A little acidity can be a good thing. What most people mean by “sour” at home is sharp, lemony, or salty coffee with not much sweetness.
Most of the time, that is under extraction. You have not dissolved enough from the coffee.
Quick diagnosis
Pick the description that matches your cup.
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Sharp and thin: usually under extracted and low strength.
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Sharp but very strong: can be high strength with low extraction (common with espresso).
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Sharp and uneven, with a harsh finish: can be uneven extraction.
What to change first
Make one change, then retaste.
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Grind finer
This is the most reliable move across espresso and filter. -
Increase contact time slightly
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Filter: a slightly finer grind usually increases time naturally.
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Immersion: extend steep time by 30 to 60 seconds.
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For espresso only, increase yield slightly
Example: if you are at 20 g in and 40 g out, try 20 g in and 45 g out. Keep the dose stable, then adjust the grind so the shot still runs in a sensible time.
Fixes by brew method
Espresso
Sour espresso is usually under extracted, even if it looks thick.
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First move: grind finer.
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Second move: increase yield slightly.
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If it is both sour and bitter: focus on puck prep consistency before changing the recipe.
V60 pour over
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First move: grind finer.
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Keep your ratio stable.
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Aim for a slightly longer total brew time, then judge by taste.
AeroPress
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First move: grind a bit finer.
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Second move: extend brew time by 30 to 60 seconds.
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Keep stirring consistent so you can judge changes.
Plunger
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First move: grind a touch finer.
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Second move: extend brew time slightly, then decant immediately after plunging.
Links: Plunger coffee that is not muddy.
Moka pot
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First move: slightly finer grind and gentle heat.
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Make sure the basket is full and level.
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If it rushes through fast, slow the heat down.
Common causes of sour coffee
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Grind too coarse
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Brew time too short
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Water too cool
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Pouring too fast on pour over
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Espresso yield too short for the coffee
FAQs
Is sourness the same as acidity?
Not exactly. Acidity can be bright and sweet. Sour usually means sharp without balance.
Should I increase dose to fix sour coffee?
Start with grind and time first. Increasing dose often makes the drink stronger without fixing extraction.
Why is my espresso sour even when it looks syrupy?
Because appearance mostly tells you how concentrated the shot is, not how well it extracted. You can pull a thick, “strong-looking” espresso that is still under extracted, which often tastes sharp or sour.
