Think closing the toilet lid while flushing keeps icky stuff like viruses inside the toilet?
Think again.
Research has shown that people with COVID-19—even asymptomatic people—“excrete the SARS-CoV-2 virus in fecal matter and other excretions,” the researchers wrote. “Viruses contaminating urine and feces can be aerosolized in building restrooms during toilet flushing. ... Because many viral infections may be asymptomatic, this is even more important in health care facilities where immunocompromised individuals are often present.”
The only way to reduce viral particles was to disinfect the toilet, toilet water, and nearby surfaces, the research team found. A separate study conducted by the same research team found that adding disinfectant to the bowl before flushing or using automatic disinfectant dispensers was equally effective in reducing contamination as a result of flushing.
“In healthcare settings, any potential means of pathogen transmission must be addressed to keep all of our patients—including the most vulnerable, such as immunocompromised individuals—as healthy as possible,” Charles P. Gerba, who has a doctorate in microbiology, is a professor of virology at the University of Arizona, and senior author of the study, said in a press release. “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.”
In the study conducted at the University of Arizona, scientists analyzed the spread of viral particles induced by flushing the toilet, both with toilet lids open and closed, to see if there was any difference in the outcome.
They seeded the toilets with varied amounts of a nonpathogenic virus, flushed the toilets, and then collected samples from the toilet bowl water and surfaces of the toilet, floor, and walls. They conducted this experiment in both household and public bathrooms.
In the household bathroom, there was no statistical difference in the amount of virus collected from the toilet surfaces or nearby floor between flushes with the lid closed or open. The only difference closing the toilet made was changing the direction of the aerosol plume, researchers noted. For example, when flushing with the lid closed, surfaces in front of and to the left of the toilet were more contaminated than surfaces on the right. The impact of closing lids on public restrooms wasn’t measured since they typically do not have lids.
The findings are important to keep in mind when one member of a household is sick, particularly when the infection is causing stomach issues, the study noted. Making sure regular disinfectant practices occur during a bout of illness can help prevent or reduce the spread of infection to other individuals in the household, especially if the home has only one bathroom.
Cleaning with a disinfectant is the most effective way to reduce viral contamination; disinfectants have a viral kill rate of 99.99 percent on the toilet and 97.64 percent on the toilet brush.
“This study helps establish a clearer understanding of how pathogens spread and the measures we can take to break those chains of transmission,” said Tania Bubb, who has a doctorate in nursing and is the 2024 Association for Professionals in Infection Control and Epidemiology (APIC) president, in the press release. “It also underscores the importance of regular disinfection of surfaces in healthcare settings for reducing the spread of viral infections.”
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