Column

News

Drinking water very well protected against all viruses, including coronavirus

With the knowledge, experience and measurement methods that KWR has developed over the past decades within its Joint Research Programme with the water utilities, we are capable of quickly anticipating any potential threats. Over the last few weeks, microbiologist Gertjan Medema and his colleagues examined whether the drinking water in the Netherlands is well protected against the coronavirus. Conclusion: it is. A personal account.

When the first reports about the new coronavirus appeared in the media, I was immediately reminded of SARS. Naturally, since it’s the same kind of virus and it also originated in South-East China, where it was transmitted from animal to human. I thought back on Amoy Gardens, the high-rise complex in Hong Kong where SARS coronavirus (CoV) spread through the indoor sewer system and the ventilation system. An infected person visited his brother, used the toilet and introduced SARS CoV virus via his stools into the indoor sewer system. Sewer water droplets carrying SARS CoV then spread via the building’s ventilation system to other apartments, making 300 people sick.

At that time, the World Health Organization (WHO) asked me, together with other international experts, to assess the risk of the spread of SARS CoV through the sewer and/or water. The main route for the transmission of the virus was not water, but contact with infected people and surfaces. Nor is water a transmission route – or not an important one – for other coronaviruses. These viruses do not survive well in water, and they are easier to remove and inactivate than those viruses, such as the Noro- and the Adenovirus, whose waterborne transmission is frequently described. Nevertheless, the Amoy Gardens case did indicate that the water route was also a possibility for SARS CoV.

A new virus

When a new virus like this comes along, I want to know whether it can also be transmitted via water. Out of scientific curiosity, but primarily to be able to offer advice on the implications of the virus for the water sector. I have closely followed the coverage of the coronavirus for information about this. The news reports contained some indications: diarrhoea is one of the symptoms shown by a portion of the patients, and in Hong Kong, following the positive diagnosis of two patients from the same apartment complex, a study is being done to see whether the residents could become infected via the indoor sewer system.

Meanwhile, the new coronavirus continued its advance. The first European cases were reported, and ‘outbreaks’ of this new virus already extended further than those of SARS CoV in 2003. There was therefore a possibility that the virus would also come to the Netherlands. This presented a chance for us to study the ‘water route’ of the new coronavirus – which incidentally is so similar to SARS CoV that it is now called ‘SARS CoV2’.

Detection method

KWR has a great deal of experience with viruses in water, and the institute’s Microbiological Laboratory disposes of methods to concentrate, treat and detect viruses in water – we have done this for over 40 years, together with RIVM. Because the RNA code of the new coronavirus has been made widely available, we were able to rapidly get a detection method for the new coronavirus operational.

‘We would naturally like to repeat this research and extend it more widely, now that the coronavirus has been detected in the Netherlands.’ Prof.dr. Gertjan Medema

In the first week of February, contacts at the Dutch Water Authorities provided us with samples of wastewater from the regional water treatment plants of Amsterdam-West, Schiphol, Harnaschpolder, Amersfoort and Apeldoorn. We submitted them to our methods to determine whether they contained SARS CoV2 RNA sequences. The samples showed that the extraction had worked well. And no SARS CoV2 virus was detected in the analysed samples. Nor did we expect to detect any, since, up to that point in time, no cases had been reported in the Netherlands. But we had now set up an operational method, which would be prepared in the event that the coronavirus did reach the Netherlands. The method allows us to determine whether the virus also ends up and is detectable in wastewater, and whether wastewater screening provides a sensitive method to demonstrate the circulation of the virus among a human population. We have communicated the results to the regional water treatment plants concerned. We would naturally like to repeat this research and extend it more widely, now that the coronavirus has been detected in the Netherlands.

On 19 February (some researchers really move fast!) a paper was published in The Lancet on the faecal-oral transmission of SARS CoV2. STOWA has also already issued information about SARS CoV2 in wastewater. I have contacted microbiologists/virologists in China and Italy to see whether they would also want to research the transmission via sewage water. They are, after all, ahead of us when it comes to circulation in sewage water. We could collaborate to see whether we could collect more hard data about this new virus and the water route, so as to effectively underpin our recommendations to the (international) water sector and WHO.

Drinking water safe

The Dutch drinking water utilities and the branch association Vewin also want to know whether the coronavirus represents any risks to the safety of drinking water. Based on the knowledge that we’ve built up about viruses in drinking 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, which are also safeguarded by the Analysis of Microbial Safety of Drinking Water. Groundwater, in turn, is well protected in the subsurface against all microbial contaminants, including viruses. Moreover, the strict hygiene regulations covering the installation of pipes and work on the distribution networks, ensure that the drinking water sector is well protected against all microbial contaminants. We have let the drinking water utilities and Vewin know that drinking water is very well protected against all viruses, including coronavirus.