Why Your Pour Over Coffee Tastes Bitter, Sour, or Weak (and 5 Fixes That Actually Work)

You followed the recipe. You weighed the beans. You poured carefully. And yet… your pour over still tastes bitter one day, sour the next, and sometimes just watery and weak.

If that’s you, breathe. This is normal.

Pour over is beautiful because it’s precise. It’s also frustrating for the exact same reason. Small changes—grind size, water temperature, pouring speed—can swing your cup dramatically. The good news is you don’t need a new dripper or a barista certificate. You just need a clearer way to diagnose what’s happening and a handful of fixes that actually move the needle.

This guide will help you:

• identify whether you’re over-extracting, under-extracting, or extracting unevenly

• fix your cup using five simple levers

• build a reliable baseline recipe you can adjust without guessing

Let’s make your coffee taste sweet and balanced—consistently.

First: what “bitter,” “sour,” and “weak” usually mean

Before we change anything, it helps to translate your taste problem into brewing language.

Bitter / harsh / dry

This usually points to over-extraction. You pulled too much from the coffee, including harsher compounds that taste bitter or leave a drying sensation.

That “dry” feeling matters. If your mouth feels like you drank strong black tea that sat too long, that’s often a sign of over-extraction or uneven extraction.

Sour / sharp / thin

This is commonly under-extraction. You didn’t pull enough of the sweet, balancing flavors, so acidity dominates. Under-extracted coffee can taste tart, lemony in a rough way, sometimes even slightly salty.

It’s not “bad beans.” It’s usually just incomplete extraction.

Weak / watery

Weak coffee can mean two different things:

1. the coffee is under-extracted and too diluted, or

2. the ratio is simply too low (not enough coffee for the amount of water)

Weak doesn’t always mean sour. Sometimes it’s bland. Sometimes it’s both.

The sneaky one: sour and bitter at the same time

If you taste both—sharp sourness and harsh bitterness—your issue is often uneven extraction. Parts of the coffee bed are over-extracted while other parts are under-extracted. This is incredibly common in pour over.

And it’s fixable.

A quick diagnosis in 20 seconds

Ask yourself these questions after a sip:

• Does it dry your mouth?
  Likely too much extraction or too much agitation.

• Does it taste sharp and hollow?
  Likely under-extracted.

• Does it taste like hot brown water?
  Likely ratio issue (too little coffee), too fast a brew, or both.

• Is it confusing—both harsh and sour?
  Likely uneven extraction.

Now we’ll fix it, step by step.

Fix #1: Adjust grind size (the #1 most powerful change)

If there’s one lever that solves most pour over problems, it’s grind size. Not a new dripper. Not a fancy kettle. Grind size.

Here’s why: grind controls how quickly water can pull flavor from coffee. Too fine and you extract aggressively (and risk bitterness). Too coarse and water runs through too fast (and you get sour/weak cups).

If your coffee tastes bitter or dry:

Go one step coarser.

Don’t jump ten steps. Just one. Then brew again.

If your coffee tastes sour or thin:

Go one step finer.

Again, small changes are your friend.

If it’s both sour and bitter:

This often means you have too many fines (tiny particles), or your bed is channeling. In that case:

• slightly coarsen the grind

• reduce agitation (we’ll cover this)

• consider whether your grinder produces lots of fines (blade grinders are tough for pour over)

A small grind tweak is the fastest path to “oh… there it is” sweetness.

Fix #2: Nail your coffee-to-water ratio (most people are too diluted)

A lot of home brews taste weak simply because the ratio is too low.

For pour over, a dependable range is:

• 1:15 to 1:17 (coffee : water)

If you want a simple starting point: 1:16.

That means:

• 20g coffee → 320g water

• 15g coffee → 240g water

• 18g coffee → 288g water

If your cup tastes weak:

Before you blame technique, do this:

• keep the same method

• use more coffee, or slightly less water

Example:
If you brewed 15g coffee with 270g water (1:18), try 15g with 240g (1:16). That one change alone often brings the cup to life.

If your cup tastes too intense:

Don’t immediately add more water. First confirm extraction isn’t off. A coffee can taste “too strong” because it’s bitter—not because it’s concentrated.

