Flushing Toilets Can Launch Coronavirus Droplets. Here’s the Easy Fix
Wed, April 21, 2021

Flushing Toilets Can Launch Coronavirus Droplets. Here’s the Easy Fix



The World Health Organization has shared how the Covid-19 virus spreads primarily through droplets of saliva or discharge from the nose when an infected person sneezes or coughs. This is why calls for isolation and social distancing have become the pandemic battle-cry in different parts of the world. It has also been recently found that flushing toilets promote coronavirus transmission as it can launch aerosol droplets nearly three feet into the air. This is according to a study that appeared in the journal Physics of Fluids.


Toilet usage and virus transmission

Yun-yun Li from Southeast University’s School of Energy and Environment and colleagues wrote in the abstract of their study that fecal-oral transmission is a common route for many viruses, including the novel coronavirus. Since fecal-oral virus transmission usually happens in toilet usage, blocking the path of such transmission is of fundamental importance in suppressing the spread of Covid-19 that is causing public health crisis, panic, and economic losses in many countries.


Flushing-induced turbulent flow

However, the efforts to improve the sanitary safety of public toilets remain insufficient up to date. The authors added that flushing a toilet generates turbulence within the bowl and such flow expels aerosol particles that contain viruses. Droplets can even travel up to 3ft or 91cm from the ground level or above the bowl based on the computational fluid dynamics used by the Chinese scientists in the study.



Putting the toilet seat down

So, what’s the solution? Put the toilet seat down before flushing to avoid spreading the coronavirus. Study co-author Ji-Xiang Wang from Yangzhou Univesity’s College of Electrical, Energy, and Power Engineering said via BBC that as water pours during a flush, it creates turbulence and droplets. These small droplets typically float in the air for more than a minute, the reason why precautions should be observed when using the toilet. Wang added that the velocity (direction and rate of motion) is even higher if the toilet is used frequently, such as a public toilet in a densely populated area or a family toilet during a busy time.

The researchers investigated two types of toilets: one that creates the rotating flow of water and the second with a single fill-valve. They then applied the discrete phase model (DPM), which has been successfully applied in the droplet movement in spray cooling and dust particle diffusion movement as part of pollution control.  The purpose of the group for applying DPM is to simulate the movement of small droplets that are likely to be launched from the toilet bowl into the air. The result shows that water pouring into the toilets formed vortices (whirlwind) that carry virus-infected particles.

Since the virus can stay in the air for a minute, it can settle on other surfaces or be inhaled by the next person to use the toilet. It was also found that double fill-valves toilet, sometimes referred to as inlets, can produce a greater whirlwind of virus-infected droplets.



Fecal–oral transmission of Covid-19

Detection of Covid-19 in sewage and stool has been reported before Li and the team’s study, raising the hypothesis of fecal-oral transmission that could have far-reaching consequences for pandemic control and public health strategies.

As of June 17, global coronavirus cases reached 8,274,587, including the 4,333,411 patients who recovered. While there is currently no vaccine to prevent coronavirus diseases, the public is advised to avoid being exposed to the virus. Recent studies also suggest the use of hand sanitizer that contains at least 60% alcohol if soap and water are not readily available. Cleaning and disinfecting surfaces are also advised.  This includes doorknobs, phones, keyboards, sinks, faucets, toilets, countertops, light switches, and tables.




Toilet model structures

Aside from suggestions concerning safer toilet use, the researchers also hope that their findings will prompt a better toilet design. For instance, it could have a lid that automatically closes before flushing. They also mentioned a new design of waterless toilets that could prevent the transmission of pathogens. Yet, because of the widespread use and popularity of normal water-based toilets, it may take some time to introduce such a waterless toilet. Therefore, at present, the team wants to raise public awareness of bad habits when using a toilet that increases the risk of virus transmission.

University of Nebraska Medical Center professor of pathology and microbiology Joshua L. Santarpia, who was not involved in the study, told the New York Times that Li and the team’s study adds to the evidence that everyone should take better action. It has been known for a while that flush toilets produce substantial quantities of aerosol but the public has taken it for granted.

An average person is said to flush the toilet six or eight times daily or 2,500 times a year, says the World Toilet Organization. However, not all toilets flush. Toilets and adequate sanitation are necessities that ensure the well-being, dignity, and health of all but 40% of the world’s population still do not have access to toilets. Because of the sanitation crisis, 1,000 children died per day in 2013 from diarrhea diseases but these deaths are preventable. Furthermore, for every $1 spent on sanitation and water, it generates $4.3 return in the form of reduced costs for health care.




People practicing open defecation

The World Toilet Organization, which is a nonprofit organization committed to improving toilet and sanitation conditions worldwide, also stated that safe and clean toilets increase the attendance rates of girls in school. Far too many girls miss out on an education because of a lack of safe and clean toilet and this gets even worse during their periods.

Meanwhile, the World Bank states that 22.059% of people in the world practice open defecation but this declined to 9.054% in 2017. Countries with a high number of people practicing open defecation by % of population include Namibia (48.713%), Sudan (24.313%), Chad (66.989%), Niger (67.849), Benin (53.832%), Burkina Faso (46.665%), Liberia (39.612%), Madagascar (44.576%), and Mauritania (31.932%).

The study thus emphasized the importance of putting the toilet seat down before flushing, cleaning the toilet seat and other contact areas frequently, and washing our hands after using the toilet to reduce coronavirus transmission.