4 telltale signs there's mold lurking in your coffee maker – it can grow in as little as 24 hours, coffee and cleaning pros warn

Mold is an unwelcome visitor in any part of your home, but mold in a coffee maker is not only bad news for the taste of your coffee but your respiratory, digestive and skin health too.

Visible signs of mold in your coffee maker are of course, easy to spot, but did you know that in most cases, the mold is more subtle, fast growing and easy to miss? Our coffee and cleaning experts reveal why it grows, the four telltale signs your machine has it, and how to clean your coffee maker's hidden mold with ease.

Why does mold grow in coffee makers?

Finding mold in even the best coffee maker is very common. According to a study by the National Sanitation Foundation, 50% of household coffee maker reservoirs have mold or yeast growing in them.

'The reservoir and tubing are where mold is most likely to grow', confirms Eric Gantz, Co-Founder of Verena Street Coffee who has worked with coffee makers for the past 15 years.

Unsurprisingly, these are the parts where mold is most likely to grow since they’re constantly wet. In the case of a reservoir, you often have standing water and depending on how often you use your coffee maker, this might not be replaced for over a week or more.

Your coffee maker also is a nutrient-rich environment for mold spores, which creates the perfect breeding ground.

Michael Rubino a mold and air quality expert and founder of HomeCleanse, says ‘coffee grounds, mineral buildup, skin cells, and other organic matter' combine with ‘other factors such as high humidity, spills, pooled water, lack of cleaning, and faulty equipment’ for a perfect environment where mold can begin growing in as little as 24-48 hours.

Don't wait for the classic green mold spots to appear in your coffee maker reservoir before taking action. Here's what to watch out for:

1. Visible growth

If you’re familiar with the signs of mold in your home, don’t assume it will look the same in or on your coffee maker. As Rubino points out, ‘Mold comes in a vast array of colors, shapes, and textures, reflecting the diversity of mold species.’

There are many common types of household mold, and you may be used to the look of some of them more than others, such as when you've had to get rid of black mold, clean 'pink' mold, or when comparing mold vs mildew.

Mold growth in coffee makers can look green, blue, brown, black, or even red and it can be fuzzy or slimy. Rubino adds, ‘If you notice any unusual or unidentifiable growth inside your coffee maker, it’s a strong indication of mold contamination.’

2. Unpleasant smells

Another telltale sign of mold is an earthy odor. If the coffee station of your home smells musty, even intermittently, pay attention to it. You may notice an unpleasant damp whiff well before any visible contamination.

Rubino says this is because the mold ‘may be hidden within hard-to-access parts of the coffee maker, such as the tubing, or the colony might still be too small to detect visually’, according to Rubino.

If you're nose isn't particularly sensitive, don't worry. The golden rule is that your coffee maker really shouldn't smell of anything. If you’re greeted by a whiff from an empty coffee maker before your coffee is even done, you likely have a mold problem.

3. Your coffee no longer tastes 'right' or as good as before

This is one of the most annoying potential issues with having mold in your coffee maker as it can wreak havoc on the taste of your quality, or favorite coffee.

Depending on whether you are a coffee connoisseur or only drink it occasionally, you may not notice a moldy taste for a while. However, Rubino recommends paying attention to ‘an unusual or off-putting flavor, particularly one that mirrors a musty or earthy smell.’

Although coffee naturally has a bitter taste, it should be bitter in a pleasant way. If you like a strong, dark roast, you may not notice the moldy aftertaste for some time. But if you are struggling to finish your morning cup because it tastes sour or just ‘off’, it’s time to learn how to clean your coffee maker.

4. Subtle or worsening health symptoms

Rubino admits, ‘Sometimes, mold contamination is neither visible nor detectable by smell, making it more challenging to identify.’ In that case, you need to pay close attention to any unusual or worsening health issues that you might be experiencing after drinking your coffee.

Only you know how coffee normally makes you feel. Do you typically experience an uplift in mood and improved digestion after drinking it? If you haven’t changed your intake amount but are suddenly struggling with digestive, respiratory, or skin issues such as itching or rashes, mold in your coffee maker may be the culprit.

Some people believe that it’s actually mold myotoxins found in the coffee itself that can make you sick. While it is true that coffee contains mycotoxins produced by mold, the amounts are so tiny that they do not pose health risks.

A study published in the Journal of Food Science found no evidence to suggest these are acutely toxic in humans from coffee consumption, and there's a 'low severity and likelihood of risk'.

The same toxins are actually found in nearly all foods and even in human breast milk, so you really shouldn’t worry about them being present in your pack, pods, freeze dried or instant coffee. It doesn't matter which type of coffee you prefer: Keurig, espresso, Turkish coffee, or some other type. They're all safe to consume.

Mold in your coffee maker, on the other hand, could eventually establish a colony, and that may give you the unpleasant symptoms mentioned above.

How to get rid of mold in your coffee maker

Cleaning your coffee maker regularly is the only way to ensure it’s not growing mold. Cleaning with vinegar is a favored DIY solution, although Eric Ganz prefers store-bought coffee descalers, available at Amazon for instance: ‘They’re specifically designed for coffee makers, break down buildup more effectively, and won’t leave behind that vinegar smell or taste.’

Does vinegar kill mold? Absolutely it does. But you may find that descaling tablets or liquids have a slight edge in getting your coffee maker cleaner overall.

Professional cleaner and operations manager at Spekless, Karina Toner advises these steps to remove mold from your coffee maker:

• Take it apart and inspect – Remove all detachable parts (carafe, filter basket, water reservoir) and check for visible mold or slime buildup.
• Rinse with hot water – Rinse all removable parts under hot water, this helps loosen any buildup before deep cleaning.
• White vinegar solution – Fill the water reservoir with a 1:1 mixture of white vinegar and water to kill mold and bacteria.
• Run a brew cycle – Start a brew cycle without coffee grounds, letting the vinegar solution run through the machine.
• Pause for soaking – Halfway through, turn off the machine and let the vinegar sit in the machine for 30 minutes. This helps break down mold even further.
• Complete the cycle – Turn the machine back on and allow the cycle to finish.
• Flush with clean water – Run two or three full cycles with fresh water to remove any vinegar taste or residue.
• Scrub removable parts – Use a soft brush or sponge with dish soap to clean all parts, paying extra attention to crevices.
• Dry thoroughly – Mold thrives in moisture, so dry all components completely before reassembling.
• Prevent future mold – Empty the reservoir after use, clean weekly, and leave the lid open to improve airflow.

Given the statistics, it is highly likely there is mold in your coffee maker if you haven't cleaned it in a while. Fortunately, there's no need to panic: adopt a regular cleaning routine, and the mold will be gone.

If you're big on clean living, delve into the best non toxic coffee makers, tried, tested and rated by our experienced kitchen team.