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Covid-19 could infect the water supply, say researchers

Scientists are calling for more research into whether current water treatment methods are enough to kill Covid-19 to ensure it is not being spread through water infrastructure.

It is already known that coronaviruses, including Covid-19, can remain infectious for days or even longer in sewage and drinking water.

The virus is also commonly transported in microscopic water droplets, or aerosols, which enter the air through evaporation or spray.

“The ongoing Covid-19 pandemic highlights the urgent need for a careful evaluation of the fate and control of this contagious virus in the environment,” said University of California researcher Haizhou Liu. “Environmental engineers like us are well positioned to apply our expertise to address these needs with international collaborations to protect public health.”

During a 2003 Sars outbreak in Hong Kong, a sewage leak caused a cluster of cases through aerosolisation. Although this has not occurred during the current pandemic so far, its similarities to Sars mean this infection route could be possible.

It is also thought Covid-19 could colonise biofilms that line drinking water systems, making showerheads a possible source of aerosolised transmission. This transmission pathway is already thought to be a major source of exposure to the bacteria that causes Legionnaire’s disease.

Most water treatment routines are thought to kill or remove coronaviruses effectively in both drinking and wastewater. Oxidation with hypochlorous acid or peracetic acid, and inactivation by ultraviolet irradiation, as well as chlorine, are thought to be enough to eradicate the virus.

However, the researchers have cautioned that most of these methods have not been studied for effectiveness specifically on Covid-19 and other coronaviruses and are calling for additional research.

They also suggest upgrading existing water and wastewater treatment infrastructure in outbreak hot spots, which possibly receive coronavirus from places such as hospitals, community clinics and nursing homes.

Energy-efficient, light-emitting, diode-based, ultraviolet point-of-use systems could disinfect water before it enters the public treatment system. Potable water-reuse systems, which purify wastewater back into tap water, also need thorough investigation for coronavirus removal, and possibly new regulatory standards for disinfection, the researchers said.

“It is now clear to all that globalisation also introduces new health risks. Where water and sanitation systems are not adequate, the risk of finding novel viruses is very high,” said researcher Vincenzo Naddeo.

“In a responsible and ideal scenario, the governments of developed countries must support and finance water and sanitation systems in developing countries, in order to also protect the citizens of their own countries.”

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