Does flushing the toilet with the lid down really stop germs from spewing across your bathroom? A study says no

Putting the toilet seat down prior to flushing does little to stop virus particles from contaminating the area around it, new research shows.

Many people labor under the belief that putting the lid down stands in the way of aerosolized germs shooting up to five feet away from the toilet, spreading pathogens to floors, walls, and sink.

But researchers from the University of Arizona and Reckitt Benckiser – the maker of Lysol – concluded that this is untrue, and in fact, the only way to truly prevent the spread of viral pathogens was to disinfect the toilet and scrub brush.

Earlier studies have shown that a closed lid can mitigate the spread of bacteria from the flush, but the latest research is an attempt to see if the same goes for smaller viral particles.

Researchers tested for viral particles in a residential and a public toilet in an office building.

They put a virus not able to infect humans into the toilet, flushed, and, after a minute, used a sponge to swab restroom surfaces, including the spots in front and either side of the toilet, as well as the surrounding walls.

Researchers observed no statistically significant difference in the quantity of virus retrieved from bathroom surfaces, whether the toilet lid was up or down, or whether the toilet or the nearby floor was examined.

Minimal viral contamination was noted on the surrounding walls in both lid up and lid down scenarios, with the most contaminated surface being the toilet seat. 

Comparable patterns of contamination were also identified in public toilets.

Closing the lid before flushing led to elevated contamination levels to the left and in front of the toilet but a minor reduction in contamination to the right of the toilet, according to the researchers.

Toilet bowls subjected to cleaning with both a brush and a disinfectant, specifically hydrochloric acid, exhibited lower contamination compared to those cleaned solely with a brush. 

The study further indicated that employing a disinfectant during bowl cleaning contributed to decreased contamination on adjacent surfaces, such as the restroom floor and the toilet brush caddy.

Cleaning with a disinfectant and brush reduced viral contamination on the toilet by more than 99.99 percent and on the brush by over 97 percent.

Dr Charles P. Gerba, lead author and a professor of virology at the University of Arizona, said: ‘With results showing that closing toilet lids has no meaningful impact on preventing the spread of viral particles, our study highlights the importance of regular disinfection of toilets to reduce contamination and prevent the spread of viruses.’

Their research was published in the American Journal of Infection Control.