To Close or Not to Close
Does closing the toilet lid before flushing keep germs contained to the bowl? Research suggests that there might be more to it.
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Growing up, I was never taught to close the toilet lid before flushing. After moving out, I found out that flushing can disperse small and large water droplets onto toilet seats, floors, walls, and other surfaces more than five feet from the toilet; even my bathroom counter wasn’t safe. Disgusted, I threw out my toothbrush and started closing the lid every time.
Flushing can spread the various pathogens found in wastewater, from E. coli to COVID-19, between people who share the same bathroom. The common understanding is that closing the toilet lid contains toilet germs to the bowl. But this is an assumption not backed by research.
To test if putting the toilet lid down limits the spray of pathogens, Madison P. Goforth and colleagues placed colonies of a model virus in a home toilet. After flushing, they used a sponge stick to collect residues from the bathroom floor and walls, as well as the toilet lid, rim, and seat. The researchers repeated these steps with the lid up and down, cleaning the bathroom and adding new viral colonies to the water between flushes.
The figure above illustrates the viral spread after flushing with the lid open and closed. The arrows show the direction of the spray of aerosolized viruses, called toilet plumes, after flushing. Bathroom surfaces were similarly contaminated with the toilet seat up or down, as water escaped from beneath the closed lid through the gap between the seat and the toilet rim.
The researchers found that cleaning the toilet with a brush and disinfectant almost completely eliminated the viruses on all surfaces, eliminating germs at the source. Scientists often recommend scrubbing the toilet and surrounding area with a cleaning solution at least once a week. The authors suggest that this is a much more effective method of limiting the spread of pathogens than closing the toilet lid.
My housemates and I will likely continue closing the toilet lid before flushing. As long as our toilet bowl is clean and my toothbrush is locked away in my medicine cabinet, I’ll be doing my best to keep our bathroom germ-free.
