Fixing Sour, Bitter and Weak Coffee

A symptom-to-cause table and the grind, ratio and temperature adjustments that fix each fault.

Three faults cover most bad home cups: sour, bitter and weak. Each maps to a specific direction of extraction, and each has a first adjustment that usually resolves it.

Sour or sharp means extraction is under about 18%. The water left before the sweeter compounds came out. Fix: grind finer, extend contact time, or raise temperature toward 96 °C — in that order.

Bitter or dry means extraction is over about 22%. The water kept pulling after the useful material was spent. Fix: grind coarser, shorten total time, or lower temperature toward 90 °C.

Weak or watery is not an extraction problem — it is a ratio problem. The cup is extracted correctly but diluted. Fix: lower the water-to-coffee ratio from 1:17 toward 1:15, keeping grind and time unchanged.

If sour and bitter appear together, the grind is uneven: fines over-extract while boulders under-extract. The fix is grind consistency, not a ratio change.

Change one variable at a time and brew again. Two changes at once make the result unreadable — you will not know which adjustment worked.

• Sour → under 18% → grind finer, brew longer, hotter water
• Bitter → over 22% → grind coarser, brew shorter, cooler water
• Weak → correct extraction, wrong ratio → tighten ratio toward 1:15
• Sour and bitter together → uneven grind → check grinder consistency

Further reading

• Brewing Methods Compared
• Pour-Over Step by Step