Why Your Coffee Tastes Sour, Bitter, or Like Nothing at All

It tastes sour, sharp, or oddly salty

That's under-extraction. The acids in coffee dissolve first, and the sugars and sweetness come out after them. A sour cup is one you stopped too early. The finish is usually thin and disappears fast.

Change one thing: grind finer. Two or three clicks, not a whole turn.

Then, in order

1. Check your water is hot enough. 195 to 205°F is the standard. Off the boil and straight in, not water that's been sitting.
2. Give it longer. Slow the pour or extend the steep by 30 seconds.
3. Stir or swirl once during the brew. More contact between water and grounds means more extraction.

If it's still sour: your beans may be very fresh. Coffee in the first three or four days off roast is still full of CO₂, which pushes water away from the grounds and makes even extraction hard. Let the bag rest a few more days.

It tastes bitter, harsh, or dries out your mouth

That's over-extraction. You've gone past the sweetness and into the compounds nobody wants. It often lingers unpleasantly after you swallow.

Change one thing: grind coarser.

Then, in order

1. Drop the water temperature. Wait 30 to 45 seconds after the boil.
2. Shorten the brew. Pour faster, or plunge earlier.
3. Stop stirring. Agitation drives extraction, and most people over-agitate without noticing.

If it's still bitter: look at the roast rather than the recipe. Dark roasts are more soluble and go bitter far more easily. The same recipe that suits a light roast will overshoot on a dark one.

It's weak and watery, but it isn't sour

This is the one people get wrong, and it's worth being careful here. Weak and sour are different problems with opposite fixes.

Sour means under-extracted, so you grind finer. Weak with no sourness usually means there wasn't enough coffee in there to begin with. Grinding finer to fix it gets you a cup that's bitter and still thin.

Change one thing: use more coffee.

A common starting point for pour-over is 1 gram of coffee to 16 grams of water. That's about 60 grams per liter, or roughly 22 grams for a large mug. Weigh it once and you'll know whether you've been eyeballing low all along.

The cup is muddy, silty, or heavy at the bottom

That's fines. Every grinder makes some dust alongside the grounds you want. Cheaper grinders make more of it, and it over-extracts and slips through the filter.

Change one thing: stop swirling. Agitation is what drives fines down into the bed where they clog it.

An r/pourover regular with a first-generation Fellow Opus got a stalling, muddy brewer working with three changes and no new equipment. A flat-bottom brewer rather than conical, a 90 to 100 second bloom at three times the dose, and no swirl at any point. We covered it in Issue #6.

Rinsing the paper filter with hot water first helps too, and it warms the brewer while you're at it.

The pour-over stalls or drains far too slowly

Same cause as the muddy cup, usually. Fines have sealed the bed.

Change one thing: grind coarser.

Then check the rest

1. Pour gently. A hard central pour digs a hole and drives fines to the bottom.
2. Skip the final swirl if you've been doing one.
3. Try a flat-bottom brewer. It spreads the same amount of coffee over more filter area, so a slow bed matters less.

The espresso gushes, or chokes and drips

Espresso is the same spectrum under pressure, so it just moves faster.

Running too fast and tasting sour: grind finer. A common target is roughly double the dose in weight out, in 25 to 30 seconds. 18 grams in, 36 grams out.

Choking and tasting bitter: grind coarser.

Fast and bitter at the same time is channeling, not grind. Water has found a crack and run through it instead of the puck. Level the grounds and distribute them before tamping, and tamp flat rather than hard.

One thing that catches everyone: as a bag ages, grind finer, not coarser. Coffee that's lost its CO₂ resists water less, so an unchanged grind runs faster and under-extracts. That's why a dialed-in shot slowly turns sour over two weeks.

It's flat and dull, and nothing is obviously wrong

No sourness, no bitterness. Just not much of anything. Three suspects, in the order worth checking.

1. Freshness. The SCA's Peter Giuliano puts it at about three weeks for whole beans and about an hour for ground coffee. Grinding collapses weeks into minutes because it opens up the surface area. If you're buying pre-ground, this is your answer.
2. The harvest, not the roast. A bag roasted three days ago from a crop picked fourteen months ago is fresh and flat at the same time. Our origin buying calendar has the window for fourteen countries.
3. Your water. Coffee needs some dissolved minerals to extract properly. Distilled and zero-filter water make a famously empty cup. Very hard water goes the other way and mutes acidity into cardboard.

It's different every single morning

You're not chasing a recipe. You're chasing consistency, and that's a measurement problem.

Change one thing: weigh your coffee. A $15 scale removes the largest variable in home brewing at a stroke.

Then

1. Weigh the water too, or brew into a vessel with real markings.
2. Time the brew. Any phone does this.
3. Purge your grinder. Grinders hold a few grams of yesterday's coffee and hand it to you first.