Why Does My Coffee Taste Sour: 11 Reasons

crazy by Editorial Staff | Posted on March 7th, 2023

Are you noticing an unpleasant sour taste in your morning cup of coffee?

If so, you’re not alone. Many people have experienced this before, and it can be incredibly frustrating. But don’t despair!

sour taste

In this blog post, we’ll cover the common causes of a sour-tasting cup of coffee and the steps you can take to prevent it in the future.

Why does my coffee taste sour?

Here are some reasons why your coffee has a sour taste,

1. Short brew time

One of the main reasons why coffee can taste sour is due to a short brew time. Even if the beans were properly roasted and stored, insufficient extraction could occur if the brewing process is not done correctly. If the beans are not given enough time to brew, the flavor compounds are not fully extracted, resulting in a sour flavor. 

2. Improper grind size

If the grind size is too coarse, it can lead to a sour taste in your coffee with a bitter aftertaste.

Additionally, if the grind size is too fine, there will be too much resistance to water movement, and the extraction process will be hindered. To ensure your coffee does not taste sour, use the proper grind size for your brewing method and allow sufficient brew time.

You must ensure you’re finely grinding your coffee beans to fix this. This can be especially tricky if you’re using a manual grinder, as the grind size needs to be precise. 

3. Under extraction

If you’re experiencing a sour taste in your coffee, it could indicate that you’re not getting enough extraction and that the sweetness and bitterness are not balanced. Signs of under-extraction in coffee can include a sour taste, lack of flavor, and an oily texture.

Often, not enough flavor is taken out of the coffee grounds during brewing, resulting in a sour-tasting cup. Short brewing times can also lead to under-extraction, as the sweet flavors are not fully extracted from the bean.

To avoid this, ensure you’re grinding your beans correctly and at the right time. Additionally, use hot but not boiling water and pay attention to the brew time to ensure full extraction.

4. Over extraction

Over-extraction occurs when your coffee is brewed too long, resulting in an overly strong and acidic taste. This may be due to using too much coffee or brewing too long. To prevent this, use the correct ratio of coffee to water, and make sure you don’t brew longer than necessary.

5. Dirty coffee-making equipment

Dirty coffee-making equipment can be one of the main causes of sour-tasting coffee. Oils and solids left over from brewing can add sour and bitter flavors to fresh coffee. If these residues build up, it will cause a sour taste. To prevent this, make sure your coffee maker is cleaned regularly. Cleaning it using a descaling solution will help eliminate any residue and keep your coffee tasting fresh. 

6. Under roasted coffee beans

Under-roasted coffee beans can also be a potential cause of sourness in your cup. If the beans are roasted too lightly, they won’t experience the Maillard Reaction and will taste sour and almost hay-like.

The Maillard Reaction is a complex process that occurs when the proteins and sugars of the beans interact under high heat. If the beans are not heated to the optimal temperature and for the precise amount of time, the reaction will not happen, leaving the coffee with an unpleasant sourness.

This is why it’s important to ensure your coffee beans are properly roasted before you brew them, as this will result in a much better cup of coffee with no bitter or sour notes.

7. Old coffee beans

Old coffee beans can contribute to why your coffee tastes sour. When beans are stored for an extended period, the oils that give coffee its flavor and aroma can break down and be replaced with other flavor compounds that will affect the taste. If you suspect your coffee is tasting sour due to old beans, try using freshly roasted ones to see if that improves the taste of your brew.

8. Low-quality beans

Low-quality coffee beans are one of the most common causes of sour coffee. These beans may lack the proper flavor profile or aroma, making them less desirable to drink. 

9. Poor storage conditions

Coffee beans can be damaged or lose flavor if exposed to too much oxygen, light, or heat. If your beans are stored in a warm place or exposed to direct sunlight, they will become damaged and taste sour.

Exposure to oxygen can also quickly cause coffee beans to become stale, which results in a sour and almost hay-like flavor. This is why storing coffee beans in an airtight container, away from direct sunlight and moisture, is important. Use your coffee within two weeks of purchase for the best flavor.

10. Improper brewing techniques

Improper brewing techniques can also be a cause of sour-tasting coffee. If the grind is too coarse, the water cannot extract enough flavor from the beans. 

11. Overly hot water

When it comes to brewing coffee, the temperature of the water is just as important as other factors. If the water is too hot, it can lead to over-extraction, resulting in a bitter and sour taste. The ideal temperature for making coffee is between 195 and 205 degrees Fahrenheit.

If the water is too hot, it can cause the compounds in the coffee beans to be over-extracted and leave a burnt, bitter taste. Use water at the correct temperature to avoid this problem, and watch your brew time closely.


In conclusion, there are a few reasons your coffee might taste sour. It could be due to incorrect grind size, under-extraction, over-extraction, or too much coffee. To fix this problem, it’s important to take steps such as fine-tuning the brewing process and adjusting the grind size. By doing this, you can make sure you’re getting the perfect cup of coffee every time.


Editorial Staff

The editorial staff at Crazy Coffee Crave is a team of coffee enthusiasts & Baristas who enjoy the one thing we all think about as soon as we get up in the morning. Trusted by thousands of readers worldwide.