Answer firstSour means under-extracted; bitter means over-extracted; sour and bitter together usually means channeling (water taking shortcuts) or an uneven grind. The goal is extraction that is even and balanced.
The 3-step fix: diagnose, adjust parameters, golden rules
First, taste: sour or bitter?
Sharp, sour, watery means under-extracted. Harsh, drying, ashy means over-extracted. Sour and bitter mixed usually points to channeling. Name the direction first, then adjust.
Taste is your diagnostic scale: sour ↔ balanced ↔ bitter
Why sour or bitter? The extraction order
Water pulls flavour in a fixed order: acids first, then sugars, then bitter compounds last. Stop too early and you only get sour acids; go too long and bitterness arrives. Sweetness lives in the middle.
Extraction timeline: sour early, sweet middle, bitter late
Sour AND bitter at once? Probably channeling
If the coffee bed has cracks or uneven density, water takes a shortcut: where it rushes through it over-extracts (bitter), and the rest under-extracts (sour). An evenly wetted bed gives balanced extraction.
Even wetting = balanced; channeling = sour and bitter
Fix the mechanics before touching parameters
Often it is technique, not numbers: an uneven grind, skipping the bloom, pouring too fast or in one spot, and off-temperature water. Fix these four first, then dial parameters.
Rule out first: uneven grind / no bloom / pour too fast / wrong temp
· · ·
How to adjust: sour goes finer/hotter/longer
Too sour (under-extracted): grind finer, hotter water, longer time, slightly less dose. Too bitter (over-extracted): grind coarser, cooler water, shorter time. Golden rule: change one variable at a time.
A sour, under-extracted cup: finer · hotter · longer · less dose
Symptom
Cause
Fix
Sour
under-extracted
grind finer / temp↑ / time↑
Bitter
over-extracted
grind coarser / temp↓ / time↓
Sour + bitter
channeling / uneven grind
fix distribution, pour evenly
V60 golden numbers
1:15–16
Ratio
90–94°C
Water temp
2:30–3:00
Total time
Medium
Grind (fine sugar)
The feel of sour vs bitter clicks fastest with a trainer beside you. JWC’s 1-day hands-on class dials your extraction in one afternoon.
FAQ
Why sour and bitter at once?
Channeling or an uneven grind: water rushes through gaps, over-extracting some grounds and under-extracting others. Fix bed evenness first.
How many variables at once?
Only one, so you can tell which change did what.
Light roast is very sour.
Grind finer, raise temp to 94–96°C, extend the time.
Dark roast is very bitter.
Grind coarser, lower temp to 88–90°C, shorten the time.
Dial it in, in one afternoon
Sour and bitter at home, every time?
Dial your extraction to “sweet” in one afternoon · RM199 · real gear · trainer-guided
