You Might Not Have to Wash Your Office Coffee Cup After All

We’ve all been guilty of it at some point: using yesterday’s unwashed coffee cup for the next morning’s cup of coffee.

Naturally, this is especially the case at the office.

But that lazy coffee-drinking coworker might be on to something.

In fact, he or she may actually be less susceptible to nasty bacteria.

Here’s the thing, you know that sponge in your office that’s been sitting there for longer than you can remember? Well, it’s full of so much harmful bacteria – think, the remnants of every coworker’s lunch – that it may just be the grossest thing in the office when it comes to germs.


Meaning, the little leftover coffee residue is actually better for you than washing it most of the time.

The Wall Street Journal’s Heidi Mitchell recently interviewed Jeffrey Starke, a pediatrics professor at Baylor College of Medicine.

While leaving cream or sugar in your coffee cup can lead to mould, Starke said that leaving minimal residue in your cup, then refilling it the next day is harmless.

“If I went and cultured the average unwashed coffee cup, of course, I’m going to find germs,” said Starke. “But remember, a vast majority came from the person who used the cup.”


Because most bacteria die shortly after leaving the body, you could drink from your coffee cup in the midst of a brutal cold and not re-infect yourself when you return from your sick day.

He reinforced the point that the sponge in the coffee or lunchroom probably has the most bacteria of anything in the office.

So, as long as it’s free of days-old cream or sugar, don’t worry so much about your coffee cup.