Coffee Brewing

Why Does My Coffee Taste Sour? And How To Fix It

Written by

Erica Cervenkova

Coffee Holli Top Pick

There is nothing as refreshing as a balanced cup of coffee with a rich taste and great body. On the other hand, there is nothing as disappointing as a sour cup of coffee. It’s the easiest way to ruin your morning. 

That’s why knowing how to diagnose sour coffee and how to fix it is important. If that is what you are looking for, you are in the right place. This post covers the different causes of sour coffee and the fixes

Why Coffee Tastes Sour and How to Fix 

1. Under Extraction


The major but least understood cause of sour coffee is under extraction or short brew time. When you put ground coffee in hot water, the water extracts and dissolves the different components. 

The first components to be extracted are the sugars and acids, followed by soluble solids and oils, and finally the bitter compounds. For you to get the most delicious cup of coffee with an array of flavors and aromas, these extracted ingredients must balance each other.


If water does not pull the right balance of components to balance each other, you will get a sour cup of coffee. The sweet spot is when the bitterness and sweetness balance

On the other hand, if there is over-extraction, the coffee will be bitter. 

Brewing mistakes that cause under extraction

  • You didn’t brew long enough for the water to extract the right amount of sugars, acids and oils.
  • If the water you are using to brew your coffee is not hot enough it can lead to under extraction. Use water that is between 195 to 205 degrees Fahrenheit to accelerate extraction. 
  • There are chances of under extraction If the water is not enough to achieve the ideal water to coffee ratio.
  • A balanced extraction is achieved when the grind size is fine. The coarser the size, the harder it will be for a balanced extraction if there is not enough time. 

2. Under Roasted Beans

Achieving the perfect light roasting profile is sometimes hard. While light roasting retains the unique characteristics of the beans, it must be done perfectly. If the minimum roasting threshold isn’t met, the crisp acidity and bright flavors won’t be achieved; instead, the coffee will be sour. 

Unlike sourness caused by under extraction, which is very hard to diagnose, it’s easier to identify sourness caused by under roasted beans. Typically, the coffee will be sour, with hay or grass flavor. 

The bad news is that there is no fix for under roasted beans since you cannot reroast the beans. The only remedy is to contact the seller for a refund or replacement. 

3. Your Grinder or Brewing Method

If you are sure you did not under extract the coffee beans and that they are not under-roasted check your grinder.

If there is a build-up of oils inside the grinder, coffee can turn sour. If you grind coffee beans every day, clean the grinder every other day. 


Defective grinder burrs will produce inconsistent grounds, leading to under extraction and eventually sour coffee. 

4. Your Brewing Method

Your coffee may be getting sour because of how you are brewing. The trick here is to try different brewing methods and see if there are changes. For instance, if you have light roast beans, try the french press, immersion or Kalita wave method to test if the coffee is still sour. 

5. Coffe Beans Quality 

Another possible cause for sourness is the bean’s quality. If you bought the beans from a reputable roaster or brand, there is nothing to worry about.

6. Maybe Your Coffee is Not Sour

There is also a likelihood that your coffee is actually not sour. Maybe that’s how coffee is supposed to be. 

Can you differentiate acidic, bitter, and sour coffee? If you can’t, train your palate. The easiest way is to visit your local roaster and taste their coffee. Ask them how the coffee should taste and see if that’s how your palate perceives it. 

This is very common for people who are tasting specialty coffee for the first time. If you are used to low-grade coffee beans that are typically bitter, specialty coffee may taste sour. 

How To Fix Sour Coffee 

If your coffee is sour, start by diagnosing the cause and then find the solution. 

1. If it’s the coffee beans that are under roasted, contact the seller and ask for a replacement or refund since you can’t reroast coffee beans. 

2. If the problem is under extraction, there are several things you can do to accelerate extraction. This includes using hotter water, brewing longer, and adjusting the grind size. 

3. Another quick fix is to try different brewing methods and see if the coffee is still sour. If you realize it’s the brewing method, change to another method. 

5. Sour coffee can also be caused by oils build-up in the grinder; if this is the case, clean it properly to remove all the build-up. 


There is nothing as disappointing as a sour cup of coffee. I hope this guide has equipped you with the skills to diagnose sour coffee and the available fixes. Also, seek the opinion of a friend or family member. Your coffee may not be sour. It could be bitter or acidic, and your palate may be deceiving you. 

Frequently Asked Questions on Why Coffee Taste Sour

Why Does My Coffee Taste Sour?

The major cause of sour coffee is under-extraction or under roasted coffee beans. Make sure you are giving the coffee beans enough brewing time for the water to work on the ground coffee to extract the important components. 

How Do You Get Rid Of Sour Taste In Coffee?

To get rid of the sour taste, identify the cause and look for a remedy. If it’s because of under roasted beans, buy medium or dark roasted beans, while if it’s because of under extraction, think of what you can do to accelerate extraction. This includes brewing longer, using hotter water, and adjusting the grind size.

Can I Still Drink Sour Coffee?

Yes, coffee does not go bad. However, why would anyone want to punish their palate? 

Erica Cervenkova
Coffee Connoisseur, SCA Member

As a coffee connoisseur and member of the Specialty Coffee Association, I am dedicated to understanding the sustainability of coffee pods and the impact it has on the environment. My expertise lies in the realm of capsule coffee machines, from the likes of Keurig and Nespresso to other well-known US brands. I am passionate about sharing my knowledge and helping others make informed decisions about their coffee choices. Whether you're a coffee enthusiast or just looking for a new way to enjoy your morning cup, I'm here to help.


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