When Chinese and US research showed that the SARS Coronavirus 2 can also be present in faeces, and therefore also end up in sewage water, in February we immediately conducted an assessment of the knowledge concerning the possible waterborne transmission of the new coronavirus COVID-19. We compared this knowledge with the knowledge we have built up about viruses in water in the Netherlands over the last few years – for instance, within the Joint Research Programme with the water utilities – and with RIVM knowledge.
We concluded that drinking water in the Netherlands is very well protected against all viruses, including the new coronavirus. In the present report we reiterate why this is the case; we also give two examples of more in-depth research questions. After all, our purpose is not only to deduce, but also to acquire factual knowledge.
Protecting drinking water against viruses
Based on the knowledge that we have built up about viruses in water over the years in the Joint Research Programme, we know that the drinking water in the Netherlands is well protected against those viruses that are known to be transmitted via water, for example, the Adeno-, Noro- and Enterovirus. Drinking water utilities that produce their water from surface water sources have all set up multiple disinfection barriers for the purpose of removing bacteria, viruses and protozoa. This multiple disinfection is also safeguarded by the Analysis of Microbial Safety of Drinking Water (AMVD in its Dutch initials). Groundwater, in turn, is well protected in the subsurface against all microbial contaminants, including viruses.
Besides the AMVD, the drinking water sector applies strict hygiene measures – such as hygiene codes and other operational codes for drinking water – when installing pipes and carrying out work on the distribution networks, which prevent the contamination of the drinking water right up to the tap point. In 2018, RIVM and KWR jointly supported the Dutch drinking water sector to ensure that it amply satisfied the WHO guidelines of the Water Safety Plan (Van den Berg et al. 2018).
SARS Coronavirus 2 in water
Coronaviruses are less robust in the sewage and aquatic environment than are those viruses upon which the viral safety of our drinking water is based. Coronaviruses become inactive more quickly and are easier to remove and inactivate in water treatment processes. The existing measures that ensure the drinking water safety against the known viruses therefore also do the same against this new, weaker virus.
We have detected RNA viral fragments in sewage water in our corona virus sewage water research. We are also keeping track of the results of the rapidly accelerating scientific work on the new virus for indications of its possible transmission via water. None have appeared. In no country have there been any signs that people have become infected with SARS-CoV-2 through contact with water, wastewater or even the faeces of people with COVID-19. The faeces show the presence of lots of viral RNA, but no, or barely any, contagious viruses. It appears that the virus does actually infect intestinal cells, but that it does not survive well in faeces. Italian researchers have analysed the sewage water of Milan, and did indeed find the RNA of SARS-CoV-2, but they could not find any contagious viruses through cell cultivation methods.
In the current situation, no further research is needed to demonstrate that drinking water is safe. If significant amounts of SARS-CoV-2 RNA from sewage water were to end up in surface water, we could apply the monitoring method to the surface water used as a source in drinking water production (Maas, Haringvliet, Lek, IJssel, Drentse Aa, Ijsselmeer and others). We would then compare the concentrations of SARS-CoV-2 with concentrations of Entero- and Adeno-viruses, upon which the drinking water safety is based, in line with the AMVD.
We could also conduct experimental laboratory research to strengthen the knowledge about the survival of coronaviruses in water and about disinfection through treatment processes (UV and chlorine). This would corroborate that this virus is indeed less persistent and easier to inactivate than the viruses that our drinking water protection is built for.
If you have questions about the coronavirus and (sewage) water, please visit our Q&A page. If you still have a question that you don’t see answered on the page, you can send it to us by using the special form available.