Why Your Coffee Tastes Sour (And How to Fix It)
Sour coffee is almost always under-extraction. Learn the quick fixes, how to tell sour vs acidic, and method-specific adjustments that actually work.
Sour coffee is almost always a sign of under-extraction.
Fix it by grinding finer first, then using hotter water or brewing longer.
People also call this under-extracted coffee, sour espresso, or sour pour-over.
That means your water didn’t pull out enough of the good stuff from the grounds. You’re tasting the sharp, early flavors (lemony, grassy, thin, watery) instead of a balanced cup.
The good news: you can fix it without buying anything.
Quick answer (TL;DR)
If your coffee tastes sour, try this in order:
- Grind finer (small step)
- Use hotter water
- Brew longer (add 15–45 seconds)
- Pour slower / more evenly (for pour-over)
- Change ratio last (only if the others didn’t fix it)
Change one thing at a time so you actually learn what helped.
Sour vs acidic (important)
People mix these up.
- Good acidity = bright, juicy, pleasant (orange, berries, apple)
- Sour = sharp, harsh, thin, “this is wrong” (lemon juice + water)
Light roasts often have more acidity. That’s normal. But sour usually means the brew didn’t extract enough.
| Taste | Likely cause | Quick fix |
|---|---|---|
| Sour / sharp | Under-extracted | Go finer / hotter / longer |
| Bitter / harsh | Over-extracted | Go coarser / cooler / shorter |
| Dry / mouth-puckering (astringent) | Channeling or too fine | Improve pour / don’t over-agitate |
What causes sour coffee?
Here are the most common reasons.
1) Your grind is too coarse
Big chunks = less surface area = water can’t pull flavor fast enough. Result: sour + weak.
Fix: go finer.
2) Your brew time is too short
If water moves through too quickly, it doesn’t have enough time to extract.
Fix: brew longer (slow the flow, or steep longer).
3) Your water is not hot enough
Cooler water extracts slower. This is a super common cause.
Fix: use hotter water.
A simple rule:
- For most methods, go just off boiling (especially for light roast)
4) Uneven extraction (channeling)
Some parts of the coffee get extracted, others barely touch water. This can taste sour even if your brew time looks normal.
Fix: make sure all grounds get wet evenly:
- Good bloom
- Slow, even pours
- Don’t pour only in the center
5) Too much coffee / too little water (sometimes)
If the ratio is too strong, water can struggle to extract evenly (especially with coarse grind). But usually, ratio is not the first fix.
Fix: adjust ratio only after grind, time, and temperature.
How to fix sour coffee (step-by-step)
Step 1: Grind finer
This is the #1 fix.
- Pour-over: go 1–3 clicks finer
- AeroPress: go one step finer
- French press: go slightly finer, but not powdery (or it gets muddy)
Step 2: Brew a bit longer
Aim for a little more contact time.
- Pour-over: extend total time by 15–45 seconds
- AeroPress: steep 30–60 seconds longer
- French press: add 1 minute and stir gently
Step 3: Use hotter water
If you’re using water that’s not very hot, sour is likely.
Try 95–100°C.
If you don’t measure: water that just finished boiling, wait 0–30 seconds.
Step 4: Improve your pour / bloom (for pour-over)
A lot of sour cups come from bad wetting.
Do this:
- Bloom with 2–3x the coffee weight in water
- Wait 30–45 seconds
- Then pour slowly in circles, reaching the edges
Fixes by brew method
Pour-over (V60 / similar)
If it tastes sour:
- Grind finer
- Pour slower
- Use hotter water
- Brew a little longer
Simple target:
- 15g coffee → 250g water
- Total brew time: around 2:45–3:30 (not a strict rule, just a guide)
If your brew finishes in under ~2:30 for 15g/250g, it’s usually too fast → grind finer or pour slower.
AeroPress
Sour AeroPress usually means grind too coarse or water too cool.
Try:
- Finer grind
- Hotter water
- Longer steep (2:00 instead of 1:00)
French press
French press can taste sour if you don’t give it enough time.
Try:
- 4–5 minute steep
- Stir once at the start to wet everything
- Don’t use too-cool water
The balance rule: sour vs bitter
This is the key:
- Sour = under-extracted
- Bitter = over-extracted
So you’re looking for the middle.
If you fix sour by grinding finer, but then it turns bitter, you went too far. Back off slightly.
If you want the “bitter” side explained clearly, read Why Your Coffee Tastes Bitter (And How to Fix It).
And if you want the biggest lever in coffee taste, read How Grind Size Affects Taste (And How to Fix Bad Coffee).
Quick checklist (save this)
If your coffee tastes sour:
- Grind finer
- Use hotter water
- Brew longer
- Bloom properly (pour-over)
- Pour evenly
- Ratio last (only if the others didn’t fix it)
FAQ
Why does my coffee taste sour even when it’s strong?
Because “strong” doesn’t always mean “well extracted.” You can have strong coffee that’s still under-extracted if:
- Grind is too coarse
- Time is too short
- Water is too cool
Is sour coffee bad for you?
No, it’s usually just a taste problem. But if it’s very sour and unpleasant, it’s not a good extraction.
Can light roast coffee taste sour?
Light roasts can be more acidic and bright. But if it tastes like lemon water or “green,” that’s usually under-extraction.
