"Our jaws dropped": Dangerous germs are stirred up when flushing the toilet
Created: 01/08/2023 07:38
By: Kilian Bäuml
Researchers visualize what happens when you flush the toilet.
That small particles get into the air, they are now captured on pictures.
Kassel – Anyone who thought that the residues in the toilet are simply flushed away with the flush is wrong: Every time the toilet is flushed, germs are released into the air.
Researchers have now captured this process in pictures, making it visible to everyone.
The science magazine nature.com
published their results
The researchers observed that the particles were transported up to 1.5 meters from the toilet within eight seconds.
The flushing creates tiny droplets, so-called aerosols.
These are so tiny they float in the air.
From the toilet into the air: This is how researchers determine what happens when you flush
A flow is created in the toilet by the water entering the flush.
It is accompanied by typical noises, from which the researchers deduced that the mud is energetic and turbulent.
The researchers used a measuring device to record the noise and the sound pressure level in the vicinity of the pool.
To make the process visible, the researchers illuminated the aerosols with a continuous laser and recorded them with a camera.
The pictures show how the particles spread out of the toilet during and after the flush.
"The first time we did it, our jaws dropped," John Crimaldi, one of the study's authors and a professor of engineering at the University of Colorado, told
With every flush, particles from the toilet are released into the air.
© John Crimaldi, University of Colorado
After flushing the toilet: Airborne germs can be dangerous
The particles from the toilet contain faecal germs and dangerous pathogens such as corona and norovirus.
These pathogens have been shown to remain on surfaces for several days.
They can be found in the bathroom and even on the toothbrush.
So far, however, the researchers know very little about the spatio-temporal development of these aerosols.
How high the risk is depends on various factors.
A closed toilet lid, for example, reduces the risk but does not completely prevent it.
In some public facilities there is also no possibility to close the toilet lid.
"Public toilets can be tight spaces with wildly fluctuating air exchange rates," said Crimaldi.
That is why it is important to clean the toilet properly.
Germs from toilet flushing in the air: risk difficult to prove
How the germs spread also depends on the behavior of the toilet user.
This makes it difficult to assess the risks posed by the germs.
"In most cases, it's incredibly difficult to prove the nature of the transmission, let alone the source," Joshua Santarpia told
Santarpia is a microbiologist at the University of Nebraska Medical Center, studying aerosol transmission of disease.
The scientist believes it is likely that diseases are often transmitted through the particles in the air in toilets.
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Fancy a voyage of discovery?
With their results, the researchers want to sensitize society.
The shape and design of toilets have changed little over the past few decades, so it's time to adapt them to specific circumstances, Crimaldi said.
This is also possible elsewhere, such as on airplanes or in areas where there is no running water.