Most common causes: grind size too fine, brew time too long, water too hot, beans too dark or stale, dirty equipment. Solution: grind coarser, brew shorter, lower temperature to 92–94 °C, use fresh beans.

Why does my coffee taste bitter?

Most common causes: grind size too fine, brew time too long, water too hot, beans too dark or stale, dirty equipment. Solution: grind coarser, brew shorter, lower temperature to 92–94 °C, use fresh beans.

Why this is so

Bitterness in coffee is normal and desirable in small doses — it belongs to the flavor profile. But if bitterness dominates and masks everything else, something is wrong. The reason is almost always overextraction: too much was dissolved from the coffee grounds.

How extraction works:

Aroma compounds dissolve from the coffee grounds in a specific order: First come fruit acids and light aromas (sour, fruity). Then sugars and caramel notes (sweet, round). Finally, bitter compounds and tannins (bitter, harsh, woody). With a balanced extraction (18–22% of soluble compounds), all three groups are in balance. With overextraction, the third group dominates — and the coffee tastes bitter.

Cause and solution by brewing method:

Method	Typical Cause	Solution
Filter coffee / Pour-Over	Grind too fine, brew time too long	Grind coarser, pour faster
French Press	Contact time too long (over 4 min)	Set a timer, pour off after 4 min
Espresso	Grind too fine, shot too long	Grind coarser, stop at 25–30 s
Moka / Stovetop pot	Too much heat	Brew on medium flame, remove from stove immediately
Fully automatic	Brew temperature too high, grinder misaligned	Lower temperature, adjust grind size

Other causes:

• Water too hot: Over 96 °C extracts bitter compounds more aggressively. Ideal brew temperature: 92–94 °C. After boiling, let the kettle sit for 30–60 seconds.
• Roast too dark: Dark roasts naturally contain more bitter compounds. If your coffee always tastes bitter, try a lighter roast.
• Stale beans: After 4–6 weeks, beans lose their delicate aromas. What remains are the stable bitter compounds.
• Dirty equipment: Old coffee oils in the grinder, machine, or pot go rancid and release bitter notes. Clean regularly.

The golden rule: Always change and test only one variable. Grind size is the biggest lever — one half step coarser solves the problem in most cases.

In practice at Green Wall Coffee

At Sophienstraße 27, “my coffee tastes bitter” is the most frequent troubleshooting question from our guests. Most of the time, a simple adjustment is enough: grind coarser, brew shorter, or use fresh beans. Anyone who is unsure brings their beans and a description of their method — we help with the fine-tuning.

Related questions

• Why does my espresso taste bitter?
• What is underextraction and overextraction?
• Why does my coffee have a soapy aftertaste?

You can find more depth on this topic in the article How to make perfect espresso. Or drop by Sophienstraße 27 — Mon–Fri 8am–5pm, Sat 10am–5pm.