< Hygiene

Can the SARS-CoV-2 coronavirus be caught by going to the bathroom?

Text updated on 2020-12-27


Yes, COVID-19 can transmitted in the bathroom by inhaling airborne viral particles and possibly by touching contaminated surfaces.

Bathrooms are narrow, unventilated rooms. At least one case of contamination in an aircraft lavatory has been reported: the contaminated person had removed his mask in the lavatory. So keep your mask on in the bathroom!

Viral particles are present in aerosols. These aerosols may have been exhaled by previous persons or produced when the toilet is flushed. Indeed, the stools of people infected with the coronavirus SARS-CoV-2 contain many viral particles. This appears to be related to the fact that the ACE2 receptor, to which the coronavirus attaches itself to enter cells, is present on the surface of the digestive tract. When the toilet is flushed, some water from the bowl is sprayed as droplets into the air (aerosolization). As a result, it is possible for the virus to be caught in the bathroom.

As a precaution: wash your hands thoroughly after using the toilet, regularly clean the seat with alcohol, use paper to touch the door handles, toilet seat cover, and toilet handles, and close the toilet bowl tight ly before flushing. Ventilate the bathroom with outdoor air as much as possible. Caregivers caring for young children and the elderly should also be especially careful when handling diapers.

Four studies have found contamination from toilet drains. In South Korea, Hong Kong, and Guangzhou, China, several people in apartments were contaminated by the drainage pipes that connected their bathroom to another apartment in the same building where their neighbours had COVID-19. Add water regularly to your drainage (U-shaped pipes) to keep them watertight.


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Sources

Very detailed study of the 310 passengers on a Milan-South Korea flight: medical check-up in the airport before departure, only the asymptomatic persons took the plane (11 symptomatic persons did not take the plane), masks mandatory for the whole duration of the flight except for the bathrooms, 14-day quarantine on arrival in Korea and medical follow-up during the 14 days, tests COVID-19. A 28-year-old was infected when she took off her mask to go to the bathroom on the flight from Milan to South Korea. This person had been quarantined for 3 weeks alone at her home in Italy before the flight and had not used public transport to get to the airport. She had the first symptoms 8 days after the flight. On the plane, she used the same bathroom as a pre-symptomatic person (tested positive 2 days after the flight). The 18 cabin crew and medical personnel were not contaminated. They all wore masks.

Bae, S. H., Shin, H., Koo, H. Y., Lee, S. W., Yang, J. M., & Yon, D. K. Asymptomatic Transmission of SARS-CoV-2 on Evacuation Flight. Emerging infectious diseases, 26(11).

Near a patient with COVID-19 in Singapore, who was coughing and had a mild form of the disease, the SARS-CoV-2 virus was found in large quantities on the toilet bowl.

Ong, S. W. X., Tan, Y. K., Chia, P. Y., Lee, T. H., Ng, O. T., Wong, M. S. Y., & Marimuthu, K. (2020). Air, surface environmental, and personal protective equipment contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient. Jama.

In the room of a person under quarantine in Qingdao, China, numerous samples were collected to detect the presence of the SARS-CoV-2 coronavirus. The largest amount of virus was detected on the toilet bowl.

Hu, X., Xing, Y., Ni, W., Zhang, F., Lu, S., Wang, Z., ... & Jiang, F. (2020). Environmental contamination by SARS-CoV-2 of an imported case during incubation period. Science of The Total Environment, 742, 140620.

SARS-CoV-2 coronavirus was isolated from the feces of 3 patients with COVID-19. Viral particles thus isolated from 2 of the 3 patients proved to be infectious when tested on cells in culture.

Fei X, Jing S, Yonghao X, Fang L, Xiaofang H, Heying L, et al. Infectious SARS-CoV-2 in Feces of Patient with Severe COVID-19. Emer. Disgusting. Dis. 2020; 26(8).

DNA from the virus (500-100,000 copies per mL) was found by RT-PCR in the feces of 9 out of 17 infected individuals tested, 0-13 days after the first symptoms. These amounts are less than those observed in respiratory specimens.

Pan, Y., Zhang, D., Yang, P., Poon, L., & Wang, Q. (2020). Viral load of SARS-CoV-2 in clinical samples. The Lancet Infectious Diseases, 20(4), 411-412.

Viral particles were found by RT-PCR in the feces of 8 individuals (including 6 children) among 27 infected people tested. Four weeks after the onset of infection, one adult and two children (2 and 3 years old) still had viral particles in their stool, but no longer had any in their nose and throat swabs.

Ma, X., Su, L., Zhang, Y., Zhang, X., Gai, Z., & Zhang, Z. (2020). Do children need a longer time to shed SARS-CoV-2 in stool than adults?. Journal of Microbiology, Immunology and Infection.

The virus is present in the feces of COVID-19 patients.

Wu, Y., Guo, C., Tang, L., Hong, Z., Zhou, J., Dong, X., ... & Kuang, L. (2020). Prolonged presence of SARS-CoV-2 viral RNA in faecal samples. The Lancet Gastroenterology & Hepatology, 5(5), 434-435.

A meta-analysis of 60 studies, representing a total of 4,243 COVID-19 patients, indicated that 17% of patients had gastrointestinal symptoms and 48% of patients had stool with viral particles during infection. Of these positive cases, 70% of stool samples, collected after observing no sign of the virus in respiratory specimens, still contained the virus.

