How Often Should I Wash My Office Coffee Mug?

The humble mug is one of the most important parts of an office. It’s there to hold your coffee when you need that boost first thing in the morning , to show off your personality with a funky pattern or amusing joke, or to hold on to for warmth when someone else is controlling the aircon. It cares for you – but are you giving it the love and attention it truly deserves? In other words, are you giving it a regular wash?

Take a look at Reddit and you’ll soon find that people take a lot of different approaches to cleaning their coffee mugs; some wash it every day, others just give it a quick rinse between uses and some, well, they just like to let all the flavors of every drink they’ve ever had mix together.

A survey of over 2000 British adults had similar findings. Those who cleaned their office mugs after every single use were in the majority – at least if they were telling the truth – but there were plenty who went multiple uses without giving it a good scrub and 3 percent who confessed to never washing it at all (although Brits are even worse when it comes to washing towels ).

While that could be a problem if some delightfully fluffy mold starts to grow, the bacteria that lurk within an unwashed mug aren’t necessarily a problem.

“If I went and cultured the average unwashed coffee cup, of course I’m going to find germs,” Dr Jeffrey Starke, an infectious disease specialist, told the Wall Street Journal . “But remember the vast majority came from the person who used the cup.”

So what about the germs that don’t come from the mug’s owner? Dr Charles Gerba, a professor of microbiology, environmental sciences, and public health at the University of Arizona, told LifeHacker that “around 90% of most office coffee mugs harbor dangerous germs, and 20% of those carry fecal bacteria."

Unless someone in the office is taking inspiration from Andy Samberg’s character’s antics in the “ Like A Boss ” music video, both Starke and Gerba suggest that any of the nastier bacteria that could be lurking in your mug might actually come from… cleaning it.

The sponge in the break room probably has the highest bacteria count of anything in the office,” said Starke, speaking to the Wall Street Journal. That would make a lot of sense – it touches a lot of different stuff, sits there damp, and probably isn’t replaced all that often. As Starke quite accurately concluded: “Most people would call that gross.”

With that, it might seem better to leave it unwashed, though plenty of people would also be grossed out by that prospect. In that case, experts recommend making use of paper towels, alongside soap and hot water, to scrub your office mug as well as to dry it. Better still, take it home and pop it in the dishwasher if you have one.

As for how often you should do so, some would say after every use – but we won’t tell if you don’t.