How Dirty Are Public Restrooms?

  • By Anna Rothschild
  • Posted 10.22.15
  • NOVA

What is lurking in the bathroom? Find out in this episode of Gross Science

Running Time: 03:00


How Dirty Are Public Restrooms?

Posted: October 22, 2015

Are any public restrooms actually clean?

I’m Anna Rothschild, and this is Gross Science.

OK, so the bad news is that bathrooms, like every other place humans hang out, are crawling with our bacteria—no matter how much we try to clean them.

In one study, researchers disinfected shared restrooms at a university and then sampled them over time. They found that human bacteria can recolonize a bathroom within an hour of it being cleaned. And those microbes can survive for hours after humans have left, too.

So, what’s actually lurking in the bathroom? Well, gut bacteria, which come from people’s feces, turn up on toilet seats. And in women’s rooms, vaginal bacteria show up on the seats, as well. Some toilet flush handles also have soil bacteria on them—probably thanks to germophobes flushing with their feet. (Guilty!)

All that said, your skin provides a great barrier to protect you from most of the microbes hanging out on the toilet itself. But where else in a bathroom might germs be hiding? Well, in one preliminary study (again, in shared college restrooms) researchers found that more than half of toothbrushes had live fecal bacteria in their bristles. The bacteria seem to fly across the room in the spray from toilet flushes.

To top it off, even washing your hands can make a mess. One study found that if you have bacteria left on your hands after you rinse them, a regular warm air dryer can blow them around the bathroom. And jet dryers can scatter germs up to four and a half feet away. That being said, always wash your hands, people! According to the CDC, hand washing is one of the best things we can do to keep from getting sick and spreading disease.

So no, restrooms are never totally clean. But that’s no reason to panic. Some of the bacteria in them might be able to make you sick, but lots of it is completely harmless. And the biggest myths, like being able to catch STDs from toilet seats, are in no way founded in reality. In a strange way, I actually find this kind of comforting. It’s a reminder that we’re always living with germs, whether in a public bathroom or on our couch at home. Still, you probably shouldn’t lick the toilet seat.




Host, Editor, Animator
Anna Rothschild
Elizabeth Preston
DP, Sound
Ceri Riley
Rag Boy
Music Provided by APM
Original Footage
©WGBH Educational Foundation 2015
Monster in Toilet
Band, C. (Producer), & Band, A. (Director).(1988). Ghoulies II [Motion Picture].United States: Empire Pictures, Taryn Productions Inc.
Keep Calm And Wash Your Hand


(used with permission from author)
Squeak Pack/squeak_10
Produced by WGBH for PBS Digital Studios


©WGBH Educational Foundation 2015


Want more info?

If you liked this episode, check out this awesome video by AsapSCIENCE, “Should You Hover or Cover?”:

Bacteria recolonizing the bathroom after cleaning:

Types of bacteria in different parts of the bathroom:

Bacteria on toothbrushes:

Germs and hand dryers:

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