Legionella and Public Bathrooms: Are They Safe to Use?
In this article, the water safety specialists at Legionella Control International take a look at the potential health risks caused by the generation of aerosols in public bathrooms and whether you should be taking more care when flushing the toilet.
The article focuses on flushing processes in public bathrooms and how this can lead to the aerosolisation of micro-organisms; potentially increasing the risks from Legionnaires’ disease, gastroenteritis-causing norovirus, and most recently COVID-19, especially in areas that are relatively confined, well used, and may suffer from inadequate ventilation.
A version of this story about legionella and the safety of public bathrooms appeared in Legionella Control International’s newsletter. To get it in your inbox, sign up for free here.
Can norovirus, COVID-19, and Legionnaires’ disease be spread by a simple flush?
If ever you’re out and about, chances are you sometimes need to use a public toilet. You may not think too much about it – in and out and on with your day.
Yet a scientific study covering the generation of aerosols in public restrooms, published in March 2021, has shown that infectious diseases can be spread in such locations. The study found that norovirus, COVID-19, and Legionnaires’ disease could be transmitted in such circumstances.
You may believe that if you wash your hands once you’re done and before leaving the room, you’ll be fine. It certainly helps and should always be done, of course. Yet have you ever thought about what’s in the air around you in a public bathroom? Few people have – and yet there could be dangers lurking there too, dangers that are unseen.
While not everyone becomes ill whenever they use a public bathroom, there are enough bacteria spread in aerosols to lead to this outcome in some cases. And the danger area? The toilet – more specifically, flushing the toilet. Studies have indicated that this has the potential to let bacteria into the air.
How dangerous is a flush?
We use toilets to get rid of urine and faeces. Flushing gets rid of them, but it also creates aerosolised biomatter. This can contain microscopic bacteria that can lead to illnesses in humans who inhale or swallow that bacteria. This was observed during the study linked to above.
Now, it would be reasonable to assume that closing the lid of the toilet would see far fewer bacteria dispersed into the immediate atmosphere. The study states that a decrease was indeed seen, but a closed lid didn’t get rid of it entirely. Of course, toilet seats don’t tend to completely close even when down. So, that gives space for bacteria to escape during the flushing process.
Water aerosols from a toilet flush can spray vertically up to five feet, and stay airborne for up to 20 seconds …
So, while putting the seat down before you flush may help, it doesn’t make a huge difference. And in the case of urinals, a lid isn’t an option anyway.
How far do droplets from a toilet flush spread?
Perhaps more surprising – and worrying – is how far those escaping droplets went in the aerosolised matter ejected during the average flush. Particle counters were set up at various heights to determine how far the droplets went during the experiment.
It was determined that aerosols reached five feet into the air at most. Furthermore, they remained there for a few seconds – up to 20 seconds in some instances. As mentioned above, there were fewer droplets involved when the toilet lid was closed, but there were still enough for someone to be infected if they were still in the cubicle.
Again, it is important to remember that not everyone who remains in a cubicle after flushing the toilet is going to be affected by airborne bacteria in aerosols. However, it is clear to see the danger is there.
More information about the experiment
The measurements were taken in a restroom on a US university campus. To make sure all measurements were as accurate as possible, the room was deep cleaned prior to the experiment. Once cleaning was complete, the room remained empty and out of use for 24 hours before the experiment began.
Thoughts about the dangers of airborne bacteria
Of course, in a real-world setting, deep cleaning, and a sealed bathroom before using it would hardly ever happen. Even regular cleaning won’t remove all bacteria and aerosols from the room.
A bathroom used by many people throughout the day is going to pose a much higher risk to every user than a private bathroom. Small cubicles and multiple users will increase aerosols as many cubicles would be used throughout the day. Regular cleaning processes won’t involve cleaning the air – and that’s where the aerosols will be for a certain time.
It is impossible to say how many people may have been infected with norovirus, COVID-19, or indeed Legionnaires’ disease in such circumstances. However, it seems clear that this scenario could occur. Another recent study found high levels of the coronavirus that causes COVID-19 in bathrooms used by COVID-19 patients in hospital.
It also appeared that the bathrooms saw the highest concentration of the virus compared with other areas frequented by the patients. Studies like these clearly cannot be flushed away – there is much more research to be done.
While regular cleaning of any bathroom is obviously a sensible idea, it does not remove the need to flush a toilet after use. And since lowering the lid only partly reduces the number of aerosols in the air, there is only so much we can do to protect ourselves. Until toilet manufacturers come up with a lid that completely seals the space between the toilet and the underside of the lid, preventing any aerosols from escaping during or after the flush, the risk continues to be there.
Leading legionella and water safety specialists
Legionella Control International are experienced legionella and water safety specialists supporting those responsible for the control of waterborne pathogens, including legionella in the workplace. We help businesses protect their workers, customers and others from the dangers caused by water systems, helping them to meet their health and safety obligations in this specialist area.
Through teams of experts we deliver a full range of services including risk assessments for legionella, pseudomonas and other waterborne pathogens. We also offer Authorising Engineer support, compliance auditing, water quality testing, City & Guilds training and other health and safety risk management services that help keep staff and others safe.
If you would like to speak with one of our water safety specialists about improving your risk management processes call us today on 0330 223 36 86 or contact us here …
