Why Does My Pour Over Coffee Taste Sour?

Sour pour over means under-extraction. Under-extraction traces back to grind size, water temp, or brew time being too short — usually two of those three at once. Six years behind a bar taught me sourness is the first complaint you learn to diagnose. It’s the most common fixable mistake in manual brewing, and it’s almost never the gear.

What “sour” actually means in your cup

Sour isn’t the same as bright acidity. Good acidity in a Kenyan or Ethiopian coffee tastes like citrus or berries — pleasant, structured, part of the flavor. Sour tastes sharp and one-note, like biting into unripe fruit or sucking on a lemon rind. That’s acids extracting fast while the sugars and deeper flavor compounds haven’t had time to dissolve. Coffee extracts in stages: acids first, then sugars, then bitter compounds. Stop too early and you only get that first stage.

The real bottleneck: grind size, not your kettle

I get emails constantly asking if a Fellow Stagg or a Bonavita gooseneck will fix sour coffee. It won’t. Kettles control pour technique, not extraction time by themselves. What’s your grind size doing right now? That matters more than the kettle brand. Grind too coarse for pour over and water rushes through the bed and out the bottom before it can pull anything past the acids. It’s the single most common cause I see when people send me their setup.

Quick grind check

• For a V60 or Chemex, aim for medium-fine — think coarse sea salt, not table salt.
• Total brew time under 2:30 for a 1:16 ratio usually means you’re too coarse.
• Blade grinders can’t do this reliably. Inconsistent particle size means some grounds over-extract while most under-extract, and sour wins that fight almost every time.

Check your ratio and dose against SCA guidelines

SCA’s golden ratio sits between 1:15 and 1:18, coffee to water by weight. Eyeball scoops instead of weighing and you’re probably brewing weak — and weak reads as sour even when grind and time are fine. There’s not enough dissolved solid to balance the acid.

My starting point: 20g coffee, 320g water, medium-fine grind, 3:00 total brew time. Adjust from there.

Water temperature: the silent culprit

James Hoffmann’s public brewing tests show grind size moves extraction yield more than water temp does. But temp still shifts flavor balance. If your kettle reads 195°F and you’re pouring off a boil that’s actually cooled to 185°F by the time it hits the bed, you’re extracting slower and colder than you think. Sour coffee at a “correct” grind setting is often just cool water — anything under 195°F pulls acids without pulling enough sugar to balance them.

Target range: 195°F–205°F. Brewing light roasts? Stay toward the top of that range. Light roasts are denser. They need more heat and more contact time to extract properly. This is the biggest miss I see with people who roast-shop at specialty shops and then brew like they’re using a medium roast recipe.

Brew time and bloom — are you skipping steps?

A rushed bloom is a quiet sour-maker. Pour your first 40-50g of water, let it sit 30-45 seconds so CO2 escapes and grounds saturate evenly, then continue your pours. Skip the bloom and you get channeling — water finds the path of least resistance through the bed, blasts through fast, and leaves patches of under-extracted grounds pulling sour notes into the whole cup.

Don’t rule out the coffee itself

Sometimes it’s not your technique. It’s the beans. Under-roasted coffee — common with light-roast specialty bags chasing “origin character” — tastes sour no matter what you do on the brew side. Dialed in grind, ratio, and temp and it’s still sharp? Try a different bag from a different roaster before you keep tweaking your V60 technique. I’ve burned through entire bags chasing a dial-in that was never going to work because the roast itself was underdeveloped.

What I’ve found in testing

I ran identical beans across a Hario V60, a Kalita Wave, and a Chemex at the same ratio and temp. The Kalita consistently pulled less sourness at the same grind setting. Its flat bed and three-hole design slows the pour just enough to buy extra contact time without you doing anything different. If you always run a touch sour no matter what you try, switching brewers before switching grinders is a cheap fix worth testing. A Kalita Wave 185 runs $25-40 depending on material — cheaper than a bag of good coffee wasted on troubleshooting.

Direct takeaway

Start with grind size. Go one setting finer than you’re using now and see if that fixes it. It usually does. If not, weigh your dose and water instead of eyeballing it, and check your actual water temp with a thermometer instead of trusting the kettle’s display. Sour coffee is a solvable problem. It’s not a sign you need new gear.

— Nora Voss, Home Barista & Coffee Equipment Reviewer