Why Does My Coffee Taste Metallic? 6 Common Reasons

You sit down to enjoy your morning java. Suddenly, your mouth is full of what can only be described as a metallic taste. Why does my coffee taste metallic?

Why Does My Coffee Taste Metallic
The metallic taste in your coffee may result from bad coffee beans, a low-quality roast, or a slightly off-grind

Several things can cause coffee to taste like metal. A metallic taste in your coffee may result from bad coffee beans, a low-quality roast, or a slightly off-grind. In some cases, the problem could even be your water if you’re not using filtered water to make your coffee. However, the culprit may be bacteria in your coffee maker.

Let’s dive in and figure out how to get your coffee tasting perfect again.

Why Does My Coffee Taste Metallic?

There are six primary reasons why your coffee may have a metallic taste. Understanding these will help you improve the taste of your next brew.

1. Low-Quality Coffee Beans

For the best cup of coffee, it stands to reason that you need high-quality coffee beans. What makes a high-quality coffee bean? For one thing, you need to be sure that your coffee beans are freshly roasted. How long your coffee sits on grocery store shelves (or in an Amazon warehouse) can affect the flavor of your coffee. 

Here are two factors that indicate that your coffee is freshly roasted

  • A glossy appearance that indicates that your coffee beans have plenty of acids and oils
  • An oily residue on your hands or inside the bag (light-roasted coffees have less residue)

Keep in mind that coffee beans that are made with the Swiss water process for decaffeinated coffee will naturally have a much duller appearance. Also, not all coffee beans produce the exact same amount of oil. 

2. Incorrect Extraction of the Coffee Beans

coffee, coffee beans, coffee grinder
Grinding your own coffee beans may result in over-extraction which results in having a metallic taste in your coffee

Extraction refers to the grinding of your coffee beans. If your coffee comes to you already ground, it was likely ground at a company where professional equipment perfectly extracts the coffee. However, if you grind your own coffee beans, you may be over-extracting or under-extracting your beans. 

Over-extraction of coffee beans can result in a metallic taste when the metal blades heat up during the extraction process. This is usually caused by your grinder’s metal blades being too close together. 

Under-extraction happens when the grind is too coarse. Balance your coffee grinder’s settings between fine and coarse to optimize your coffee’s flavor. 

3. Incorrect Temperature

The perfect temperature to make coffee is 205 degrees Fahrenheit (96 degrees Celcius). If your water is too hot, it can have a negative effect on your coffee’s flavors and oils. The same problem can happen if your water temperature is too low. 

4. Poorly Roasted Coffee Beans

Are you roasting your own coffee beans at home? If so, the metallic taste in your coffee may be caused by “user error.” In other words, if you’re going to roast your own coffee beans, you need to know what you’re doing. Roasting coffee beans at home is part art, part science. You need to prep, source the right ingredients, and time the roasting process. Storage matters too.

5. Poor Water Quality

Some public water supply systems produce water that has minerals that may affect the flavor of your coffee. Tap water or unfiltered water may contain minerals like manganese, calcium, and more. These minerals can cause a metallic or acidic taste in your coffee. 

For the best results, use filtered water to make your coffee. 

6. A Dirty Coffee Maker

a dirty coffee maker, a mug, a chocolate
Recommend cleaning your coffee maker at least once a month to avoid metallic taste in your coffee

In some cases, coffee may have a metallic taste if your coffee maker isn’t cleaned regularly. Believe it or not, your coffee maker may be crawling with gross mold and bacteria. If you can’t remember the last time you ran a vinegar solution through your coffee maker, it may be time for a thorough cleaning.

To thoroughly clean your coffee maker, you need distilled water, vinegar, baking soda, dishwashing liquid, a clean cloth, and a gentle scrub brush or a clean sponge. The only thing you’re going to run through your coffee maker is the vinegar and water solution. The other supplies are for cleaning the exterior surfaces of your coffee maker, your coffee pot, and the brewing basket.

Follow this guide to learn how to give your coffee maker a good scrubbing, both inside and out. If you make your coffee in a Keurig, follow these instructions to clean your machine.

To keep your coffee maker in top condition, we recommend cleaning it at least once per month.


  • Aisling O'Connor

    Aisling is an Irish food and drinks writer and journalist fueled by coffee and herbal tea. She followed up her journalism degree with nutrition studies. Find Aisling on LinkedIn.