Your coffee maker probably gets more love than just about any other appliance in your kitchen—but have you ever thought about cleaning it?
How to clean a coffee maker might not be something you’ve ever wondered, but there are some pretty good reasons to do so. For one, there’s the hygiene issue: The warm, moist environment can be a breeding ground for germs like bacteria or mold.
“We see growth from that residual moisture,” Kelly Reynolds, Ph.D., a University of Arizona professor of public health specializing in water quality, food safety, and disease transmission, tells SELF. “There are a lot of little crevices in a coffee maker that stay moist for a long time.”
Around 50% of auto-drip coffee maker reservoirs (the place where you pour the water) harbor yeast and mold, a 2011 National Science Foundation (NSF) study found. (While the study was small, the results are not exactly surprising.) If you have a mold allergy or asthma, those microbes can irritate your airways, says Reynolds.
You can have mold even if the inside of your coffee maker looks pretty clean. “Mold spores are microscopic,” Reynolds says. “Once you actually see them, you’ve got millions of spores growing.” Studies, including that NSF one, have also shown that auto-drip coffee makers can also occasionally harbor bacteria that have the potential to cause food poisoning, like salmonella and E. coli.
While there’s not much data on how many people have actually experienced an allergy or asthma attack or a bout of food poisoning from their auto-drip, the risk is probably pretty small, says Reynolds. “Because coffee gets boiled, a lot of the microbes are killed off,” she explains. Still, if your mold and bacteria counts are very high, boiling may not be enough to bring the counts down enough, she says.
What’s more likely is that a not-so-clean coffee maker could mess with the taste of your favorite brew.
“Over time, brewed coffee leaves behind coffee oils, which can go rancid and taste bad. When the residue isn’t removed regularly, it will make your coffee taste increasingly bitter,” Grace McCutchan, a coffee roaster at Red Rooster Coffee Roaster & Café in Floyd, Virginia, tells SELF. That means you might not be getting your money’s worth on those awesome beans you splurged on.
Plus, you might actually become acclimated to the acrid, stale taste due to the buildup of leftover oils. “It could definitely taste off without you even knowing it,” McCutchan says. In fact, many casual coffee drinkers may actually just get used to that flavor and think it’s part of the coffee.
How to clean your coffee maker
So yes, you do need to clean your coffee maker. The good news, though, is that it isn’t a situation that calls for hours of scrubbing. In fact, McCutchan’s favorite DIY method is mostly a leave-it-and-forget-it type of cleaning:
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Fill your reservoir with 1 part white vinegar to 2 parts water. (For a 12-cup brewer, that’s 4 cups white vinegar and 8 cups water.) “The vinegar cuts through grime and kills bacteria,” she explains.
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Let the mixture sit in the reservoir for 10 minutes. Hit brew, then let the hot brewed mixture sit in the coffee pot for 10 minutes. That gives the vinegar time to hit both the reservoir and the pot.
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Rinse the pot, then perform two brew cycles with just water to get rid of any lingering vinegary taste.