A new study published in the Physics of Fluids journal warns that it’s possible to contract COVID-19 when flushing a toilet previously used by an infected individual.
Although coughing and a fever remain some of the most common symptoms of COVID-19, some infected people experience diarrhea and vomiting. Additionally, researchers have found large amounts of the virus in fecal matter of COVID-19 patients, and it remained in stool samples even after the virus was cleared from the patients’ lungs, according to the Washington Post.
Researchers believe COVID-19 can spread via toilet use when an infected patient flushes without closing the toilet lid. The study in the Physics of Fluids journal found that when people flush, “an upward velocity of as much as 5 m/s (meters per second) is produced, which is certainly capable of expelling aerosol particles out of the toilet bowl.”
The study also found that 40%–60% of the total number of particles can potentially extend above the toilet seat and cause large-area spread—and this spreading can continue up to 70 seconds after flushing occurs.
“As can be seen from our daily experience, flushing a toilet can cause violent turbulence, which will aid large-scale spread of viruses present in the toilet bowl,” the study said. “It has also been shown that flushing the toilet without putting the lid down is a bad habit.”
The World Health Organization and the Centers for Disease Control and Prevention don’t think this revelation is anything to be concerned about, however. The CDC said it believes it’s unlikely that the spread that occurs in bathrooms is “capable of causing COVID-19.”
“There has not been any confirmed report of the virus spreading from feces to a person. Scientists also do not know how much risk there is that the virus could be spread from the feces of an infected person to another person,” the CDC wrote. “However, they think this risk is low based on data from previous outbreaks of diseases caused by related coronaviruses, such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).”
Either way, most will agree that it’s better to be safe than sorry—especially since the study backed up that all kinds of noroviruses can spread in bathrooms. Luckily, it’s relatively easy to stop the spread of transmission from flushing a toilet. The study recommends that people close the toilet before flushing when possible, clean the seat before using it, and wash hands thoroughly after use.
Joe Allen, the director of Harvard’s Healthy Buildings Program, told National Geographic that businesses could help stop transmission by installing lids onto toilets, improving ventilation in restrooms, and investing in hands-free technology for water faucets and soap dispensers.