Close the lid when flushing the toilet. This video will show you why it’s worth it

Scientists from the University of Colorado at Boulder used a green laser to illuminate an aerosol that was created when a toilet was flushed. When the hatch was open, water droplets shot up into the air. They were lit and photographed as they moved and how far they spread.

When we flush the toilet, we contribute to the release of microscopic water droplets that contain harmful fecal pathogens, including bacteria and viruses that can linger in the toilet bowl even after several flushes. The researchers wrote about their discovery in Scientific Reports.

“If we can’t see something, we pretend it doesn’t exist,” said lead author John Crimaldi. He added, “Once you watch this movie, you will never think of a toilet the same way again.”

Scientists have known for nearly 60 years that unsealed toilet bowls emit aerosols, and previous research has determined just how far that can go. But until now, it’s been a mystery exactly how the aerosol plumes formed, how fast they moved, and how long they stayed in the air.

New videos have revealed that airborne particles travel at two meters per second. This speed allows them to reach up to 1.5 meters above the toilet in eight seconds. “We expected these aerosol particles to kind of float, but they came out like a rocket took off,” Crimaldi said.

Experiment has also shown that particle size can affect how long they stay suspended in the air. While larger droplets tend to settle to surfaces within seconds, the researchers write, smaller particles, less than five microns in diameter, can remain suspended in the air for minutes or longer.

Fecal pathogens include bacteria such as Escherichia coli and Clostridium difficile, as well as noroviruses and adenoviruses, which can cause serious stomach and intestinal problems.

The team hopes the videos will make people aware of the dangers of using public restrooms and may convince building designers to try adding coverings to public restrooms in the future.