What to Do if Coffee is Sour?

Have you ever had a cup of coffee that smelled great, but had a distinctly sour taste? If you haven’t, count yourself lucky. But if you know what I’m talking about, you’ll be interested to know what makes coffee taste sour and how to avoid it.

Coffee develops a sour flavor due to incorrect brewing methods or the flavor of the coffee beans themselves. The brewing process could go wrong with the water you use, the amount of time you brew your coffee, or the size of coffee grounds you use. The beans or grounds are the source of sour coffee flavor when they are harvested too early or not roasted long enough. 

I’m serious about a delicious cup of coffee, so I’m here to show you the best practices for brewing great coffee and what to do if your coffee is sour.

Why is it Happening?

Coffee that tastes sour is not bad for you, but it may be unpleasant to drink.

To understand what to do if coffee is sour, you probably need to start with the knowledge of how it gets that way in the first place.

There are a few things that can make coffee sour:

  • Water temperature – You won’t get a good cup of coffee if the water is too cold. An electric coffee maker that is wearing out, for example, may not be able to heat the water for brewing the way it once did.
  • The flavor of the beans or grounds – Light or dark roast makes a big difference in the flavor of your coffee, as does the age of the beans or grounds. Use the freshest beans possible, and store your coffee in an airtight container to extend its shelf life.

So now that you understand these broad concepts, I can dive into the most common reasons your coffee is sour, and how to prevent it.

How to Avoid Sour Coffee

Buy a darker roast

Light roasts are more acidic and have less complex flavor profiles, so the sourness in light roast coffee is easier to pick up on.

Brew it longer

Just like with bitter coffee, the problem might be under-extraction. When the grounds aren’t able to stay in the water very long, the acidity comes out, but not the oils and other flavors that balance them out.

Check your water temperature

Most likely, your water is not hot enough, resulting in an incomplete brew. Water should be around 200 degrees Fahrenheit (Approx. 93 C) to brew the perfect cup of coffee.

Use the right size grounds 

Larger grounds may not get fully extracted because water passes through them too quickly. Your coffee maker should come with recommendations about the right size grounds to use for the perfect brew.

Use fresh beans or grounds 

As soon as coffee beans are roasted, they begin to oxidize. This process makes the coffee stale, which results in a sour taste as well.

Another issue with the coffee beans is that they may have been harvested when they were too green. No matter how much they are roasted, these unripe coffee beans won’t lose their sour flavor.

Is My Coffee Sour or Bitter? And What’s the Difference?

You may have heard coffee experts use these different terms, but you really don’t understand the difference for yourself. Albeit, sour and bitter coffee does taste similar, there is a difference.

I’ve covered the topic of bitter coffee and what to do about it here.

Sourness is going to be one of the first things you notice about a drink of coffee. It will immediately feel tingly on your tongue, just like lemon or sour candy would.

Sour coffee might be described as:

  • Lemony
  • Grassy
  • Sharp
  • Stale

Bitter coffee, on the other hand, leaves an unmistakable aftertaste instead. Some people love a bold, dark roast, which is going to taste too bitter to other people.

There is no universal perfect cup of coffee. There are, however, infinite ways to brew and prepare it to achieve the flavor you like best.


Sour coffee is usually the result of the water and grounds not staying in contact long enough. Either the water passes through the grounds too quickly, or the grounds are too coarse for the water to penetrate.

If brewing isn’t the issue, then you need to check the roasting date of your coffee beans or grounds. If it is beyond a 4 or 5-week window, they may be too stale. Otherwise, check the owner’s manual of your coffee maker to see if there is a recommended ground size for the machine.

Once you have tasted sour coffee, you’ll do everything in your power not to have another cup like that. By following my recommendations above, you won’t have to!