Which leads us to temperature.

Fix #3: Adjust water temperature (make it work for you, not against you)

Water temperature is like the volume knob of extraction. Hotter water extracts more. Cooler water extracts less.

A good general range for pour over:

• Light roast: ~92–96°C

• Medium roast: ~90–94°C

• Darker roast: ~88–92°C

If your coffee tastes bitter or harsh:

Try going 2–4°C cooler.

It’s a gentle change that can smooth edges immediately.

If your coffee tastes sour or flat:

Try going 2–4°C hotter.

This helps pull sweetness and structure.

If you don’t have a temperature-controlled kettle, don’t worry. A practical workaround:

• boil water, then let it sit 30–60 seconds before brewing
  That small pause can help tame harsh cups.

Fix #4: Reduce agitation (your coffee might be “over-stirred”)

This is where many well-intentioned brewers accidentally sabotage their cups.

Pour over advice online often says “swirl” and “stir” and “agitate.” And yes, some agitation helps. But too much agitation can:

• increase extraction of bitter compounds

• create uneven flow

• dislodge fines that clog the filter, slowing drawdown and adding harshness

If your coffee tastes astringent (drying) or harsh:

Try brewing with a calmer technique:

• pour gently, in steady circles

• avoid aggressive stirring

• do one light swirl (optional), not multiple dramatic ones

Your goal is a flat, even bed—but you don’t need to “punish” it into place.

A good pour over often looks boring. That’s a compliment.

Fix #5: Control brew time and flow (too fast or too slow changes everything)

Brew time isn’t a target to obsess over, but it is a clue.

For most pour overs in the V60/Kalita style:

• a typical total time is 2:30 to 3:30 (depending on dose, grind, dripper, and filter)

If your brew finishes too fast (e.g., under 2:00):

You’re likely under-extracting.
Try:

• slightly finer grind

• slower pouring

• ensure you’re fully saturating the grounds during bloom

If your brew takes too long (e.g., over 4:00):

You may be over-extracting, or your filter is clogging.
Try:

• slightly coarser grind

• less agitation

• check if your grinder makes lots of fines

• consider filter paper differences (some flow faster than others)

Slow isn’t always good. Sometimes slow is just bitter.

Common reasons your pour over keeps changing (even when you “do the same thing”)

If your coffee is inconsistent day to day, it’s often because one of these variables is drifting:

Your grinder is inconsistent

Even small grinder differences show up in pour over. If your grinder produces lots of fines, you’ll chase bitterness and dryness more often.

Your water changes

In Japan, tap water can vary by region and even season. Harder water can mute acidity and alter extraction. Softer water can make acidity pop. If your brews feel unpredictable, water can be a silent factor.

Your beans changed (freshness matters)

Coffee is most expressive after it rests a bit post-roast, then slowly fades. Aromatics can dull first. If your “floral” coffee suddenly tastes less exciting, it might simply be aging.

You pour differently than you think

A slightly higher kettle height, faster pour, or extra swirl can change extraction and flow. Pour over is sensitive. That’s not your failure—that’s its nature.

Fix it fast: a simple troubleshooting cheat sheet

If you just want the quick answer:

• Bitter / harsh: grind coarser + cooler water + less agitation

• Sour / sharp: grind finer + hotter water + slightly longer brew

• Weak / watery: use more coffee (or less water) + slow your pour

• Dry / astringent: reduce agitation + coarsen slightly + avoid clogging

• Sour + bitter: likely uneven extraction → calm pours, reduce stirring, check grinder fines

Keep it simple. One change at a time.

The closing truth: pour over gets easier once you understand how coffee is impacted by brewing 

A great pour over isn’t about control for the sake of control. It’s about repeatable comfort. A cup that tastes sweet, balanced, and satisfying—most mornings, without drama.

Once you find your baseline, you’ll start recognizing patterns:
“This coffee wants hotter water.”
“This roast hates aggressive swirling.”
“This grinder setting is my sweet spot.”

And that’s when pour over becomes what it was always supposed to be: relaxing.

For more detailed brew guides, check out our dedicated Brew Guides by brew type here.