- Scientists say flushing the toilet can spread a lot of bacteria and viruses
- Find out whether it's best to leave the lid on top or down to reduce contamination.
Flushing the toilet may be more difficult than you think.
According to scientists, flushing releases a “toilet plume” made up of tiny water droplets that travel through the air and spread over every surface in your bathroom.
But can closing the lid protect you from these droplets?
Unfortunately, scientists at the University of Arizona say there's really no difference whether the lid is on top or on the bottom.
Instead, researchers say regularly cleaning the bowl with a disinfectant will remove the worst germs and allow it to flush safely no matter where the lid is.
Since the 1950s, it has been well known that flushing a toilet causes the feces, toilet water, and whatever else in the toilet bowl to explode.
But it also contains substances you can't see, and scientists say a “toilet plume” contains droplets small enough to form an invisible aerosol mist.
Previous research from the University of Colorado used green light and lasers to show that these plumes can fly up to 4.9 feet above toilets within eight seconds.
Even more concerning is that these aerosols can carry bacteria and viruses around the bathroom in the air currents, covering all surfaces and people there.
This can lead to the spread of diseases such as E. coli, norovirus, and even Covid 19.
Conventional wisdom recommends closing the lid to contain the spray, as this poses a risk of infection, especially for hospital wards and immunocompromised patients.
However, as the researchers point out in their paper, there is no real scientific basis for this.
In a paper published in 2006, they stated: American Journal of Infection Control: “The potential benefit of closing the toilet lid when flushing to reduce viral contamination of toilet surfaces has not been empirically proven.”
To find out more, the researchers inoculated public and private toilets with samples of MS2 bacteria as a model for E. coli.
They then flushed the toilet and after one minute took samples from various surfaces around the bathroom.
These samples were taken to a laboratory to determine how contaminated they were.
What was surprising was that there was no statistically significant difference between closing and not closing the lid.
The researchers found that samples taken from around the toilet appeared to be equally contaminated with MS2, regardless of whether the lid was up or down.
Instead, the researchers found evidence that closing the lid likely changed the trajectory of the plume, causing it to descend toward the floor instead of going straight 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 both sides.
However, the toilet lid itself seemed to remain oddly clean.
“Surprisingly, MS2 contamination at the bottom or top of the toilet lid was consistently low, regardless of the lid's position before flushing,” the researchers wrote.
The public toilets studied were found to be more consistently contaminated than domestic toilets because the lids did not close.
However, researchers suggest that this is likely due to the increased flow of water into the toilet bowl when flushing in public toilets.
But there's no need to fear flushing the toilet just yet, because researchers believe they have a solution.
Scientists tested how germs spread during routine toilet cleaning with and without disinfectants.
They found that cleaning with a brush alone spreads MS2 bacteria to the brush, toilet brush caddy, and parts of its surroundings.
However, adding disinfectant along with vigorous brushing reduced toilet water contamination by 99.99 percent compared to brushing alone.
Adding Lysol disinfectant to the bowl before flushing resulted in a statistically significant reduction in contamination of brushes used to clean toilets.
Although using disinfectant did not prevent aerosolized bacteria from spreading around the bathroom, it did significantly reduce the amount of bacteria remaining in the bowl.
This is important because researchers note that bacteria can remain in the toilet no matter how many times you flush it.
For example, if you share a toilet with someone who has norovirus, you can spread the virus by flushing, even if you don't use the toilet immediately afterwards.
However, given the significant impact of disinfectants on bacteria levels in water, researchers say regularly disinfecting toilets is the best way to minimize this risk.
The use of disinfectants is especially important if a member of your family has a weakened immune system.
The researchers note that the contamination levels found in the study were relatively low, but argue that this indicates flushing is a potential route of infection.
Therefore, they recommend “regularly disinfecting all toilet surfaces after brushing teeth in the toilet and/or using disinfectants with residual bactericidal activity.”
“Especially if there is someone living in the household who is actively infected with a virus such as norovirus that causes acute gastroenteritis.”
