Can Viruses Survive in Water?

Can Viruses Survive in Water?

Scientists have confirmed that coronaviruses, like the CO19 virus, can remain infectious in sewage and drinking water for over the course of several days.

Two researchers, Haizhou Liu, an associate professor of chemical and environmental engineering at the University of California, Riverside, and Vincenzo Naddeo, director of the University of Salerno's Sanitary Environmental Engineering Division, have urged for additional testing to determine whether water treatment methods are effective at killing SARS-CoV-2 and coronaviruses in general.

The virus can be spread via microscopic water droplets or aerosols that enter the air via evaporation or spray, the researchers wrote in an editorial for Environmental Science: Water Research & Technology, the Royal Society of Chemistry's flagship environmental journal.

"The ongoing COVID-19 pandemic underscores the critical importance of conducting an in-depth examination of the path and control of this contagious virus in the environment," Liu said. "Environmental engineers such as ourselves are well-positioned to apply our expertise to these needs through international collaborations to safeguard public health."

During the 2003 SARS outbreak in Hong Kong, a sewage leak aerosolized a cluster of cases. Though there have been no confirmed cases of COVID-19 as a result of sewage leaks, the novel coronavirus is closely related to the one that causes SARS, and infection via this route is possible.

The novel coronavirus may also colonize biofilms that line drinking water systems, posing a risk of aerosolized transmission through showerheads. This mode of transmission is thought to be a significant source of exposure to bacteria such as those that cause Legionnaire's disease.

Fortunately, it is believed that the majority of water treatment processes effectively kill or remove coronaviruses in both drinking and wastewater. Coronaviruses are believed to be killed by oxidation with hypochlorous acid or peracetic acid, as well as by inactivation with ultraviolet irradiation and chlorine. The synergistic effects of beneficial microorganisms and the physical separation of suspended solids filter out viruses concentrated in sewage sludge in wastewater treatment plants that use membrane bioreactors.

However, Liu and Naddeo note that the majority of these methods have not been tested for efficacy against SARS-CoV-2 and other coronaviruses, and they have called for additional research.

Additionally, they recommend upgrading existing water and wastewater treatment infrastructure in outbreak hotspots that may have been exposed to coronavirus through hospitals, community clinics, and nursing homes. For instance, energy-efficient ultraviolet point-of-use systems based on light-emitting diodes could disinfect water before it enters the public treatment system.

Potable water reuse systems, which purify wastewater and reintroduce it as tap water, also require extensive investigation for coronavirus removal and, possibly, new disinfection regulatory standards, the researchers wrote.

Additionally, the extent to which viruses can colonize biofilms is unknown. Biofilms are slimy, thin bacterial growths that line the pipes of many aging water systems. Improved surveillance of coronaviruses in biofilms may be necessary to avoid outbreaks.

Increased use of bactericides, virucides, and disinfectants in the home will almost certainly result in an increase in antibiotic-resistant bacteria in the environment. Discharge of treated wastewater into natural waterways necessitates close monitoring throughout the water cycle. Liu and Naddeo invite chemists, environmental engineers, microbiologists, and public health professionals to collaborate on developing multidisciplinary and practical solutions for safe drinking water and healthy aquatic environments.

Finally, developing countries and some regions within developed countries, such as rural and impoverished communities, may be unable to eliminate SARS-CoV-2 due to a lack of basic infrastructure. These areas may be prone to frequent COVID-19 outbreaks, which are easily spread via globalized trade and travel. Liu and Naddeo argue that developed-country governments should fund and support water and sanitation systems wherever they are needed.

"Globalization, it is now widely recognized, also introduces new health risks. Where water and sanitation systems are insufficient, the likelihood of discovering novel viruses is extremely high "As Naddeo stated. "In a responsible and ideal world, developed country governments would support and finance water and sanitation systems in developing countries in order to protect their own citizens."

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