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Coffee taste bad? 15 possible reasons!

Coffee taste bad? 15 possible reasons!

We’ve all been there before and experienced that your coffee can taste bad! How is this possible you’re thinking? You’ve reviewed your process and conclude that there’s nothing that you’ve could have done better…

There are a lot of factors that can have a negative influence on your coffee taste. We will dive deeper into 15 possible reasons!

1. Bad coffee beans

Coffee beans are a huge factor in your taste of coffee.

Generally, Arabica is considered to be a high-quality coffee bean and Robusta is used more for instant coffees and other bulk manufacturing processes.

You can have bad-tasting coffee because the quality of the coffee you’re using is just not up to par. When shopping for coffee beans, get good quality beans that also have a stamp of approval from other coffee drinkers.

You can’t expect that one roast will be exactly the same as another since there are so many factors that can influence or modify it.

2. Storing the beans

Storing the beans is one the most important elements of preserving the freshness of your coffee! It’s also one of the most overlooked things in our coffee brewing journey.

Coffee beans should always be kept in a container, airtight, in order to avoid the bad coffee taste.

Also, coffee beans should be stored in a dark place or they will lose their flavor more quickly.

The amount you’ll store is important and the frequency you’re opening the container. One tip is sealing your coffee in multiple smaller containers and labeling them.

To sum this up: smaller airtight containers, keep them in a dark place, and lower the frequency you’re opening them.

3. Coffee bean grind size

The grind size of your coffee bean matters, a lot!

I’ve seen so many people that complain about their coffee tasting bad and they always blame it on:

  • Brand: it’s because of the brand
  • Coffee maker: it’s because of their cheap coffee maker, which can be of course (not cleaning it, mold, and so on…)

The coffee beans that are ground in very fine parts are more suited for espresso-based coffees like espresso, macchiatto, cappuccino, latte, breve, cortado, and so on…

Those that are ground in thicker parts are more suited for filter coffee methods like drip, pour over, and so on…

If you find your coffee bad tasting, try adjusting the grind size to see if it makes a difference or not. You’ll be surprised by the results you can do with a little tweak to the grind size!

Not every batch of coffee beans is roasted in the same way. Brewing coffee is all about consistency. Grind size and coffee to water ratio are 2 holy principles of brewing coffee!

4. Coffee bean roast type

Another one of the most frequently occurring reasons why people have a bad coffee experience is the roast type of their coffee beans. They don’t align with the grind size and brewing method they’ve chosen.

There are many variations of coffee roasts. The roast types are mostly divided into 3 categories: light, medium, and dark!


Light roasts have a light brown color and, because of the small-time of roasting, don’t have an oily surface. They generally have brighter flavors. The flavors of the bean are preserved and taste well in your coffee. If you want a more fruity taste, opt for a light roast! They respect the coffee beans’ origins, like where they’re grown. The taste is intense, acidic and preserves the natural taste of the beans


Medium roasts have a brown color and can have an oily surface, but mostly not. These coffees are known for their higher acidity, body. Like light roasts, they will preserve a lot of the beans’ original tastes but also the great taste of a longer roast. The taste is less intense, acidic, and still close to the beans’ natural taste.

Longer roasted beans generally have a sweeter taste. The more they’re roasted, the more appealing they are to specialty coffee roasters.


Dark roasts have a dark brown color and most have an oily surface. They’re lower in acids, are more bodied, and have darker tastes. The downside is that not many of the original coffee bean tastes are preserved. The newer taste is earthier, like smoke, nuts, caramel, chocolate, and so on.

Generally: the darker the roast, the less diversified tastes you’ll have because of the longer roasting time.

5. Not cleaning after descaling

This is where bad-tasting coffee might be a problem when you’re cleaning or descaling your brewer and allowing it to sit idle in between brewers. You might have done this after you’ve detected mold.

The bad taste is coming from the buildup of mineral deposits. The best way to avoid this bad coffee is by thoroughly cleaning your brewer after descaling or just changing your filters regularly! If you’re one that doesn’t use a lot of water, then grind coffee right before brewing. This will prevent bad-tasting coffee down the road.

6. Using the wrong type of water

Tap water might not be the best thing to use for coffee. Tap water is not filtered so you might opt for filtered, distilled water.

A lot of people forget this aspect and think, water is water right? Think again!

Also, the water tank of your coffee maker must also be cleaned regularly as all these things can negatively influence the taste of your water and thus the taste of your coffee.

7. Brewing at the wrong water temperature

You should be around 195-205° Fahrenheit in order to preserve the best of your coffee grounds.

If you brew at a higher temperature, you’ll have over-extraction and a more bitter taste.

Brewing at a lower temperature will result in under-extraction and thus a lower flavored coffee.

Measuring is the start of being consistent, you can measure this with a (built-in?) thermometer and start from there.

8. Unclean coffee gear and equipment

This is common sense right. As with everything else in our household, we must clean it regularly in order to increase longevity and make sure we can get the most out of it.

