What Comes Up When You Flush

With the press of a handle and a powerful whoosh of water, toilets send waste far away from humans and down into the sewer system. But new research shows – in surprising detail – just how much waste they also spew into the air, potentially spreading contagious diseases in the process. 

 

Scientists have known for decades that, when flushed, toilets expel wee particles of water, urine, feces and, at times, dangerous pathogens that are invisible to the naked eye. 

 

But researchers haven’t been able to see the airborne particles, nor understand how and where they spread. 

 

Researchers at the University of Colorado Boulder wondered if they could use lasers to visualize this aerosol plume and measure the trajectory and speed of the toilet-borne particles. They set up green laser beams over a commercial toilet without a lid, positioned two cameras a few feet away, dimmed the lights and flushed. The lasers illuminated the tiny particles ejected by the toilet, allowing the scientists’ eyes and the cameras to clearly see the resulting spray.

 

“If it’s something you can't see, it’s easy to pretend it doesn’t exist”, says study co-author John Crimaldi, an engineer at the University of Colorado Boulder, in a statement. “But once you see these videos, you’re never going to think about a toilet flush the same way again”.

 

During the experiment, airborne particles ejected from the toilet traveled at speeds of up to 6.6 feet per second and reached 4.9 feet above the toilet within eight seconds, the scientists found. 

 

And, once airborne, smaller particles measuring less than 5 microns hung in the air for more than a minute. 

 

Note: The toilet they used in the study was brand new, clean and filled only with tap water, and the researchers write that the presence of fecal matter and toilet paper could affect the trajectory of the aerosol plume. They also performed their flushing experiments in a ventilated laboratory without any partitions and noted that the results may be different in a public restroom with stalls. 

 

Celtic are seven points away from retaining the Scottish Premiership when they triumphed 4-1 after yesterday’s first-half goal blitz against relegation-threatened Kilmarnock. 

 

The green-and-white-striped side were already four up in just twenty-seven minutes after Kyogo Furuhashi (7) swept them in front with ease, Daizen Maeda (12) headed a quick second and Matt O'Riley (18, 27) struck twice.

 

 

 

 

 

 

 

 

 

 

 

 

The Killies, however, did manage to get one back in the forty-fifth minute – but the damage had all been done.

 

Anyway, Celtic now have a 12-point advantage over Rangers and, with a vastly superior goal difference, they effectively need two more wins from six games to clinch back-to-back titles.