Why Is My Pour Over Coffee Sour? Causes and Fixes

Sharp. Thin. Like biting unripe fruit. That’s sour coffee, and when I taste it during a consult, I already know what I’m going to find before I even ask about the beans: the grind’s too coarse. Nine times out of ten, that’s the whole problem. Not the kettle. Not the roaster. The grinder.

What Sour Actually Means in the Cup

Sour isn’t bright acidity. A nice Kenyan or an Ethiopian natural tastes like citrus or berry — that’s pleasant, that’s the point. Sour is different. It’s thin and unfinished. You’ve pulled the fast-dissolving acids out of the coffee, but the water never had enough contact time or heat to dissolve the sugars that round the cup out.

CQI drills this distinction into you during cupping calibration: sourness is a defect flag, not a flavor note. Bright acidity and sour are not the same word. I’m working toward my Q Grader cert right now, and separating those two is one of the first things that clicked for me on the cupping table.

The Real Bottleneck: Grind Size

Six years behind a bar taught me grind size fixes more problems than anyone expects it to. For pour over, you want coarse sand — coarser than what most people default to from their drip machine days. Too fine chokes the flow and you get bitterness. Too coarse and the water’s through in under 2 minutes. That’s sour and weak, every time.

Standard V60 or Kalita Wave, 20g of coffee, and your total brew time comes in under 2:30? That’s your clue. Grind coarser next time — wait, I mean finer. Slower water contact needs a finer grind. Aim for 2:45 to 3:15 total brew time and taste again.

Water Temperature Is the Second Culprit

SCA’s brewing standard is 195–205°F. Drop under 195°F and extraction slows down fast — sourness spikes because the water doesn’t have enough energy to dissolve the good stuff.

Most gooseneck kettles without temp control bleed heat the second you start pouring, especially in a cold kitchen. Eyeball “just off the boil” and by the time you finish your bloom pour, you’re probably closer to 180°F. Get a kettle with a display. Fellow’s Stagg EKG holds within about 1 degree. Bonavita’s variable-temp kettles do the same job for less money.

Common Causes, Ranked by How Often I See Them

Check Your Ratio Before Anything Else

SCA’s golden ratio window runs 1:15 to 1:18, coffee to water by weight. I brew most pour overs at 1:16 — 20g coffee to 320g water. Drop to 15g coffee for that same 320g of water and you’re stretching too little coffee too far. Sourness shows up even with a flawless grind.

Get a scale. Eyeballing “about two scoops” is where half of these problems start in the first place.

James Hoffmann’s Pour Technique Matters More Than You Think

Hoffmann’s videos basically set the standard V60 method: bloom at 2x the coffee weight in water, wait 30–45 seconds, then pour in slow controlled stages instead of dumping it all at once. Skip the bloom or pour too aggressively and you get channeling — water finds the path of least resistance instead of extracting evenly. Channeled coffee tastes sour and bitter in the same cup. Sounds contradictory. It’s not. It’s just uneven extraction happening at the same time in the same brew.

Slow down. Circle from center out. Keep the bed flat. Don’t blast water straight down in one spot.

What I’ve Found in Testing

I ran identical beans through a V60, a Kalita Wave, and a Chemex side by side last year. Sourness showed up fastest in the V60 — its fast flow rate doesn’t forgive grind or pour mistakes. The Kalita Wave’s flat bed is the most forgiving for beginners because it’s harder to channel. New to pour over and landing on sour every time? Grab a Kalita Wave and grind slightly finer than you would for a V60. Easiest fix I’ve got.

I also tested the “just brew hotter” trick everyone recommends online. It works — a little. Crank temp from 195°F to 205°F without touching grind size and you’ll mask the sourness, not fix it. Rounder cup, sure. Still a band-aid. Fix grind and ratio first. Treat temperature as your fine-tuning knob, not your main lever.

Quick Diagnostic Checklist

• Total brew time under 2:30? Grind finer — coarser grind lets water through too fast, finer slows it down and extracts more.
• Brewing below 195°F? Get a temp-controlled kettle or reheat between pours.
• Using less than 1g coffee per 16g water? Add more coffee.
• Bloom under 30 seconds or skipped? Give it 30–45 seconds before your first main pour.
• Light roast, under 2 weeks old? That’s a roasting problem. No brewing fix touches it.

Direct Takeaway

Grind finer first. Weigh your dose second. Check water temp third. Don’t buy a fancier kettle before you’ve confirmed your grinder can actually produce a consistent particle size — a blade grinder or a cheap burr grinder will sabotage perfect technique every single time. Fix those three things in that order. The sourness clears up almost every time I’ve tested it.

— Nora Voss, Home Barista & Coffee Equipment Reviewer