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A debate that has raged for many years is if the toilet seat should be left up or down after using the bathroom. Many men say the lid should be left in the up position for convenience, but most women know how inconvenient that can be.

It seems as if there is another reason why this debate needs reconsidering. After all, it isn’t just about convenience or sitting where you shouldn’t, it’s about the air we breathe.

Photo: TikTok/@whatmightgrow

A microbiologist recently brought this to our attention on TikTok. He said: “When you flush your toilet, aerosol is sprayed into the air.”

This video really struck a chord with many people who watched it and it wasn’t long before it went viral.

Photo: TikTok/@whatmightgrow

It also lent itself to asking another question, how much bacteria ends up in the air? It’s bad enough that the water is airborne, but bacteria is an entirely different subject.

The microbiologist, who chose to remain nameless, tested the theory in a public restroom. For the experiment, a high-powered toilet with a strong flush was used.

To make the experiment as legitimate as possible, he left a “number two” behind for good measure. He then placed a petri dish on the back of the toilet, waited 10 minutes, and then flushed.


How much bacteria comes with your toilet flush? I set out to explore this question. #greenscreen #bacteria #toilet #air #timelapse

♬ Bathroom Dance – Hildur Guðnadóttir

A second petri dish was placed on the back of the toilet at the time of the flush.

By comparing the two Petri dishes, he could see how much bacterial growth occurred in each as time went by. If there was bacteria that went airborne at the time of the flush, there would be a difference in the growth.

When he looked into the petri dish left out before flushing the toilet, there was no noteworthy growth of bacteria.

Photo: TikTok/@whatmightgrow

The second dish that was in place when he flushed the toilet, however, showed two circular areas of growth that continue to grow.

In other words, when you flush the toilet, bacteria are released into the air.

The microbiologist was happy with the results of the experiment, but he was not impressed with the amount of bacteria that was growing. He decided to revisit the experiment at another time, using a dirty toilet.

It only took a couple of days before he was back on TikTok.


Replying to @whatmightgrow What bacteria will grow from a bathroom flush when the petri dish is on the toilet seat? #bacteria #clean #toilet #microbiology

♬ Stolen Dance (Instrumental) – Milky Chance

His toilet at home was used as the test subject in the second experiment. He also allowed the bacteria to grow in the Petri dishes for five days, hoping for a better answer.

In looking at the growth of bacteria, he was still not impressed with the numbers. He even admitted to flushing five times during the 10 minutes to ensure that more bacteria would go airborne.

The microbiologist did say that there was crap in the Petri dish but bacterial growth was minimal. To put it in plain English, nobody is surprised at the results.

In the end, he said it appeared not to be as gross as everyone believed and apologize for disappointing us.