Flushing the toilet can be much more disgusting than you expected.
According to scientists, flushing the toilet emits “toilet plumes” of small droplets that spread through the air to all surfaces in the bathroom.
But can closing the lid keep you safe from this spray?
Unfortunately, scientists at the University of Arizona say it really makes no difference whether the lid is up or down.
Instead, regularly cleaning the container with disinfectant can eliminate the worst bacteria and make flushing safe no matter where the lid is, they say.
Scientists say flushing the toilet can release a plume of aerosolized bacteria and viruses into the air, but is it better to leave the lid open or closed when flushing?
It has been well known since the 1950s that flushing the toilet causes an explosion of fecal matter, toilet water, and whatever else may be in the bowl.
But this includes material you can’t see, as scientists say “toilet plumes” contain droplets so small they form an invisible aerosol mist.
Previous studies from the University of Colorado have used green light and lasers to reveal that these plumes can fly 4.9 feet above the toilet in eight seconds.
What’s even more concerning is that these aerosols can float on air currents and carry bacteria and viruses throughout the bathroom, covering any surfaces and people present.
This can lead to the spread of diseases such as E. Coli, norovirus and even Covid 19.
Because of the risk of infection this creates, especially in hospital wards or for immunocompromised people, prevailing wisdom recommends closing the lid to contain the aerosol.
But as the researchers point out in their article, this has no substantial scientific basis.
They say in their article published in the American Journal of Infection Control: “The potential benefit of closing the toilet lid during flushing to reduce viral contamination of bathroom surfaces has not been empirically demonstrated.”
The researchers seeded a toilet with MS2 bacteria, a model of E. Coli, and took samples from the areas surrounding the toilet one minute after flushing.
To learn more, the researchers seeded a public and private bathroom with samples of the MS2 bacteria as a model for E. Coli.
The toilets were then flushed and, after a minute, samples were taken from various surfaces around the bathroom.
These samples were then transferred to the laboratory and studied to see how contaminated they had become.
What was surprising was that there was no statistically significant difference between closing the lid or not.
The researchers found that samples taken around the toilet appeared to have been equally contaminated with MS2, regardless of whether the lid was facing up or down.
Instead, the researchers found evidence that closing the lid likely changed the column’s trajectory: toward the ground rather than up into the air.
Overall, the toilet seat was the most contaminated area, both above and below, followed by the floor around the toilet and the walls on either side.
However, the toilet lid seemed to remain strangely clean.
Surprisingly, the researchers found that leaving the lid open or closed made no statistically significant difference in the spread of bacteria in the bathroom.
The researchers wrote: “Surprisingly, MS2 contamination of the bottom or top of the toilet lid was consistently low, regardless of the position of the lid before flushing.”
The study’s public toilets, which do not have a locking lid, were found to be consistently more contaminated than domestic toilets.
But the researchers suggest this is probably due to a greater flow of water into the toilet bowl during flushing in public toilets.
But there’s still no reason to fear flushing the toilet, as researchers believe there is a solution.
Scientists tested how bacteria spread during routine bathroom cleaning with and without the use of disinfectant.
They found that cleaning with just the brush spread the MS2 bacteria to the brush, the toilet brush holder, and parts of the surrounding area.
But vigorous brushing, plus adding disinfectant, reduced toilet water contamination by 99.99 percent compared to brushing alone.
Adding Lysol disinfectant to the bowl before flushing also produced statistically significant reductions in contamination from the brush used to clean the toilet.
While the disinfectant didn’t stop cleaning from spreading some aerosolized bacteria around the bathroom, it did significantly reduce the amount of bacteria left in the toilet.
But, as this graph shows, adding disinfectant to the toilet bowl while it was being cleaned led to significant reductions in the number of bacteria in the bowl. It’s important to note that the scale of this graph is logarithmic rather than linear, so the differences may appear less significant than they actually are.
This is important because researchers note that bacteria can remain in the toilet even after multiple flushes.
If you share a bathroom with someone who has norovirus, for example, you could become infected with their illness by flushing the toilet even if you don’t use the bathroom immediately after that person.
However, given the significant effect of disinfectant on bacteria levels in water, researchers say that regularly disinfecting the toilet is the best way to minimize this risk.
The use of disinfectant is especially important when someone in the household has a compromised immune system.
Although the researchers note that the levels of contamination found in this study were relatively low, they maintain that this shows that flushing is a potential route of infection.
Therefore, they recommend “regular disinfection of all bathroom surfaces after brushing and/or the use of a disinfectant that leaves residual microbicidal activity.”
“Particularly when the home is occupied by a person with an active infection with a virus, such as norovirus, which causes acute gastroenteritis.”