# Why does my coffee taste sour? How to fix it

> Sour coffee is usually under-extracted: the water stopped before it reached the sugars that balance the acids. Change one thing per brew, in this order: Grind finer, then pour from higher, then raise the temperature.

Source: https://cuplift.app/fix/sour-coffee · Updated 18 October 2026

## What it means

Sourness is almost always under-extraction. Acids are the first thing to dissolve out of ground coffee; sugars and the heavier compounds that give a cup its sweetness and body come later. Stop too early and you get the acids on their own — sharp, thin, a bit like under-ripe fruit.

The fix is to extract more: finer grind, more contact, more energy in the water. Change one thing per brew so you know which one worked.

## Pour over: what to change

Pour over (V60, Chemex, Kalita Wave, Origami, Orea). Try these one at a time, in this order.

1. **Grind finer** — Go about 60 µm (2 clicks on a Comandante C40) finer. Smaller particles expose more surface and slow the water down, so it pulls more out of the coffee. Grind moves extraction more directly than anything else, which is why it comes first.
2. **Pour from higher** — A higher, more energetic pour churns the bed and pulls more from it. On a pour over, the pour is your contact-time control — the bed decides when the water leaves.
3. **Raise the temperature** — About 3°C hotter. It comes after grind and time on purpose: temperature's effect runs through extraction, and a sensory study (Batali, Ristenpart and Guinard, 2020) found tasters couldn't tell 87°C from 93°C once grind and time held extraction steady.
4. **Raise your water's mineral content** — About 20% more minerals — 150 to 180 ppm, say. Harder water extracts more and fills the cup out.

## Immersion: what to change

Immersion (AeroPress, French Press, Hario Switch). Try these one at a time, in this order.

1. **Grind finer** — Go about 60 µm (2 clicks on a Comandante C40) finer. Smaller particles expose more surface and slow the water down, so it pulls more out of the coffee. Grind moves extraction more directly than anything else, which is why it comes first.
2. **Steep for longer** — Add about 15 seconds before you press, plunge or open the valve. More contact time, more extraction — with no other side effects to untangle.
3. **Agitate more** — A few more stirs, or a swirl before you press, gets water moving through the whole bed so none of it sits under-extracted.
4. **Raise the temperature** — About 3°C hotter. It comes after grind and time on purpose: temperature's effect runs through extraction, and a sensory study (Batali, Ristenpart and Guinard, 2020) found tasters couldn't tell 87°C from 93°C once grind and time held extraction steady.
5. **Raise your water's mineral content** — About 20% more minerals — 150 to 180 ppm, say. Harder water extracts more and fills the cup out.

## Cold brew: what to change

Cold brew. Try these one at a time, in this order.

1. **Grind finer** — Go about 60 µm (2 clicks on a Comandante C40) finer. Smaller particles expose more surface and slow the water down, so it pulls more out of the coffee. Grind moves extraction more directly than anything else, which is why it comes first.
2. **Steep for longer** — Extend the steep by about 12.5% — two hours on a 16-hour steep.
3. **Raise your water's mineral content** — About 20% more minerals — 150 to 180 ppm, say. Harder water extracts more and fills the cup out.

## Worth knowing

- Sour and slow at the same time on a pour over is the exception. A drawdown that stalls while the cup still tastes sour usually means channelling — fines have clogged the bed and water is racing through a few paths, under-extracting most of the coffee while over-extracting the rest. Grinding finer makes that worse. Go coarser instead.
- A very light roast can taste bright even when it's well extracted. If it's juicy and sweet rather than sharp and thin, that's acidity, not sourness — and something to keep.

## Change one thing at a time

It's tempting to grind finer *and* raise the temperature *and* pour differently. Then the next cup is better or worse and you don't know why. One change per brew is slower on paper and much faster in practice. The [full dial-in guide](https://cuplift.app/dial-in) covers the order to fix things in when there's more than one problem.

## Questions

### Why does my coffee taste sour?

Sour coffee is usually under-extracted: the water stopped before it reached the sugars that balance the acids. Sourness is almost always under-extraction. Acids are the first thing to dissolve out of ground coffee; sugars and the heavier compounds that give a cup its sweetness and body come later. Stop too early and you get the acids on their own — sharp, thin, a bit like under-ripe fruit.

### How do I fix sour coffee?

Change one thing per brew. On a pour over: Grind finer, then pour from higher, then raise the temperature. On an AeroPress, French Press or Hario Switch: Grind finer, then steep for longer, then agitate more.

## Other tastes to fix

- [Why does my coffee taste bitter? How to fix it](https://cuplift.app/fix/bitter-coffee)
- [Why does my coffee taste dry, chalky or astringent?](https://cuplift.app/fix/astringent-coffee)
- [Why does my coffee taste weak or watery?](https://cuplift.app/fix/weak-coffee)
- [Coffee too strong or heavy? How to lighten it](https://cuplift.app/fix/strong-coffee)
- [Why does my coffee taste salty or metallic?](https://cuplift.app/fix/salty-coffee)
- [Why does my coffee taste flat or dull?](https://cuplift.app/fix/flat-coffee)