Coffee Maker Mold Is Making You Sick!

Tara Williams

Food Writer & Editor For KitchenSanity

Tara Williams is a seasoned food writer and editor who's been with KitchenSanity since its beginning. With a knack for experimenting with food and creating delicious recipes, she's your go-to for straightforward kitchen advice and practical tips from personal experiences. As a mom of two, Tara understands the value of time. She crafts articles that enhance your cooking skills and free up time for what matters most—like family moments.

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If you’re drinking coffee that’s brewed in machines that aren’t cleaned properly, there’s a very good chance that coffee maker mold is making you sick!

Ignoring the bacteria that thrives in the warm, moist equipment allows it to accumulate and move closer to causing very real health concerns.

In fact, ignoring your coffee machine for even a single weekend without giving it the most basic cleaning is long enough to develop an unhealthy situation. Mold spores multiply the fastest when their environment is sitting idle.

Is Mold Living In Your Coffee Maker?

There’s an overwhelming tendency to assume that a bad cup of coffee is the result of a bad batch of roasted coffee beans or a severely malfunctioning coffee maker. The alarming truth is that the awful taste is probably an indication that the coffee maker is harboring harmful mold.

Related | Can Coffee Go Bad?​

The first sign of mold in the coffee maker is apt to be bitter-tasting java, according to Terri Newcom, Director of Perdue Extension in Indiana’s Tipton County. But, there’s a much greater concern than bitter-tasting coffee.

Newcom warns coffee drinkers that there are health risks associated with ingesting the mold spores that are poured right along with your joe from an unclean coffee machine.

Health Issues Caused By Coffee Maker Mold

Ingesting coffee mold spores can trigger allergies.

Headaches, congestion, coughing, sneezing, watery eyes and umpteen more allergy symptoms can all be brought on by a foul cup of moldy coffee.

It can also be responsible for the onset of flu-like symptoms and upper respiratory infections!

If you’re a coffee drinker and you’re experiencing gastrointestinal issues, it just might be the coffee maker that’s making you sick.

Feeling bloated? Experiencing discomfort from gas? Sidelined by sudden diarrhea? Have you recently had a cup of coffee? Suspect a dirty, moldy coffee machine!​

About Half Of All Coffee Maker Reservoirs Are Breeding Mold

The findings of a study titled ‘Germiest Places In The Home’ and released by NSF International in May, 2011 are disturbing. The coffee maker reservoir ranks germier than your pets ‘ toys, the light switches located in your bathroom and the flush handles on your toilets.

Just imagine! Stirring your coffee with Fido’s chew toy might contaminate the toy more than it taints your cup of coffee! How disturbing is that?

Leaving the top of the reservoir open to accommodate the evaporation of moisture helps a little but it doesn’t address the contamination of the tubing at all. And, don’t even think of wiping the reservoir dry with a cleaning cloth for the same reason they shouldn’t be used to clean coffee mugs.

Dr. Charles Gerba, a microbiologist and expert on hygiene, has studied bacteria on coffee mugs and the results will make your skin crawl.

  1. Half of the coffee mugs had fecal bacteria, likely from contaminated cleaning cloths.
  2. Filtration, hot water and coffee acidity don’t combat the health risks of dirty coffee makers​

Some coffee brewing systems use activated charcoal for built-in water filtration. They are great at removing solids like minerals and chemicals but they don’t eradicate harmful organisms.

As for the solids, the degree of removal varies with the type of filtration system and the filters that are used.

Hot water won’t completely annihilate germs unless it’s sustained at the boiling point for a minimum of sixty seconds. Coffee brewers simply don’t reach anywhere near this temperature.

It’s true that the acidity of coffee makes it antibacterial to some degree. However, according to Donna Duberg, the ‘St Louis Germ Expert’, there are research studies concluding that brewing with roasted beans is only approximately 50% effective in killing bacteria.

When it comes to unroasted (green) coffee beans, there is no evidence of any antibacterial properties at work at all.

Why Clean Your Coffee Maker If There Are No Signs Of Mold?