Cheung, K. S., Hung, I. F., Chan, P. P., Lung, K. C., Tso, E., Liu, R., ... & Yip, C. C. (2020). Gastrointestinal Manifestations of SARS-CoV-2 Infection and Virus Load in Fecal Samples from the Hong Kong Cohort and Systematic Review and Meta-analysis. Gastroenterology.

During the SARS outbreak in 2003, 99 people living in the same building were infected from a single apartment where an infected person had diarrhea. A thorough study shows that flushing triggers resulted in aerosolization of viral particles that were present in the stool. These particles then spread into the bathroom, passed through an exhaust fan and then entered the apartments on the upper floors.

Yu, I. T., Li, Y., Wong, T. W., Tam, W., Chan, A. T., Lee, J. H., ... & Ho, T. (2004). Evidence of airborne transmission of the severe acute respiratory syndrome virus. New England Journal of Medicine, 350(17), 1731-1739.

Even after flushing the toilet several times, some of the viral particles are still present in the water in the toilet bowl. In addition, when you flush the toilet, many droplets containing bacteria and viral particles are formed and can end up more than one meter from the toilet bowl.

Gerba, C. P., Wallis, C., & Melnick, J. L. (1975). Microbiological hazards of household toilets: droplet production and the fate of residual organisms. Appl. approx. Microbiol, 30(2), 229-237.

Mathematical modeling that suggests the existence of an alternative route of transmission of the virus that does not involve direct person-to-person contamination.

Ng, T. W., Danchin, A., & Turinici, G. (2020). A new transmission route for the propagation of the SARS-CoV-2 coronavirus. DOI: 10.21203/rs.3.rs-17870/v1 Preprint

In April 2020 in Shanghai, some people testified that in quarantine, back from abroad, before leaving their hotel room, they were asked to decontaminate their bathrooms by adding chlorine tablets in the toilet bowl, waiting 1 hour, and then flushing (Xinyu Jia, personal communication).


Presence of SARS-CoV-2 in wastewater.

Medema, G., Heijnen, L., Elsinga, G., Italiaander, R., & Brouwer, A. (2020). Presence of SARS-Coronavirus-2 in sewage. medRxiv.

ACE2 protein is abundant in the lungs and small intestine.

Hamming, I., Timens, W., Bulthuis, M. L. C., Lely, A. T., Navis, G. J., & van Goor, H. (2004). Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis. The Journal of Pathology: A Journal of the Pathological Society of Great Britain and Ireland, 203(2), 631-637.

Indication that the SARS-CoV-2 virus induces lesions in the cells lining the small intestine and could thus lead to gastrointestinal symptoms.

Zhang H, Li HB, Lyu JR, Lei XM, Li W, Wu G, Lyu J, Dai ZM. (2020) Specific ACE2 Expression in Small Intestinal Enterocytes may Cause Gastrointestinal Symptoms and Injury after 2019-nCoV Infection . Int J Infect Dis. 2020 Apr 17. pii: S1201-9712(20)30238-1. doi: 10.1016/j.ijid.2020.04.027.

Two couples were infected because they lived in two apartments above an apartment where several people were infected with COVID-19. The three families did not know each other, and had not shared elevators during the contagion period. The investigation suggests that the contamination took place through flushing the toilets, which released aerosols that travelled through the drainage system and ended up in the bathrooms of the apartments. It is likely that the water from the U-shaped drainage traps under the bathtub had evaporated (as the bathtub is not used regularly) and therefore there was no longer a seal between the apartments. In addition, the two couples who were infected never opened their bathroom windows.

Kang, M., Wei, J., Yuan, J., Guo, J., Zhang, Y., Hang, J., ... & Peng, X. (2020). Probable evidence of fecal aerosol transmission of SARS-CoV-2 in a high-rise building. Annals of internal medicine.

At the Heng Tai house on the Fu Heng estate in Hong Kong, a 59-year-old man living in apartment 13 on the 34th floor was likely infected with two people with COVID-19 who live in apartment 13 on the 32nd floor.

Leung K., Leung C., Ho-him C. (2020) Coronavirus: at least 10 households evacuated from Hong Kong public housing block in Tai Po over multiple infections. South China Morning Post. Accessed on Dec 27 2020.

In the Luk Chuen building of Lek Yuen Estate in Hong Kong, 4 apartments in which 6 residents were infected - apartments # 710, 810, 1012 and 1112 on the 7th, 8th, 10th and 11th floors, respectively - were connected to the apartment of the index patient - apartment 812 on the 8th floor - by interconnected vertical drainage pipes.

Tsang D., Ho-him C. (2020) Coronavirus: Hongkonger living in public housing at centre of infection cluster confirmed as infected. South China Morning Post. 13 June 2020. Accessed on Dec 27 2020.

In a building in Seoul, people in 7 apartments were contaminated within a few days of each other. These people did not know each other and the 7 apartments shared bathroom drains.

Hwang, S. E., Chang, J. H., Bumjo, O., & Heo, J. (2020). Possible Aerosol Transmission of COVID-19 Associated with an Outbreak in an Apartment in Seoul, South Korea, 2020. International Journal of Infectious Diseases.

Further reading

How long is the coronavirus infectious?

What is the purpose of social distancing?

How do you wash your hands?

Is the SARS-CoV-2 coronavirus transmitted by aerosols?

What do the abbreviations COVID, SARS, CoV, RNA, etc. mean?

Why put on a mask?