Faulty plumbing and a poorly designed air ventilation system were believed to be factors in a 2003 Severe Acute Respiratory Syndrome (SARS) outbreak. The system allowed the virus, SARS-CoV-1, to be aerosolized in faecal matter and enter multiple apartments through improperly functioning bathroom drains (WHO report). Given that SARS-COV-2 is very closely related to SARS-CoV-1, there are concerns that COVID-19 might be transmitted in the same way. Faeces could also potentially become aerosolized or released into the air in droplets as a result of mechanized emptying of on-site sanitation systems or toilet flushing. Transmission via aerosolized faeces is possible but unlikely based on current occurrence and survival data of SARS-CoV-2 in faeces.
WHO recommends flushing toilets with the lid down, especially in health facilities treating patients and the use of standard, well-maintained plumbing and wastewater treatment systems. Plumbing systems should include sealed bathroom drains and backflow valves on sprayers and faucets to prevent aerosolized faecal matter from entering the plumbing or ventilation system.