There are four primary reasons to routinely and properly clean your coffee maker:​

  1. Kill germs and preserve your health! What you don’t see can hurt you!
  2. Keep the coffee machine working properly and extend its life.
  3. Maintain a consistent brewing temperature by ensuring unrestricted water flow.
  4. Protect the integrity of the coffee flavour.​

Recommended Routine Cleaning of Coffee Makers

  • After Each Use: Remove the wet coffee grounds and rinse the filter basket – they harbor and nurture mold spores.
  • Daily: Wash the carafe, lid and filter basket every day. Warm, sudsy water is all it takes.
  • Weekly: Wash all of the removable components a minimum of once per week; more if the coffee machine is used frequently. It’s as fuss-free as using hot, soapy water followed by a rinse and then letting it all air dry. As an alternative, put it all through the dishwasher (top rack only) on the hottest setting. This routine cleaning will significantly reduce bacteria and oils that have accumulated. It will also remove stains and keep your coffee maker looking cared for.
  • Monthly: Running one part vinegar/one part water through the brewing cycle will combat molds and germs and decalcify the tubing. Start the brewing cycle with the mixture in the reservoir, stop the process at the halfway point and let it stand for about one hour. Then, continue the cycle. Before brewing coffee in the machine, run at least two complete cycles with plain water to clear the components of the acidic taste. (vinegar is 5% acetic acid)

Note: Coffee machines in soft water locations can go up to 3 months without the vinegar cleaning process.

What To Use To Clean Your Coffee Maker

Distilled White Vinegar

Carolyn Forté, Director of the Home Appliances Cleaning Products Lab at Good Housekeeping Research Institute recommends vinegar as the most effective product to clean your coffee machine.

What are the advantages of using distilled vinegar?

  1. It sanitizes
  2. It decalcifies (removes mineral build-up)
  3. It’s easy to rinse from the coffee machine
  4. It’s inexpensive​

Baking Soda And Lemon Juice

baking soda and lemon

Lemon has the same acidity and the same cleaning strength as vinegar. The process is exactly the same. Some coffee lovers actually like the taste when a trace of lemony flavor comes through in the first follow-up brewing cycle.

The only drawback to this method is the fuss and/or the cost. Using fresh lemons requires squeezing a lot of lemons to get the amount of juice required. Bottled lemon juice cuts down on the effort and the mess but it’s far more expensive than distilled white vinegar.

Baking soda can be more of a problem than a solution. It’s best used on the exterior parts of the coffee maker because it only takes a minor amount of undissolved powder to cause a major problem.

It can further clog an already sluggish coffee machine as particles get hung up on the existing scale and contaminants. Also, the taste of the coffee can be compromised for a long, long time as it’s difficult to rinse it completely out of the line. In fact, it might seem impossible. You’ve been warned!​

URNEX or similar commercial cleaning products for various types of coffee makers, including Espresso and Single Serve units provide a deeper cleaning. To remove oily residue, it’s recommended to use one packet of cleaning powder once per week. They’re biodegradable, odorless and made of natural ingredients.

If used as recommended, they can be costly! Knowing that homemade solutions can’t remove the oily residue from coffee makers, it’s probably worth a compromise.

Consider using the make-it-yourself solutions most of the time but de-grease the coffee equipment with a commercial product some of the time. After all, with every brew cycle, residual oils from the coffee grounds are manipulating the outcome of the flavor!

There is also a descaling powder with a recommendation for usage of about every 3 months. This is much more affordable. There are two treatments per package, so you would need 2 boxes per year.

However, the homemade treatments do an okay job at descaling and a commercial product isn’t likely to do much better.​

How To Clean Pod Type Coffee Makers Like Keurigs

There are more components at risk of becoming clogged by oils and grime and developing harmful mold in these brewers.

Check out our Keurig Troubleshooting guide for tips and fixes for keeping your Keurig clean.

“Keurig mold” is possibly what brought you to this page.

Cleaning discs and K-cups are available for single serve coffee machines such as Keurig and Tassimo (see our K Cup Coffee Maker Reviews for models and comparison).

But, are special cleaning products really necessary?

They can be cleaned just like any other coffee maker by using the vinegar method. However, when the manufacturer has advised you against using an acidic product to clean the machine, it signals that doing so can potentially cause serious damage to sensitive components and void any warranty.​

The key to safely using the vinegar cleaning process is to further dilute the typical solution to make it safe for use with the Keurig, Tassimo and similar brewers.

Never use more than one part vinegar to two (or even three!) parts water. Just keep in mind that using any amount of vinegar can void your warranty if the manufacturer specifically instructs you to not use it. So, use it at your own risk.

Some brewers won’t allow the brewing process to commence without a pod or a disk in place. Use a K-Cup pod holder without a coffee pod. Tassimo includes a ‘service disc’ that can be used to allow the machine to function without coffee.​


Healthy Habits Go Beyond Cleaning The Coffee Machine

It’s important to use a clean cup every time! When a dirty cup is placed on the machine, bacteria is transferred to the coffee maker and the coffee cups that follow! Office coffee mugs are typically neglected.​

  • Take your coffee cup home.
  • Put it through the dishwasher or clean it well by hand with antibacterial dish liquid and let it air dry.
  • Do not re-contaminate it with a drying towel!​

Also, the drip trays on Keurigs and similar machines should be cleaned routinely.

