Leaving a toilet lid open during a flush creates an invisible cloud of aerosolized microbes that spreads throughout the bathroom and settles on nearby hygiene items, according to infectious disease specialist Bruce Hirsch.
Speaking in an article for Martha Stewart's lifestyle publication, Hirsch warned that the sudden force of a flushing toilet operates like a powerful hydraulic cannon.
A typical flush forces between 1.28 and 1.6 gallons of water out in seconds, reaching speeds of up to 48 gallons per minute. This sudden pressure launches microscopic water droplets and waste residue into the air, reaching heights of up to 1.5 meters.
The resulting microscopic aerosol contains intestinal pathogens including Salmonella, E. coli and Shigella, which then coat surrounding bathroom surfaces such as walls, sinks, towels and toothbrushes. These bacteria are common causes of gastrointestinal illness.
Threat of C. diff infection
Hirsch highlighted the specific danger posed by Clostridioides difficile, a resilient bacterium that causes severe intestinal damage. The pathogen is responsible for half a million infections in the United States every year, often affecting people whose healthy gut flora has been disrupted.
Hirsch said the microbe causes unbearable, sometimes explosive and foul-smelling diarrhea, alongside toxic colitis that affects the entire body. The only simple solution, he added, is to always close the lid before pressing the flush to ensure the intestinal bacteria are sent to a wastewater treatment plant.
Routine bathroom cleaning
Despite the risk of aerosolized bacteria, Hai Hoang, founder of the cleaning company Simply Maid, said people do not need to use harsh chemicals after every use of the toilet. Regular cleaning is entirely sufficient for a healthy household, with enhanced disinfection only necessary when a family member is ill.
Hoang advised households to dedicate a specific cleaning cloth solely for the toilet. He recommended regularly wiping down the exterior surfaces, including the flush button, the hinges, both sides of the seat, and the surrounding floor.
When cleaning, Hoang said to leave household chemicals on the surfaces for the exact time specified in their instructions, and reminded people to wash their hands with soap for a minimum of 20 seconds.
