The Truth About Public Toilets, According to Science

If you’re a parent, or you live with a long-term health condition that means you need the loo quickly and often, you’ve probably already worked out which public toilets nearby are reasonably reliable.

Even so, there are moments when you have no alternative but to use a cubicle that looks as though it hasn’t had a proper clean for ages. In that situation, do you grit your teeth and sit on the toilet seat?

And if the seat looks “not too bad”, is it still worth worrying that sitting down could expose you to germs and make you ill?

What ends up in public toilets?

A healthy adult produces more than 1 litre of urine and over 100 grams of poo every day. Along with that, everyone sheds bacteria and viruses in their faeces (poo) and urine, and some of these inevitably end up in the toilet environment.

Some people - particularly those with diarrhoea - can shed larger amounts of more harmful microbes (both bacteria and viruses) when they use the loo.

Because of high footfall and inconsistent cleaning, public toilets can effectively become a “microbial soup”, especially where many people use the facilities and cleaning doesn’t happen as frequently as it should.

Public toilet seats: what germs have been found?

Researchers have detected a wide range of microbes on toilet seats and nearby surfaces in public toilets, including:

• Gut bacteria and viruses, such as E. coli, Klebsiella and Enterococcus, as well as viruses like norovirus and rotavirus. These can lead to gastroenteritis, often involving bouts of vomiting and diarrhoea.
• Skin bacteria, including Staphylococcus aureus - sometimes even multidrug-resistant S. aureus - plus other bacteria such as Pseudomonas and Acinetobacter. These can cause infections.
• Parasite eggs (worms) carried in poo, as well as single-celled organisms such as protozoa, which can trigger abdominal pain.

On top of that, there’s biofilm: a build-up of mixed germs that can accumulate under toilet rims and on different surfaces.

Are toilet seats the dirtiest surface in public toilets?

Not usually. A recent study found that public toilet seats often carry fewer microbes than other parts of public toilets, including door handles, tap handles, and flush levers. These are high-touch areas and are frequently handled with unwashed hands.

In busy locations, public toilets can be used hundreds or even thousands of times a week. Some are cleaned regularly, while others - such as those in parks or at bus stations - may be cleaned only once a day, or even less. When cleaning is infrequent, germs can build up rapidly. Typical warning signs that a toilet hasn’t been cleaned include a strong smell of urine, dirty floors, and whatever grime is plainly visible.

However, the biggest issue isn’t only the act of sitting down - it’s what happens when the toilet is flushed. If you flush a toilet without a lid, a toilet plume can blast tiny droplets into the air. Those droplets may contain bacteria and viruses from the bowl and can travel up to 2 metres.

Hand dryers that force air across the room can also spread germs when people haven’t washed properly. In other words, as well as drying your hands, you may also be blowing microbes over yourself, other people, and the bathroom.

How do germs spread in public toilets?

You can come into contact with germs in public toilets through several routes:

• Skin contact. Sitting on a dirty seat or touching handles can transfer bacteria. Healthy skin is a strong barrier, but cuts and scrapes can allow germs to get in.
• Touching your face. If you touch your eyes or mouth - or handle food - before washing your hands after using the toilet, germs can enter your body.
• Breathing them in. In small or crowded bathrooms, you may inhale tiny particles from toilet plumes or hand dryers.
• Toilet water splash. Germs can remain in the water even after several flushes.

It’s also worth remembering that your personal risk isn’t the same every day. If you’re unwell, immunocompromised, caring for very young children, or supporting someone with a chronic condition, everyday hygiene steps in public toilets matter more - not because the seat is uniquely dangerous, but because there are more opportunities for hand-to-face transfer.

Another practical factor is the layout and maintenance of the facility. Cubicles with lidded toilets, adequate soap, and paper towels make it easier to reduce exposure to toilet plume and improve hand hygiene; poorly stocked facilities do the opposite.

What can you do to stay safe?

These straightforward steps can reduce your exposure to germs:

• Use toilet seat covers or lay toilet paper on the seat before sitting down.
• If there’s a lid, wipe it before use with an alcohol wipe and close it before flushing to limit exposure to a toilet plume. (Be aware this won’t stop spread completely.)
• Wash your hands thoroughly for at least 20 seconds with soap and water.
• Carry hand sanitiser or antibacterial wipes to clean your hands afterwards if there’s no soap available.
• Avoid hand dryers where possible, as they can spread germs; use paper towels instead.
• Clean and sanitise your phone regularly, and don’t use it in the toilet. Phones can easily pick up and carry bacteria, especially when used in bathrooms.
• Wipe down baby changing areas before and after use, and always wash or sanitise your hands.

So, is it safe to sit on public toilet seats?

For most healthy people, yes - sitting on a public toilet seat is generally low risk. If it helps you feel more comfortable, you can wipe the seat with an alcohol wipe or use a toilet seat cover.

Most infections linked to public toilets aren’t picked up from the seat itself. They’re more commonly associated with dirty hands, door handles, toilet plumes, and phones used in bathrooms.

Rather than focusing on whether to sit, prioritise hygiene: wash your hands, choose paper towels over dryers, clean the seat if needed, and keep your phone clean.

And please don’t hover over the toilet. Hovering tightens the pelvic floor, which can make it harder to fully empty the bladder - and it also increases the chance you’ll accidentally spray bodily fluids.

Lotti Tajouri, Associate Professor, Genomics and Molecular Biology; Biomedical Sciences, Bond University

This article is republished from The Conversation under a Creative Commons licence.