How Bad Is It Really to Not Close the Toilet Lid When You Flush?

It's cold and flu season, so chances are you're seeing everyday objects like doorknob handles, shared keyboards and shopping carts as serious germ vectors. But what about ... your toilet?

Back in the early days of COVID-19, experts warned that the virus could potentially spread from flushing without closing the toilet lid. As in, germ-containing fecal matter could get sprayed upwards from the bowl while flushing, splashing invisible bits of virus into the air and onto nearby surfaces, just waiting to infect someone nearby.

But the fear of toilet plume (that's scientist speak for germy mist getting flung around the bathroom via flushing with an open toilet lid) has been around well before 2020. In fact, microbiologists have been warning about the phenomenon since the 1970s. But do you ‌actually‌ need to worry about this? And are you putting yourself and others at risk if you forget to close the lid?

The answer might surprise you.

You may not know it, but not all of the water in the toilet bowl goes down the pipe when you flush.

Microscopic droplets are also sprayed into the air, many of which contain bacteria from fecal matter, according to Nikhil Bhayani, MD, FIDSA, an infectious disease physician with Texas Health Resources in Bedford, Texas. Experts call these infectious viral droplets aerosols.

The amount of toilet plume aerosols that end up in the air — and how far they travel — depends on all kinds of factors (like how powerful the toilet flush is, how germy the toilet bowl water is and so on). But the stuff can definitely get around. Bacteria from toilet plume has been found 10 inches above some toilet seats and continued to stick around on surfaces as long as 90 minutes after flushing, found one January 2012 study published in ‌The Journal of Hospital Infection‌.

And by surfaces, we're not just talking about the toilet seat itself. "The particles could land on a bathroom vanity or a toothbrush. And if the space isn't cleaned regularly, this could possibly cause someone to become ill," Dr. Bhayani says.

If you want to take a break from reading to go and disinfect your bathroom, we'll be waiting right here.

‌Seriously? I've never actually heard of someone getting sick from flushing a toilet‌, you might be thinking. But the thing is, there are plenty of instances where people can't identify who or what caused them to get a cold, the flu or another infection. And lots of viruses live in our poop. So it's possible we're catching bugs from the toilet without realizing it.

Case in point: Norovirus, which causes run-of-the-mill stomach bugs, is found in the feces and vomit of infected people. So it's pretty likely that cases are transmitted via toilet plume aerosols, concluded researchers writing in a March 2013 review published in the ‌American Journal of Infection Control‌. Same goes for bugs like Salmonella, Shigella, E. coli, C. difficile and SARS, the review found.

And those warnings about COVID-19? Yup, it's possible to catch that from toilet plume too, according to an October 2021 study published in the ‌Journal of Environmental Chemical Engineering‌.

By now you're (hopefully) convinced to just close that lid before you flush the toilet. But what about when you're in a public bathroom stall? Not only do the toilets rarely have lids, but an April 2022 ‌Journal of Occupational and Environmental Hygiene‌ study demonstrated that industrial toilets, which are often used in public settings, can generate up to 12 times more toilet plume compared to your average home porcelain throne.

It would be hard to avoid that kind of mist unless you're wearing, say, a gas mask. (Unless you just swear off public restrooms altogether, which, after reading this, you just might want to do.) But a few commonsense steps can help reduce your exposure.

"Don't lean over the bowl after flushing, stay back and wash your hands with soap and water immediately afterwards," Dr. Bhayani says. We might also add: Get out of that stall ASAP.

Science shows that not closing the lid when you flush really can send illness-causing germs all over the place. So if your toilet has a topper, place it down firmly before you flush. (Keep these other unconventional illness-preventing tips in mind too.) You won't keep every single germ from escaping. But according to Dr. Bhayani, you'll slash the number of aerosols that make it into the air by at least half.