Mold In Coffee Filter: How To Clean And Prevent

Waking up in the morning with a cup of freshly brewed filter coffee is one of life’s little luxuries.

However, what if you go to prepare your morning cup, only to find the coffee filter is covered with a layer of what looks like mold? Do you need to throw the filter away and use a paper filter instead? Is it safe to give it a quick rinse and make your morning java? Can the mold make you sick?

All these questions and more will be covered in today’s article, so keep reading!

mold in reusable coffee filter

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What kind of mold grows in a coffee filter?

There are several strains of mold that are commonly found growing in the home, these are Aspergillus, Cladosporium, and Stachybotrys Atra. These are just three of the most likely strains you can find growing in coffee filters, there are thousands of others too. They can often be recognized by their white, black, green, or blue colors and powdery textures.

One of the lesser known, but still fairly common strains of fungi found in coffee filters is called Trichoderma, a completely harmless fungus that feeds off the used coffee grounds.

This can sometimes be recognized from its vibrant green-blue color and almost “powdery” appearance. However, there are many other strains of mold that share these color and texture profiles, some of which can be hazardous to humans, so if in doubt, wear safety equipment if you plan of removing it yourself.

Can mold in a coffee filter make you sick?

Yes, molds are living organisms and some have developed a system of protection for whenever they feel threatened. Should they feel they are in danger, they can produce mycotoxins, which can be quite harmful to humans if ingested or inhaled in large enough quantities, or over a prolonged period of time.

In healthy individuals, a small amount of mycotoxin exposure will be unlikely to cause any major problems, however, if the individual has a suppressed immune system, even small amounts could cause potentially serious health concerns.

If a reusable coffee filter were not to be checked regularly and mold was being ingested on a regular basis, symptoms could include:


    • Headaches

    • Nausea

    • Breathlessness (if spores are inhaled)

    • Gastrointestinal discomfort

    • Brain fog

These are just a few of the frequently reported symptoms, there are many more, ranging from mildly irritating to potentially life-threatening. This is why it is imperative for your health that you regularly check your filter for mold and do not treat finding a colony living in it lightly.

How to clean a moldy coffee filter

Fortunately, cleaning mold out of a reusable coffee filter is a simple process that will allow it to be safely used again.

Before you begin, it is important to note that you should be wearing safety goggles, a breathing mask, and rubber gloves before you begin cleaning. This may seem a little over the top, but as you may be agitating the mold and its spores, without a breathing mask, you may otherwise end up inhaling them.

In order to clean a plastic or metal reusable coffee filter, you will need the following items:


    • Warm water

    • Detergent

    • Vinegar

    • Spray bottle

    • A scrubbing brush (or old toothbrush)

Use the following steps to make your coffee filter safe to use once again.


Step 1.

Make a solution of one part white vinegar to two parts water in a spray bottle.

Step 2.

After taking the filter apart (if applicable), liberally spray the filter with the white vinegar and water solution, ensuring every part is covered.

Step 3.

Leave the white vinegar solution to work on the filter for at least ten minutes. The vinegar is powerful enough to kill live mold and its spores.

Step 4.

Create a mixture of warm water and detergent, then using either the toothbrush or scrubbing brush, wash away any residue mold and vinegar solution.

Step 5.

Leave the coffee filter to air dry (preferably in direct sunlight), and store it away or place it back into the machine only when it is completely dry to avoid regrowth.

How to clean a moldy coffee filter with baking soda

Should you be concerned that using vinegar will create an unpleasant aftertaste in your morning coffee, you have another option in the form of baking soda.

Baking soda has a high PH level which will kill mold as effectively as vinegar does but without any unpleasant smells or potential aftertaste.

In order to use baking soda to clean a moldy coffee filter, use the following steps.

Create a solution of one cup of tap water to one tablespoon of baking soda and pour this into a spray bottle.

Agitate the solution and liberally spray it all over the filter. Leave this to sit for five to ten minutes, then rinse under wrap to remove any residual solution.

Completely dry the filter before storing it away or pacing it back into your coffee maker.

How to prevent coffee filters from becoming moldy

The most simple method to prevent mold growth in filters is to make sure it is cleaned after each use.

As soon as you have finished your cup of coffee, the filter should be removed and thoroughly cleaned, then dried to ensure no residual coffee grounds or moisture is left.

As long as you deny mold the things it needs to survive, it can not possibly grow, so starving it of moisture and nutrients is a good start.

As an additional option, you can store your coffee filter in direct sunlight, as the sun’s UV rays will kill any mold spores, this is much easier than needing to remove mold each time it grows on your filter.

Should you throw away a moldy coffee filter?

In most cases, it will not be necessary to throw away a coffee filter just because you have found mold growing in or on it. The only time you may need to is if it has been growing for a prolonged period of time and has become fully established as a colony.

In this circumstance, you may find it very difficult to completely remove mold, and it may even have penetrated deeper into a plastic filter if there are any small cracks or crevices.

If, however, the amount of mold you have found is small and has only been growing for a short period of time, using the steps provided above should be adequate to allow you to safely use this filter once again.


Can you wash and reuse coffee filters?

Yes, as long as you have followed the methods mentioned above and ensured the filter is completely clean of debris from old coffee beans and any signs of mold, you should be fine to use the filter again in your next brew. If you are unsure if the filter is completely clean and are concerned about the possibility of patches of mold being missed, you can soak the filter in vinegar for several hours. Doing this will kill any mold, so you can rest assured that the filter will be reusable without posing any threat to your health.  


How often do you need to clean a reusable coffee filter? 

To prevent mold and bacteria growth in a reusable filter, ensure that it is cleaned thoroughly after each use. Rinse out the filter thoroughly with warm water, ensuring any coffee grounds are removed, once it has dried, it will be fine to use once again. It is also well worth deep cleaning your coffee filters at least once per month, which can be done by leaving it to soak in vinegar or by placing it in the dishwasher if it is dishwasher safe, the high temperatures of the water combined with the detergent will sterilize the filter, making it completely safe to use once again.   



Coffee filters (and other pieces of coffee equipment) can be prone to mold growth if not cleaned on a regular basis and preventative measures are not taken.

Fortunately, in most cases, a filter can be easily cleaned using the steps provided in this article, so will not require you to purchase another.

Chris Walker

Chris Walker has struggled for several years with mold after buying his own property. After finding the solutions to several issues around his home, he decided to create this site in order to answer as many questions about mold and mildew as possible to help others dealing with the same problems.

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