As you sink down onto a toilet seat used by hundreds of other people the same day, you might be wondering: how long do pathogens survive in bathrooms?

Once you set foot in a public toilet, it can be impossible to resist the overwhelming feeling of "ick". The sight of urine splattered on the toilet seat and the floor, the pungent scent of somebody else's bodily fluids – it can really slam against your senses. You might open the stall door with your elbow, flush with your foot, or drape the entire seat in toilet paper and execute a squat if you find the whole thing too gross to contemplate.

But can you actually catch diseases from merely sitting on the seat? Or are the elaborate techniques some people use to avoid contact completely unnecessary? Here's what microbiologists have to say.

"Theoretically, yes [you can catch diseases from the toilet seat], but the risk is vanishingly low," says Jill Roberts, a professor of public health and microbiology at the University of South Florida.

Take sexually transmitted diseases (STDs). Most of the bacteria and viruses that can cause them, from gonorrhea to chlamydia, cannot survive for long outside of an organism's body, let alone on a cold, hard surface like a toilet seat.

That's why it's thought that the majority of STDs an only be transmitted via direct contact of the genitalia and exchange of bodily fluids. One would have to be unlucky enough to transfer someone else's fresh bodily fluids immediately from the seat to the genitalia either by hand or toilet paper to be at risk, says Roberts. So, while it's good to be cautious and maintain hygienic practices, such as avoiding toilets that are obviously contaminated, it's not something that should keep you up at night.

"If toilet seats could [easily] transfer STDs, we would see them frequently across all age groups and in people with no history of sexual activity," says Roberts.

Similarly, Roberts says you're unlikely to catch a bloodborne disease from a toilet seat either. For a start, she thinks you'd see – and avoid – somebody's blood if it was on the toilet seat. In any case, it would not easily transmit bloodborne pathogens in the absence of sexual activity or injection with contaminated needles, she says.

It's equally unlikely that you would catch another person's urinary tract infection (UTI) from the toilet seat, says Roberts. You'd only get a UTI if you transmitted faeces from the toilet seat to the urinary tract, but a large amount of faeces would be required for this, says Roberts. It's much more likely that you develop a UTI by wiping your own excrement too close to your genitalia, she adds.

There are some exceptions of longer-lived sexually transmitted diseases, though. Human papilloma viruses (HPV), which cause genital warts, can stick around for up to a week on surfaces, although it depends on several factors. "These viruses are very small and have very stable protein shells that give them a longer 'shelf life' in the environment," says Karen Duus, a professor of microbiology and immunology at Touro University in Nevada.

HPV tends to be resistant to hand sanitisers and requires a concentration of 10% bleach to destroy that tough, protective protein shell, says Duus. Still, these viruses can only make their way into your body if the skin barrier of your genital area is compromised, says Duus, with a rash or a wound, while you're sitting on the toilet. As such, HPV is typically only transmitted via sexual skin-to-skin contact, such as oral, anal, and vaginal sex.

Similarly, in theory, someone with genital herpes who is having a flare-up could shed virus onto a toilet seat, and subsequent users might be at risk if they have broken skin or if they're immunosuppressed, says Daniel Atkinson, a clinical lead for the online healthcare service company Treated.com in the United States. But it's unlikely, says Atkinson.

Draping the toilet seat with paper before sitting on it, or using a toilet-seat cover, might feel like the cleanest way to use a public toilet.

According to one poll by the research group YouGov from 2023, around 63% of Americans sit down when they use a public toilet – but around half of those first line the seat with toilet roll. The same poll found that around 20% of people squat instead.

However, a layer of toilet paper or a toilet cover will likely not protect you from pathogens – they

© BBC