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Why Does My Coffee Taste Sour? Top Reasons Explained

Have you ever tasted your cup of coffee just for it to be bitter and sour?

You end up asking yourself, “Why does my coffee taste sour?” There are many reasons why coffee can come out bitter or sour. Let’s talk about them in detail in this post.

But first, let’s differentiate bitter from sour. When we say bitter, we are referring to the taste comparatively to tonic water. The sensation of bitterness is usually accompanied by a drying feeling in the mouth.

When it comes to sour sensitivity, we are looking at unpleasantly acidic tastes that can be compared to citric acid in lemon juice.

Keep on reading to find out why your coffee sometimes comes out sour!

What Is Coffee Extraction?

To fully understand how the taste of coffee develops, you need to know what happens in the coffee extraction process

Roasted coffee beans contain over one thousand chemical compounds. Of the grounds you brew, around 20% end up in your cup. The type and amount of chemical compounds you get depend on your coffee extraction method.

Coffee extraction simply refers to the process of pulling out compounds from the coffee grounds. The compounds that are usually extracted are plant fiber, sugars, acids, and fats. The extraction process first pulls out acids and fats. Then the sugars begin to break down followed by the plant fiber.

If you stop the extraction process too early, the coffee may not have any sugars, giving you an under-extracted brew. Over-extraction, on the other hand, will introduce plant fiber into the coffee, giving you an over-extracted brew.

The ideal coffee extraction should last just long enough to pull out fats, acids, and sugars. An under-extracted cup of coffee is usually sour, over-extracted coffee is normally bitter, and a balanced extraction gives you the best of both worlds.

Types of Coffee Extraction

These are the most popular coffee extraction methods out there.

French Press

pouring french press coffee into cup

This is an immersion extraction method. In other words, compounds are extracted from the grounds while they are submerged in hot water. The coffee is given enough time to brew, then the plunger is pressed to extract the coffee. The filter in a French Press is usually more porous to also allow the extractions of oils. But the porous nature of the filter may allow particles to pass through that’s why it is advisable to use the appropriate coarse grind setting.

Automatic Drip

automatic drip coffee maker with coffee

This method uses an auto-drip coffee maker to extract coffee. When you fill the reservoir with fresh, cold water. It flows down and levels out within the appliance. The tubing runs past the heating element, which is responsible for heating the hot plate as well as heating the water.

When the machine is on, it runs an electric current through the heating element. The temperature is kept in check by a sensor, switching it on and off to maintain an even temperature. When the water boils, it creates air bubbles that rise through the tubing. The bubbles of water are distributed over the coffee grounds and flow through to extract coffee.

Pour Over

pour over drip coffee maker kettle and cup

This is one of the easiest coffee extraction techniques. To use this method, you will need a pour-over coffee maker, a kettle, filter paper, grinder, a pour-over pot, and boiled water.

First, you need to set up the filter paper on top of the pour-over coffee maker, then add two to three scoops of medium grounds, spread the grounds outwards, use the pour-over pot to distribute hot water over the grounds. You can opt for a complex flavor by pouring the water slowly or a less complex flavor by pouring the water a little bit faster.


percolator bread and porcelain set

A percolator is a quintessential method for extracting coffee. A percolator is fitted with two chambers, an upper section with a basket for holding grounds, and a lower section for the water.

As the water heats to a boil in a percolator, it is forced up a metal stem into a filter basket filled with coarse grounds. The water passes through the coffee, drips back into the bottom of the pot, and then is forced back to the top. It continues to recirculate in this manner until the desired strength is achieved.


man holding aeropress picture

This is an incredible coffee extraction technique that uses immersion brewing technology to pull out compounds and flavors from the grounds. It usually delivers a bright, clean, smooth coffee. All you’ve got to do is add grounds into the Aeropress, then pour water over the grounds, and press the plunger to extract coffee.

Why Does My Coffee Taste Sour – Top 8 Reasons & Fixes

Have you been asking yourself, “why does my coffee taste sour?” Here are the reasons why:

1. Grind Size

Grind size determines the taste of your coffee extraction. Finer grinds usually produce more extraction, while coarser grinds create less extraction.

