Here’s Why You Don’t Need to Wash Your Work Coffee Mug Every Day

A coffee break is a delicious and highly motivating ritual. But do you really have to wash the mug each time? Science has surprising answers.

Coffee-mugMarta Meos/Shutterstock“I love washing dishes,” said no one ever. That’s why it’s tempting, after you finish your coffee, to leave your mug on the counter until tomorrow. That cup of joe is just flavored water, after all—what could go rancid? (Here’s why we call it “joe,” in case you were wondering.)

Adam Possner, MD, of Rockville Concierge Doctors, tells Reader’s Digest that if you’re drinking your coffee black—no milk, no sugar—then there’s not much for “bacteria or other badness to subsist upon,” especially if you leave the cup out to dry between uses. In fact, that’s how Dr. Possner rolls. He drinks his coffee black and doesn’t bother to wash it day-to-day. “I haven’t gotten sick from it,” he says, “…yet.” Nevertheless, his office manager isn’t pleased, and Dr. Possner has often wondered whether washing out the mug might not lead to a better tasting coffee.

Speaking of the office, research from the University of Arizona indicates that when you leave your mug in a communal kitchen (which we imagine is what you have at the office), you’re running the risk of your mug collecting a lot of unwanted bacteria. And not just because your coworkers may mistake your coffee mug for their own, suggests Peter F. Bidey, DO, MSEd. What about the idea that a little extra bacteria could even benefit your overall microflora? Atlanta-based integrative medicine physician Bindiya Gandhi, MD tells Reader’s Digest, “Not washing a coffee mug for days while you continuously reuse it not very hygienic and you could be prone to getting sick from it, including from mold exposure.”

“Bacteria, viruses, and fungi are everywhere,” points out infectious disease specialist, Aileen M. Marty MD, FCAP. “They float in the air and can land in your cup and grow in between the times you use your cup.” And if you add cream or you tend to dunk food in your coffee, you’re providing the perfect environment for microbial life to flourish. “I’ve personally tested coffee cups that are not cleaned daily and found [not just bacteria, but] fungus. This not only can cause infection, it can trigger an allergic reaction.” Think that’s annoying? Try being on the receiving end of one of these office annoyances.

You can get away with not washing your coffee cup between uses if, like Dr. Possner, you drink it black. He says he hasn’t gotten sick from it “yet.” But only if you’re drinking your coffee alone in your own kitchen, sans milk, sans sugar, and not dunking anything into your dark, delicious brew. Here are 11 other ways to make your coffee habit healthier.

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Lauren Cahn
Lauren Cahn is a New York-based writer whose work has appeared regularly on Reader's Digest, The Huffington Post, and a variety of other publications since 2008. She covers life and style, popular culture, law, religion, health, fitness, yoga, entertaining and entertainment. Lauren is also an author of crime fiction; her first full-length manuscript, The Trust Game, was short-listed for the 2017 CLUE Award for emerging talent in the genre of suspense fiction.