How can COVID-19 be transmitted through sewage, wastewater and other similar environments?

There is no evidence that water is a transmission route for the SARS-CoV-2 virus, which causes COVID-19. RNA fragments of the virus have been detected in sewage water, but they have a low probability of being infectious particles. Therefore presence of the SARS-CoV-2 virus probably poses small risks of acquiring COVID-19. Nevertheless, exposure to sewage wastewater has a (proven) risk of becoming infected by other pathogens, for which professionals working with sewage wastewater already have their (normal) personal protective equipment. Therefore RIVM and WHO (and other health services, such as US CDC) indicate that normal protection and hygiene measures are adequate. The same conclusion holds for the SARS virus (SARS-CoV) which is another coronavirus closely related to the COVID-19 virus (which is therefore called SARS-CoV-2). Inactivation experiments with SARS virus (Duan et al. 2003) revealed that the virus remains infectious in stool at 20 ºC for 4-5 days. Higher temperatures accelerate the inactivation of similar viruses (Kampf et al., 2020). Another study examined inactivation of other coronaviruses in sludge at 25 ºC and found 99.999-99.9999% (log removal rate (e.g. 99% = 2 log, 99.999% = 5 log)) inactivation in 3 weeks (Casanova et al. 2009). These authors had pre-pasteurized the sludge, which stopped the biological activity of the fermentation. Inactivation in unpasteurized sludge at 30-38 ºC is expected to occur faster. On the basis of the available knowledge it can be stated that, if infectious SARS-CoV-2 virus is present in sewage (which is already unlikely), the sludge fermentation (part of many sewage treatment processes) can completely inactivate the virus.