If you don’t have developed regular cleaning habits, start developing them now! You don’t want to suffer from coffee maker mold illness or have bad taste because of your lazy habits!

Actually, it’s crazy that people wash their cups or mug daily and don’t pay attention to cleaning their coffee maker… It’s like cleaning your plates and not your cooking pots… Makes sense right?

Do a small clean every day: your cups and your coffee maker and more thorough cleaning, at least once in a month and you’ll be glad you did.

9. Old coffee gear and equipment

A lot of coffee gear and equipment is replaced by newer ones, because of bad usage or maintenance.

Even with good maintenance and regular cleaning habits, bad coffee can be a result of old equipment. The more technical your device is, the more likely you’ll have to replace it, partly or just buy a new one.

In most cases, it’s advised to replace them with a newer machine, because they come with a warranty and other benefits. If you buy them on Black Friday or even refurbished in some cases, you can make a real deal!

10. Wrong coffee to water ratio

This is one of the most common bad coffee mistakes. As said before on Golden Sin, brewing with ratios gives you a safe zone, the range where you’ll get consistently great coffee. This needs to be tweaked to get an optimal fit for your personal taste.

If you use bad coffee to water ratio, your coffee will have a bad taste because the coffee grounds are being over-extracted due to too much water. This results in bad-tasting coffee with a thin body and more acidic tastes.

11. Used the wrong brewing method

This bad coffee mistake comes along with the bad boiling practice, bad grinding, and bad coffee to water ratio. This mistake is difficult to catch for a lot of homebrewers among us

It’s simple: You can’t just use the same brewing method all the time.

Try new things with your coffee and broaden your horizon.

You don’t brew espresso with very coarse grounds, as you don’t brew drip coffee with very fine grounds. Even if you do this, this surely will be the last time!

12. Poorly roasted coffee beans

  • Make sure the beans are heated evenly.
  • Light roasts: between 350 and 400 degrees Fahrenheit. The first stage is when you hear the first crack!
  • Medium roasts: between 410 and 430 degrees Fahrenheit. This is just before the 2nd crack happens.
  • Dark roasts: 440 degrees Fahrenheit or higher (up to 500). That’s the 2nd crack.
    Click here for more information about roast types.

13. You’re feeling sick!

If you’ve had consumed your coffee and you start to feel sick after it.

We refer to a few possible reasons for this:

  • Acids, some coffees can be really hard to digest for people and give stomach trouble. A lot of people try low-acid-coffees or organic coffee as an alternative. also, cold brew is a great alternative.
  • Mold: coffee grounds that can reach areas that are difficult to clean can be an ideal place for bacteria and mold to grow. When you feel sick, you’ll probably feel bad because of the mold in your coffee maker. Start developing a regular cleaning habit.
  • You’re really sick: you have flu, covid-19 and so: go and see a doctor for medical advice on this.

14. Using the wrong filter

Some coffee makers have permafilters or special portafilters. These can be used for multiple occasions and will serve you well. But in some cases they will be too large that they will let grounds through, resulting in a very bad taste.

Clean these filters regularly, so the grounds from last week aren’t in there, giving it a bad taste.

You can also use a paper coffee filter for better results for your drip coffee. You’ll need to find out by doing these things (experience).

15. Brewing too much coffee

This is a classic and we’ve all been there before: making a too large batch of coffee.

A lot of us will find that the longer you wait with consuming, the more flavors are lost from your coffee. However, this doesn’t mean that you should throw it away at all.

Coffee can be reheated, up to 24 hours later and still give you a good cup. That’s our line, if it’s older than a day, you’ll best throw it away.

Also, single-serve coffee makers can give you a great solution if you’re alone and want a coffee in the evening.


Why does my coffee sometimes taste metallic?

In most cases, this will be caused by using tap water. Tap water can contain substances, not visible to the eye, and influence the flavor of your water and coffee. You can solve this by using water that’s filtered.

Why does my coffee sometimes taste like plastic?

This will be because of your unclean coffee gear and equipment. Brewing and consuming coffee on a daily basis requires good and regular cleaning habits. Cleaning it after each use can be a quick fix and a more thorough cleaning every month with half vinegar and water can solve this problem. After you’ve done a deep cleaning, please run another session just with water in order to clean everything up.

Why has my coffee taste changed?

Here, we advise you can see a doctor for consultation. Have other tastes changed as well? If yes, go and get some medical advice. Is it only coffee? Chances are that you can solve it by using filtered water for brewing and (deep) cleaning your coffee gear and equipment regularly.


Now you’re equipped with the right knowledge to find out why you’re coffee taste was bad. Knowledge and consistency are 2 key ingredients for brewing great coffee.

Brewing coffee is all about control. If you implement changes, change one factor or element at a time.

Try and tweak your process of homebrewing your coffee. That’s what brewing coffee is about.

Enjoy your coffee!