Sour coffee is under-extracted coffee. The water left too much flavor behind in the grounds, so you taste the acids that dissolve first and miss the sugars that come later.
The good news: it's the easiest brewing problem to fix.
1. Grind finer
Smaller particles give water more surface to work on. Go one step finer on your grinder and brew again. If you buy pre-ground coffee, this is the moment a burr grinder pays for itself.
2. Use hotter water
Aim for 93–96 °C. Water straight off the boil and rested for 30 seconds lands about right. Light roasts need the top of that range.
3. Brew a little longer
Add 15–30 seconds to a pour-over, or a minute to a French press. For espresso, aim for 25–32 seconds per shot.
4. Use more coffee
A watery, sour cup can also be a ratio problem. Weigh it: start at 1 g of coffee for every 15 g of water. A scale with a timer makes this repeatable.
Still sour?
Some coffees are meant to be bright. A washed Kenyan or Ethiopian tastes of citrus and berries even when brewed perfectly. If you'd rather have chocolate and caramel, take the taste quiz and we'll match you to something rounder, like a Brazil or Guatemala.