Should You Close the Toilet Lid After Using the Restroom? Study Reveals Complete Picture: 'Bacteria Spray Up to 163cm'

Should You Close the Toilet Lid After Using the Restroom? Study Reveals Complete Picture: 'Bacteria Spray Up to 163cm'

When you flush the toilet after using the restroom, do you have the habit of closing the lid? This seemingly minor action is actually a key step in preventing the spread of bathroom bacteria. Multiple authoritative international studies have confirmed that if the toilet lid is not closed during flushing, water droplets and aerosols carrying pathogens will spray into the air at high speed, reaching up to 163 centimeters above the ground—right within the breathing range of an average adult—and potentially contaminating toothbrushes, towels, and shower products stored in the bathroom.

According to a study published by the University of Colorado Boulder in the UK's prestigious journal Scientific Reports, the research team used high-frame-rate cameras and 'green laser light' to capture the trajectory of tiny water droplets during flushing.

The U.S. research team recorded the toilet flushing process using cameras. (Image: YouTube)

At the moment of flushing, water droplets and bacteria inside the toilet bowl are ejected outward at a speed of 2 meters per second. Within just 8 seconds, they can soar up to 1.5 meters (150 cm) high. While larger droplets settle within seconds, tiny 'aerosols' containing trace amounts of fecal matter, urine, or vomit residues can remain suspended in the air for over 20 seconds. If the user is infected with viruses such as COVID-19 or influenza, this increases the risk of subsequent inhalation or contact transmission.

A review by Flinders University in Australia, which compiled 22 related studies, also found that the high-speed water flow generated during flushing impacts the inner walls, releasing large amounts of airborne particles—reaching up to 163 cm in height. Lead researcher Lira Adiyani recommends making it a daily preventive habit to 'close the toilet lid before flushing,' which can significantly reduce exposure risk to pathogen-containing particles.

Stay Away from Bathroom Bacteria! Experts Share 3 Hygiene Protection Tips

In addition to developing the habit of closing the toilet lid before flushing, experts advise the public to follow these three bathroom hygiene measures:

- Always wash your hands thoroughly after pressing the flush button Whether at home or in public restrooms, after touching shared facilities or the flush button, be sure to wash your hands thoroughly with soap and dry them with clean paper towels or hand towels.

- Avoid leaving items exposed Toothbrushes, drinking cups, cosmetics, and shower products should be properly stored in cabinets with doors or covered with dust-proof lids to prevent contamination from airborne particles.

- Regularly disinfect the toilet and lid It is recommended to regularly wipe and clean with 75% alcohol, or use a solution of bleach diluted with water at a ratio of 1:1,000 to disinfect the toilet lid and seat. After letting it sit, rinse thoroughly with clean water.