Coffee tastes bitter? 10 reasons and their solutions

why coffee tastes bitter

Due to its caffeine content, coffee naturally contains bitter substances, but only a small part of this actually comes from caffeine. A certain amount of bitterness actually helps balance the acidity of the coffee. However, in a good cup of coffee, the bitter substances should not play a dominant role in the taste. Instead, it should have a variety of flavors, from floral to spicy to chocolatey. So why does coffee taste bitter? And what do you do if the coffee tastes bitter?

First, let's clarify why coffee can taste bitter. When coffee tastes bitter, it's often due to one or a combination of these three factors :

  1. Overextraction
  2. poor quality beans
  3. Water quality


Over-extraction occurs when coffee is brewed for too long or with water that is too hot, or when the grounds are ground too finely, releasing too much bitterness from the beans.

Here's how overextraction usually happens:

1. Brewing for too long

Why does coffee's bitterness increase the longer it's brewed? This is because the components of coffee are extracted at different rates during the brewing process. Some components, such as acids and sugars, are quickly extracted and dissolved, followed by oils. The bitter substances, with the exception of caffeine, are usually extracted last and become noticeable when the coffee is brewed for too long and over-extraction occurs.

There is a " sweet spot " where the coffee tastes just good, but if you brew it for too long, the additional bitter flavors come out. This is particularly common when making French press coffee , as many people tend to leave the coffee in the French press for too long. With a pour-over coffee, it's possible that the grounds are too fine and the water takes too long to drain, extending the brewing time past the sweet spot.

There is a rough estimate of brewing time for each coffee making method. Here you will find an overview of the most common brewing methods and their duration:

Brewing Method

Time (approx.)

French press

4-5 minutes

Pour over

3-4 minutes


1-2 minutes


25-30 seconds

Moka pot

5-7 minutes

Cold brew 12-24 hours

2. The beans are ground too finely

The size of the ground coffee can significantly affect the taste. If your coffee tastes bitter, it may be because the grind is too fine. This is because finer coffee particles have a larger surface area, allowing flavors and organic compounds to be extracted more quickly. The water takes much less time to saturate smaller coffee particles than larger ones. This is somewhat related to too long a brewing time, because the finer you grind, the less time you need.

Beans ground too finely are bitter

Different brewing methods require different grind settings, so it is important that you use the correct grind size for your coffee maker. If your coffee tastes bitter, consider using a slightly coarser grind than before to slow down the extraction and achieve a better flavor balance.

3. The water is too hot

Water temperature is a crucial factor when making coffee as it can significantly affect the extraction rate. If the water is too hot, the desired aromas and bitter substances are quickly released - the result is an over-extracted, bitter cup.

The ideal temperature for brewing coffee is between 91 and 96 degrees Celsius . This temperature is just below boiling point and is the point at which most flavors dissolve easily in the water. If your kettle doesn't have a thermometer, you can bring the water to boiling point and wait about 40 seconds before pouring it over your coffee.

4. Too much water in relation to the coffee

This may sound strange, because bitterness comes from coffee, and less coffee should mean less bitterness. But remember that bitterness is the result of over-extracted coffee. If you use too much water, each individual coffee grain will have access to more water than necessary, which can lead to over-extraction and a bitter taste.

If you e.g. For example, if you use too much water for a pour-over coffee, you will extract more water from the coffee grounds than necessary, resulting in a bitter taste. The extra water removes the “extra” ingredients that result in a bitter taste. Therefore, the ratio of coffee to water is a critical factor that should not be ignored.

Brewing method

Coffee-water ratio

French press

1:15 - 1:17

Pour over

1:15 - 1:18


1:15 - 1:17

Moka pot

1:10 - 1:12


1:1 - 1:2

Cold brew

1:4 - 1:8

The ratio of coffee to water is a crucial factor in the strength and taste of your coffee. Adjusting this ratio to suit your taste preferences and the brewing method you choose can result in a perfect cup of coffee.

5. Stir too much.

Stirring, shaking or swirling during the brewing process can cause the coffee to become bitter. Stirring can speed up the extraction process and over-extraction is the result. Please note: coffee is not a cocktail, so please neither shaken nor stirred!

poor quality beans

Sometimes the extraction isn't the problem, just the coffee beans. We cannot emphasize enough how important good coffee beans are to a good cup of coffee. Poor quality beans can be one of the reasons why your coffee tastes bad or bitter.

6. Robusta - Your coffee is bitter because it is Robusta.

Describing Robusta beans as inferior has more to do with the taste than the actual quality of the bean. Robusta beans are less aromatic and contain far more bitter substances than Arabica coffee beans .

This is mainly due to three factors.

  1. Robusta beans contain almost twice as much chlorogenic acid as Arabica beans, which contributes significantly to their bitterness when roasted.
  2. Robusta beans contain almost half as much sugar as Arabica beans, resulting in a less sweet taste and more bitterness.
  3. Robusta beans contain more than twice the amount of caffeine compared to Arabica beans. Caffeine tastes bitter, which also contributes to the overall bitterness of the cup.

Robusta beans are commonly found in instant coffee and espresso blends. So you might want to consider whether Robusta beans don't completely contradict your taste preferences.

7. Low quality coffee beans

Low quality coffees are beans with defects, poorly processed and/or harvested when unripe. They simply taste bitter, so we recommend purchasing specialty grade beans.

It's also worth noting that certain coffee producing regions are known for their slightly bitter coffee notes. For example, coffees from Papua New Guinea, Vietnam and Sumatra have more bitter and earthy flavors compared to the sweet and fruity coffees from East Africa, such as. B. Ethiopia and Burundi .

8. Dark roast

Bitter coffee can also be the result of improper roasting. After all, roasting is the process that extracts all the aromatic flavors from the unroasted coffee beans .

Dark roast coffee often has a more pronounced bitter taste than light or medium roast. This is because as the roasting progresses, the chlorogenic acids convert into phenylindanes, which contribute to the bitter bitterness of the coffee. The longer the coffee is roasted, the more phenylindanes are formed, making the bitterness even more pronounced.

Dunk roasted coffee tastes bitter

In addition, due to their loose structure, dark roasted coffee beans are more brittle and easier to extract, which quickly leads to over-extraction and therefore a bitter cup.

9. The water quality is not good

Poor quality water contains harmful minerals, chemicals and other compounds that negatively alter the taste of your coffee. Hard water, for example, is known to increase the bitter notes in coffee. The Specialty Coffee Association of America has established strict standards for the water used to make coffee. A good general rule is that when making coffee, you should use water that you would be comfortable drinking.

10. Your devices are dirty

Residue and oils left in coffee making equipment can go rancid over time and contribute to a bitter taste. Clean your coffee machine, grinder and other devices regularly to avoid deposits.

How to Prevent Bitter Coffee: Tips for a Better Brew

  • Use specialty beans
  • Try a medium roast. Coffee has a more balanced flavor when it is roasted to a medium strength.
  • Avoid Robusta or try a different type of Arabica bean
  • Grind coarser (use the correct grind size)
  • Use the correct water temperature
  • Adjust water to coffee ratio
  • Use Better Water (Avoid Hard Water)
  • Clean your devices regularly

By taking these factors into account, you can improve the taste of your coffee and reduce its bitterness. Gradually experiment with different variables to find the perfect balance and enjoy a more flavorful cup of coffee.