A finer grind exposes a larger surface area of the beans to water, allowing you to extract the fats, acids, and sugars.

A very coarse grind, however, doesn’t provide a large surface area for extraction, leaving you with a sour-tasting coffee. To fix this, consider using a burr grinder for superior consistency.

2. Brew Time

The sour taste of your coffee also depends on the brew time. A shorter brew time gives you less extraction, while a longer brew time provides more extraction.

The longer the hot water is in contact with the grounds, the more compounds are extracted, and the better tasting the coffee will be. But the shorter the water is in contact with beans, the fewer compounds will be extracted, leaving you with a sour-tasting coffee.

Some popular extraction techniques can effectively control the brew time like the French Press and Aeropress because all the hot water is in contact with the grounds until you decide it’s okay to press the plunger.

3. Coffee to Water Ratio

The coffee to water brewing ratio directly affects the taste of the extracted coffee. A higher brewing ratio will give you more extraction. A lower brewing ratio, on the other hand, will give you less extraction.

More water will effectively pull out the fats, acids, and sugars, giving you the desired taste in the coffee. But if the water is less, you will only be able to extract a few compounds from the grounds, leaving you with a sour-tasting coffee. Personal preferences and geographical locations dictate the most appropriate ratio.

4. Water Temperature

It is common knowledge that hotter water extracts more coffee as opposed to cooler water. Why does a hotter temperature give a better extraction? The molecules in hot water usually try to break free from each other to create vapor. So, when introduced into the grounds, they create friction that helps extract compounds. Lower temperatures don’t extract sufficient flavors, leaving you with sour-tasting coffee.

5. Coffee Freshness

Aroma and flavor normally deteriorate as soon as the coffee beans are roasted. Staling and deterioration become more rapid the moment you grind the roasted coffee beans because more surface area is exposed to the elements.

In other words, the fresher the beans, the better tasting the coffee will be. An opened bag of ground coffee should be disposed of after around seven days. The best thing to do is invest in a roaster, grinder, and green coffee beans. This way, you will only be roasting and grinding just enough coffee to maintain the freshness every single time.

6. Type of Water

Coffee is ninety-eight percent water. So, the type of water you use for extraction matters a lot. Fresh, cold, tap water is best for making coffee. Bottled water is ideal if the tap water has off-flavors or if the coffee extraction method tends to trap minerals. Distilled or deionized water tends to create a sour cup of coffee.

Naturally, soft water is usually best. Although, water that has been chemically softened isn’t ideal for making coffee because it filters more slowly and the sodium ions may combine with the fatty acids of the coffee beans to create soaps.

7. Under-Roasted Beans

Under-roasted coffee beans will produce sour-tasting coffee. It is nowadays a trend in the coffee community. Coffee enthusiasts refer to under roasting as a light roast. Under roasting doesn’t bring out all the different flavor components in the coffee.

A well-developed coffee bean roast is usually obtained after the first crack. The roast gets more developed after the second crack.

8. Dirty Equipment

It’s sad to say, but some people aren’t very good at cleaning coffee equipment. Dirty equipment will probably have stale remains of coffee grounds, which will directly affect the taste of your coffee. So, make sure your equipment is clean every single time.

Aside from tasting sour, your coffee could also end up with a burnt taste. Find out why coffee tastes burnt sometimes.


Can I drink sour coffee?

Yes, you can drink sour coffee, especially if it is a personal preference. But you can make adjustments to get a better-tasting coffee if that’s not your preference.

How can I fix sour instant coffee?

We recommend you mix the instant coffee with a small amount of cold water to reduce the acidity and bitterness before adding hot water.

The Bottom Line

Sour coffee is usually overly acidic because of different reasons like extra coarse grounds, a shorter brew time, a lower brewing ratio, cooler water, stale coffee, type of water, under roasting, and dirty equipment. All you’ve got to do to improve the taste is to make the necessary adjustments. For example, if your coffee tastes sour because of extra coarse grounds, you can always improve the taste by using finer grounds.

Krista Haws

Known among her friends as 'the caffeine fiend', Krista loves all things coffee. From an extremely short, strong espresso to a 3 day cold brew, Krista loves them all.

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