or too sour → usually recoverable.

Clean & restart

Sterilise jars, funnel and strainer with very hot water.
Prepare plain black/green tea and white sugar.

Boost acidity

Add 10–20% starter (strong, acidic kombucha).
Or 1 tbsp plain white vinegar (non-flavoured).

Stabilise conditions

Keep 21–27 °C (70–80 °F)
Dark, ventilated spot; cover with breathable cloth
Taste from day 5 and adjust

🛡️ Prevention & Tips

Quality Ingredients

Unflavoured black or green tea
White sugar for consistent feeding

Good Hygiene

Wash hands & tools thoroughly each time
Cover the jar with a breathable cloth

Regular Monitoring

Check appearance & smell daily
Taste from day 5–7

SCOBY Care

Trim very old layers periodically
Store in acidic kombucha between batches

❓ Quick FAQ

How do I tell mold from yeast?

Mold is dry, fuzzy, raised (green/blue/black or chalky white). Yeast is wet, brown/cream and appears as strings or sediment. When in doubt, throw it out.

My SCOBY sinks — is that bad?

No. It can sink, float or sit mid-jar. A new pellicle forms on top if conditions are right.

My kombucha is too sour

Shorten F1 by 1–2 days, add a touch of sweetness in F2, or use this batch as starter to soften the next.

No bubbles in F2

Check bottle seal, add sugar/juice, leave 24–48 h at 20–24 °C before chilling. Use pressure-rated bottles.

Should I refrigerate the SCOBY?

Avoid it. Cold weakens the culture. Keep a SCOBY hotel at room temperature in acidic kombucha.

🎯 Conclusion

A “sick” kombucha is fixable with good ingredients, clean technique and stable conditions. Remember: it’s a living drink—each batch is a chance to learn and dial in your perfect brew.