Keep Your Coffee Mold Free! Spread The Word!

If you really think about it, you can probably recall having coffee away from your at-home clean coffee equipment and feeling out of sorts afterwards.

Sudden diarrhea? Cramps? Congestion? Headache? Now you know there’s a very real probability that you drank coffee from a contaminated machine – or pot – or mug!

How many coffee drinkers don’t know there’s a likely connection between coffee time and the onset of physical discomfort? Even one is too many! Let everyone in your circle know, so they can let everyone in their circles know, so…​

It isn’t enough to clean your own at-home coffee maker if you have coffee at the office, community gatherings and at the neighbour’s homes. Are those coffee makers regularly cleaned, too?

Spread the word to promote coffee being served with froths, syrups, creamers and sweeteners – and sans mold! Hopefully, you’ll never again say coffee maker mold is making you sick!​

Written By Tara Williams

Tara Williams is a seasoned food writer and editor who's been with KitchenSanity since its beginning. With a knack for experimenting with food and creating delicious recipes, she's your go-to for straightforward kitchen advice and practical tips from personal experiences. As a mom of two, Tara understands the value of time. She crafts articles that enhance your cooking skills and free up time for what matters most—like family moments.

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9 thoughts on “Coffee Maker Mold Is Making You Sick!”

  1. I’ve been very sick with all these symptoms. Recently my husband took apart the coffee maker to fix it and had to blow out the pipes. What came out was chunks of horrid looking stuff. My doctor has ordered all kinds of xrays and tests and nothing shows. In the meantime I’m very ill. Any suggestions for my doctor on what test’s to order.
    Thank you

    • Hi Cat! We’re sorry to hear that you’re not feeling well. We don’t have any recommendations or suggestions for your doctor. Your doctor will be more qualified than us for figuring out the cause of your symptoms. Get well soon!

  2. I have thrown up & had diarrhea at least 7 times since 7:00 tonite with sore legs & chills as well. I drink 3+ cups of coffee each morn. Are these syptoms associated with keurig Brewers?

  3. I had the same symptoms and I am throwing away my keurig machine I am spending my long holiday weekend inside because I decided to have a coffee yesterday and I generally buy it out. I can not believe it this is what caused my stomach pains, and indigestion. There should be a class action law suit to keurig for not warning people of this hazard. gross.

  4. I had a cup of coffee at 2pm and at 2am I got hit with stomach cramps, the runs and indigestion. Do you have any ideal how long they will last or should I seek medical help?

    • Hi David,

      It may or may not be related to the coffee you drank. We can’t offer medical advice, but if you are concerned about your state of health then you should definitely contact your physician.

  5. I just want to mention that the article seems to confuse bacteria with mold. They are NOT the same thing. The second photo shows mold, not bacteria, probably after at least two or three days old.
    Both can be harmful, depending on which species is growing; remember, spores are NOT from bacteria, but from mold, which is a fungus-kind microorganism, and mold can grow in bread, cheese, flour, etc. Some are beneficial, like in cheese, others are harmful. As for the fecal bacteria, it is called Escherichia coli, and some strains of E. coli can cause serious infections; it usually comes from contaminated water from animal or human excrement. I guess that we should boil our drinking water as a precaution.
    I use an italian type of coffee maker (the one to put on top of the stove), made of stainless steel, which is easy to disassemble and to wash; sometimes if I forget to wash it, mold will grow in the water in the reservoir within two or three days; it is a very tough microorganism, as spores contained in the coffee grain can survive.

  6. I have had diarrhea and bloating for three years and have been to every doctor from my PCP to a Psychiatrist. Throw in a GI guy too. I’ve had every test these doctors could order – blood, stool, CT scan, colonoscopy, etc.

    At times I couldn’t even leave the house. I’ve soiled the bed and my skivvies. It was like being on the edge of having the flu 24/7. My quality of life was lost.

    One day I discovered a pellicle floating in my coffee maker water reservoir, so I cleaned the reservoir with bleach first, then vinegar. Brown mold was abundant. After the cleaning and drinking coffee, I felt better, but not completely.

    I made some home brew beer a couple weeks later and noticed something growing in the faucet leading from the keg. Took the faucet apart, cleaned the mold off with bleach, and have had “normal” BMs since. No bloating, sick feeling, NOTHING!!!

    I feel great now…..PLEASE CLEAN YOUR COFFEE MAKER (and ANY other place mold can grow that you would ingest it!!!!


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