Does Brewed Coffee Mold?

Most people are aware that coffee is a bean, yet it is probably a good thing that most people are not aware that coffee beans are prone to growing mold. With the high temperatures that are used to brew coffee, could it be possible that brewed coffee also molds? 

So, does brewed coffee mold? Brewed coffee is just as prone to growing mold as regular coffee beans, which are grown in a warm, moist environment. While the hot temperatures that are used to brew coffee will keep mold away initially, the longer that brewed coffee sits after brewing, the more likely the beverage is to grow mold. 

Since the process of brewing coffee can be mixed between hot or cold brewing processes, it is not uncommon for people to think that coffee brewed with hot water will cause mold. However, mold responds to both heat and moisture; therefore, it is only natural for coffee brewed either hot or cold to mold. It is a complicated scenario, but this article will explore these reasons and more to uncover why brewed coffee does indeed mold. 

The Truth About Coffee and Mold

Coffee is grown in areas that are both warm and moist, which, consequently, are also the preferred environmental conditions for mold. 

Mold is a fungus that needs adequate amounts of moisture, warmth, and humidity to thrive. It also needs a food source, which in this case is the coffee. Mold prefers to grow on surfaces that contain some kind of organic matter, which can sometimes be wood or cellulose-rich structures within buildings. 

If the environmental conditions are right, and there exists an organic compound to support the mold spores, mold will grow on anything, including coffee plants. Perhaps worst of all, the mold is frequently transferred once the coffee pods are harvested and stripped down to expose the beans within. It is an inescapable process, which essentially means that coffee and mold go hand-in-hand. 

To make matters worse, through metabolic processes, mold produces a potentially deadly strain of toxins known as mycotoxins, which are spread throughout the organic matter housing the mold. It also spreads through the air, making inhalation of mycotoxins a major cause for concern. Thankfully, the prevalence of mycotoxins in mass-produced coffee beans has been heavily regulated since 2003.

To sum it up, coffee and mold are closely joined due to the environmental conditions in which coffee must have in order to grow successfully. This is certainly alarming, but the potential levels of mold and mycotoxins in the final product that you place in your coffee maker each morning are much lower than what they were before production. We are exposed to toxins on a daily basis, and the roasting process during coffee production helps to keep them very minimal. 

Why Does Brewed Coffee Mold?

Remember how mold thrives in warmth and moisture? Well, although the brewing process uses water that is considerably hot, it is not always enough to kill mold and mycotoxins. 

However, the brewing process does seem to kill a great deal of mold, which makes coffee consumption relatively safe. Even though you might be ingesting mold, it is not anything beyond your daily exposure to toxins that occurs as you go about your day. 

The real issue with mold and brewed coffee with milk or water is likely to come from coffee that has been left to sit for a considerable amount of time. 

Since mold is already likely to be within the ground coffee, the mold simply needs to ferment in the stagnant coffee to become noticeable. If you have ever forgotten to empty your coffee grinds in the coffee pot, you probably noticed mold growing on the coffee after a few days . 

Cleaning your coffee pot, emptying out the water reservoir, and cleaning the tank is also recommended to prevent mold from forming. If you want to prevent mold from brewed coffee, you could also consider purchasing coffee beans that have been rigorously roasted, as the roasting process reduces mold greatly

So, even though the brewing process aids previously roasted coffee beans in killing additional mycotoxins, the propensity for brewed coffee to mold is still very much possible due to the previous exposure of the coffee plants to mold. 

If you’re scared of mold, this news might be alarming. Is there a time frame for ingesting coffee before mold begins to grow? Let’s find out below. 

How Fast Does Brewed Coffee Mold?

The speed at which brewed coffee molds depends greatly on what conditions caused the mold in the brewed coffee to begin with. 

Either way, be it from letting the coffee sit too long or previously infected coffee beans, the process for mold to appear is not immediate. 

If the growth is due to normal accumulations of mold in beans that were not already carrying mold, you can typically expect to see mold in brewed coffee within three days, perhaps two if your home is warm.

Remember, all it takes for mold to form is warmth, moisture, and organic matter. The mold will need to begin feeding on the coffee and growing outwards due to the favorable conditions found within a coffee maker. 

If kept in the coffee maker, the coffee grounds will likely mold much quicker than liquid coffee. This is due to the brewing process and the liquid form of the coffee. 

If you want to avoid issues with mold, brewed coffee should always be consumed within 24 hours. And this suggestion isn’t just mold-related; who wants to drink day-old coffee?

The Verdict: Brewed Coffee Does Mold

It is not easy to digest (both figuratively and literally), but coffee does, in fact, mold. 

Brewed coffee is no exception to this unfortunate fact. Mold is simply a part of nature and biology. There isn’t much that can be done to eradicate it, and coffee needs the environmental conditions to grow that also happen to be the favorite conditions of mold. Thankfully, the mold that is found in coffee is tightly regulated during the production process. 

Even with those regulations, the mold is not completely destroyed by the roasting process. Even worse, mycotoxins are prone to attach to coffee plants and beans; therefore, it is somewhat inescapable to truly separate mold from coffee. 

Fortunately, the levels of mold in your brewed coffee are considerably low. You have nothing to worry about, especially as the strong acidity of your stomach is more than capable of destroying the mold. However, it’s important to know that the brewing process alone doesn’t completely neutralize the mold.

So, where is the solution in all of this? 

Well, knowing that the mold in coffee will not severely harm you is the best comfort that can be found with this issue. Just remember to always consume your coffee within 24 hours of brewing it, and all will be okay in the long run.  


To recap, brewed coffee molds in two primary ways:

  • From previously molded coffee beans during the growing process
  • From brewed coffee that sits out too long and develops mold

There isn’t much in the way to avoid the first point, but you can easily avoid molded coffee by not ingesting coffee over 24 hours old. 

There is no silver-lining in hoping that the hot brewing process alone will kill any of the molds. Ensure that your coffee maker is as clean and dry as possible and remember to make as much coffee as you plan to drink within a day. If you leave it to sit in the pot for a few days, you’re going to find mold. 

Tim S.

Tim loves roasting, brewing, and experimenting with coffee. After years of perfecting this craft, working as a barista, and owning a small coffee service in college, he has decided to share his knowledge with the world.

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