Why does my coffee taste bitter and how do I fix it?
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bitter

Coffee tastes bitter when your water is too hot, the grind is too fine, or you let the coffee run through for too long. Dirty equipment or very dark-roasted beans can also produce an unpleasant, bitter flavour. The good news is that the fix is often simple: a few small changes and you'll be brewing a delicious cup again.

What causes the bitter taste in coffee?

A bitter taste in your coffee is usually down to over-extraction. That's when you draw too many compounds out of the coffee, leaving an astringent aftertaste. This can have several causes:

  • Grind too fine: this slows the water flow through the coffee, so it picks up too many bitter compounds.

  • Flow time too long: the longer the water stays in contact with the coffee, the more bitter the taste.

  • Water temperature too high: water above 96°C extracts not just the aromas, but unwanted bitters too.

  • Dark-roast or cheap beans: Robusta beans in particular are naturally more bitter than Arabica.

  • Dirty equipment: oils and coffee residue in your machine can affect the flavour.

  • Wrong coffee-to-water ratio: too much coffee for too little water gives a strong, bitter cup.


Spot one or more of these mistakes in your brewing? Don't worry — with a few simple tweaks you'll soon be making a lovely, smooth coffee again.

How do you avoid bitter coffee?

A bitter cup doesn't have to be a permanent problem. With these practical tips, your next coffee will taste much better:

  • Set the right grind size: Got a bean-to-cup machine or a separate grinder? Try a slightly coarser grind so the water flows through more freely.

  • Keep the flow time shorter: For espresso, 25 to 30 seconds is ideal. Filter coffee can take a little longer, but don't let the water stay in contact with the coffee for too long.

  • Check your water temperature: Use water between 92 and 96°C. Boil the water first and let it sit for about 30 seconds before brewing — that usually does the trick.

  • Use good-quality Arabica coffee beans: These coffee beans are generally milder and less bitter than Robusta. A medium roast is also a safer bet.

  • Clean your coffee machine regularly: Old coffee residue and oils build up quickly and affect the flavour. Rinse daily and descale every month.

  • Watch the coffee-to-water ratio: The standard guideline is around 60 grams of coffee per litre of water. That works out to roughly 7–8 grams per 125 ml cup.


With these adjustments, you'll be making a softer, more balanced coffee you'll genuinely enjoy.

Frequently asked questions about bitter coffee
Why is my coffee bitter with a fully automatic machine?
With fully automatic machines, a standard grind and brewing time are often used. If these settings are not properly matched to your taste or type of bean, the coffee can quickly taste bitter. Adjust the grind, temperature, and quantity where possible.
Does filter coffee become bitter faster than espresso?
Filter coffee has a longer brewing time, which releases more flavour compounds. This doesn’t necessarily mean bitterness, but if the grind is too fine or the water too hot, the chances increase. Use a coarser grind and check the temperature of the water.
Can milk mask the bitterness?
Yes, milk (especially whole milk) softens the bitter flavours in coffee. The fats in milk bind to the bitter components, making the taste creamier. A splash of milk or a plant-based alternative can certainly help.