- Flushing spreads “toilet plumes”
- Lid position irrelevant to safety
- Disinfectant significantly reduces bacteria
The act of flushing the toilet could be significantly more disgusting than you might have initially thought.
According to scientific claims, flushing releases tiny particles known as “toilet plumes” that spread through the air and cover every surface within the bathroom.
However, does closing the lid protect against this spray?
Unfortunately, researchers from the University of Arizona have concluded that the position of the lid—whether it is down or up—is irrelevant.
They suggest that regularly disinfecting the bowl with disinfectant will kill the most harmful bacteria and make flushing safe, regardless of the lid’s position.
It has been widely recognised since the 1950s that flushing the toilet results in a substantial release of faeces, toilet water, and any other contents present in the bowl.
However, this includes invisible matter as well; scientists claim that “toilet plumes” consist of tiny droplets that condense into an aerosol vapour that is not visible.
Previous research conducted at the University of Colorado used green light and lasers to show that these plumes can rise 4.9 feet above the toilet in just eight seconds.
An even greater cause for concern is the potential for these aerosols to be carried by air currents throughout the bathroom, contaminating any surfaces or people present with bacteria and viruses.
This could result in the transmission of diseases such as E. coli, norovirus, and COVID-19.
Lid Closure Effect on Plume Spread
To contain the spray and reduce the risk of infection, particularly in hospital settings or for people with compromised immune systems, it is generally advised to close the lid.
However, as the researchers note in their paper, this is not supported by substantial scientific evidence.
In their article published in the American Journal of Infection Control, they state, “No empirical evidence supports the claim that closing the toilet lid during flushing reduces viral contamination of bathroom surfaces.”
To gain further insight, the scientists seeded private and public bathrooms with MS2 bacteriophage samples, which served as a model for E. coli.
After flushing the toilets, samples were collected from various surfaces within the bathroom one minute later.
These samples were then taken to the laboratory, where they were analysed to determine the level of contamination.
Unexpectedly, there was no statistically significant difference between the conditions of lid closure and non-closure.
Regardless of the lid’s position, the samples collected from around the toilet appeared to have been equally contaminated with MS2, according to the researchers’ findings.
Conversely, the researchers found evidence that the plume’s trajectory was likely altered by closing the lid, as it directed towards the floor rather than rising vertically.
In general, the toilet seat exhibited the highest level of contamination, both above and below, followed by the floor around the toilet and the walls on either side.
Nonetheless, the toilet lid seemed remarkably clean.
“Surprisingly, MS2 contamination of the bottom or top of the toilet lid was consistently low, regardless of lid position prior to flushing,” the researchers wrote.
In the study, it was consistently observed that public bathrooms, which lack a cover for closure, had a higher level of contamination than their domestic counterparts.
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However, this is likely due to the higher volume of water entering the toilet bowl during flushing in public bathrooms, according to the researchers.
Nevertheless, flushing your toilet remains safe, as the researchers are optimistic that a solution exists.
The researchers investigated the transmission of bacteria during regular bathroom cleaning, both with and without the use of disinfectant.
It was found that using the brush alone for cleaning transferred MS2 bacteria to the brush, toilet brush caddy, and surrounding areas.
However, when disinfectant was added to vigorous brushing, the contamination of the toilet water was reduced by 99.99% compared to brushing alone.
Disinfecting Reduces Flushing Risks
The contamination of the toilet brush was also significantly reduced when Lysol disinfectant was added to the bowl before flushing.
Although disinfectant did not completely eliminate aerosolised bacteria that were spread during cleaning, it did significantly reduce the amount of bacteria remaining in the bowl.
This is significant because bacteria can persist in the toilet even after multiple flushes, as noted by the researchers.
For instance, if you share a bathroom with someone who has norovirus, flushing could potentially expose you to their illness, even if you do not use the bathroom immediately after them.
However, given the substantial impact that disinfectant has on bacterial levels in water, the researchers assert that consistent bathroom disinfection is the most effective way to mitigate this risk.
It is particularly important to use disinfectant when someone in the household has a compromised immune system.
Despite the relatively low levels of contamination found in this study, the researchers assert that this demonstrates flushing as a potential route of infection.
Therefore, they recommend “consistent disinfection of all bathroom surfaces after brushing the toilet” or “use of a disinfectant that retains residual microbicidal activity.”
This is especially the case when someone in the household is actively infected with a virus that causes acute gastroenteritis, such as norovirus.
