COVID-19 Germs May Go Airborne When Flushing Toilets with Lids Open

experts recommend closing toilet lids before flushing to avoid germ spread

By Jonny Lupsha, Wondrium Staff Writer

Plumes of COVID-19 germs may rise from flushed toilets whose lids are open, The Washington Post reported. Traces of the coronavirus have been detected in the fecal matter of treated patients, so experts recommend closing the lid before flushing. Plumbing fixtures are key in waste disposal.

Toilet with seat up
To keep germs from getting on surfaces and from lingering in the air in your bathroom, experts recommend that toilet lids should be closed before flushing. Photo by ShutterOK / Shutterestock

According to The Washington Post, researchers found some potentially unpleasant news regarding COVID-19 transmission. “Scientists who simulated toilet water and air flows say in a new research paper that aerosol droplets forced upward by a flush appear to spread wide enough and linger long enough to be inhaled,” the article said. “The novel coronavirus has been found in the feces of COVID-19 patients, but it remains unknown whether such clouds could contain enough virus to infect a person.

“The authors say the possibility of that mode of transmission calls for action in the midst of a pandemic—first and foremost, by closing the lid.”

The plumbing fixtures in your house play a major role in the disposal of waste and in keeping your house as clean as possible.

Plumbing Fixtures

The components that make up the disposal stream that leave your place of residence are far less disgusting than most people would imagine, and it all starts at a plumbing fixture.

“In general terms, a fixture is a device that draws clean water from the distribution system and discharges wastewater into the sewage system, without allowing any flow in the opposite direction,” said Dr. Stephen Ressler, Professor Emeritus from the United States Military Academy at West Point. “The most common residential plumbing fixtures—toilets, showers, bathtubs, sinks, and washing machines—all share this fundamental characteristic; a distinct break between clean water flowing in and dirty water flowing out, with no opportunity for the bad to contaminate the good.”

Dr. Ressler said that the real function of your household plumbing system is to capture all this wastewater and send it from your place of residence in a single stream.

Inside the Pipes

The waste stream that leaves your house is an unexpected mix of water and organic and inorganic items.

“The stream is composed of over 99.9% water, a number that seems quite surprising, until we recognize that the combined effluent from your sinks, showers, tubs, and washing machine far exceeds that of your toilets,” Dr. Ressler said.

“The remaining 0.1% is a complex and potentially unhealthy mixture that includes dissolved organic material, which originates from both human waste and food; suspended inorganic particles, or grit; rags, paper, plastic, and similar materials that somehow get flushed down toilets; and a high concentration of enteric microorganisms—bacteria that originate in our intestines and may include some pathogenic or disease-causing forms.”

According to Dr. Ressler, 75% of American residences send their wastewater through a sewer network to a centralized sewage treatment facility. The other 25%, which are mostly in rural areas, make use of on-site septic systems. However, almost every residence uses gravity-driven flow to rid itself of wastewater.

“Thus, with only a few exceptions, every conduit in the system—from that one-inch pipe that drains your bathroom sink to the four-foot-diameter sewer main carrying an entire city’s effluent to the treatment plant—must be placed at a carefully-controlled downhill slope, or gradient, to ensure the steady movement of the wastewater through the system,” Dr. Ressler said.

“Yes, as the old saying goes, this stuff really does flow downhill. And that’s why you’re quite likely to find your wastewater treatment plant at the lowest point in town.”

A lengthy process of filtration and treatment follows, but for most people, out of sight means out of mind—and it can start as soon as we close the toilet lid.

Dr. Ressler is Professor Emeritus from the United States Military Academy at West Point

Dr. Stephen Ressler is Professor Emeritus from the United States Military Academy at West Point and a Distinguished Member of the American Society of Civil Engineers (ASCE). A registered Professional Engineer in Virginia, he earned a BS from West Point and an MS and a PhD in Civil Engineering from Lehigh University, as well as a Master of Strategic Studies from the U.S. Army War College.