Water quality researchers with the Southern Nevada Water Authority (SNWA) are pursuing a novel method to detect and monitor for the presence of the novel coronavirus in sewage wastewater. The high-tech detective work uses the emerging science of wastewater epidemiology to find and measure the genetic markers of the coronavirus in untreated sewage and better understand the prevalence of the virus within the local community.
“Our water quality testing confirms the COVID-19 virus is not in our drinking water, nor is it found in our community’s treated wastewater,” said SNWA Water Quality Research and Development Manager Dave Rexing. He added that the virus also has not been found in the Las Vegas Wash, which channels more than 180 million gallons of highly treated wastewater effluent to Lake Mead each day, extending Southern Nevada’s water supplies in a safe and sustainable manner.
“We can detect the genetic signature of the coronavirus in raw sewage before it’s treated. While the virus is likely not active or even structurally intact at this stage, we can still detect its presence—similar to detecting its fingerprint,” said Principal Research Laboratory Scientist Dan Gerrity. The COVID-19 virus is primarily respiratory in nature, though studies have confirmed the presence of its genetic material in the feces of infected individuals.
While the coronavirus is not present in Southern Nevada’s drinking water, SNWA researchers are measuring the presence of the virus in untreated sewage wastewater and collecting data along with other researchers across the country. The scientists are collaborating and sharing data to better understand how the coronavirus may influence water and wastewater industries.
Initial research shows that the COVID-19 signal disappears early during wastewater treatment and that water treatment processes should be effective in destroying the virus, but scientists want to determine whether or not there are risks from the untreated wastewater supply – particularly from aerosolization in sewers and during the primary or secondary wastewater treatment processes.
“We also believe the information we’re collecting about the virus will be a critical piece of the puzzle in determining its overall prevalence within a community, particularly as clinical testing remains limited,” Gerrity said.
Due to the lack of wide-scale testing throughout communities, determining the prevalence of the novel coronavirus among the population is difficult. By combining the data SNWA is collecting with the coronavirus clinical data, the community may have a better understanding of the presence of the virus in Southern Nevada.
Gerrity and Rexing note that as the virus dissipates in the community, the markers for it will disappear from the weekly samples of untreated wastewater. With SNWA’s robust water quality monitoring and testing activities, the agency will be able to quickly detect the presence of the virus if it spikes or returns.
“This research may be able to serve as an early warning system,” Gerrity said. “Should the virus spike or return, we will be able to detect the virus in its early stages. This could give officials advanced notice—perhaps before confirmation of new clinical cases.”
SNWA researchers are working with the Water Research Foundation and other scientists from across the United States to determine the level of disease in multiple communities through the study of wastewater – known as “environmental surveillance” or “wastewater epidemiology.”
Scientists in the Netherlands pioneered much of the initial wastewater epidemiology research. They were able to detect the coronavirus in sewage samples in some areas of the country even before anyone was officially diagnosed in that community.
“This is emerging research, but it demonstrates the commitment wastewater and water agencies have to applying science to help protect public health,” Gerrity said.
“With our advanced water quality research and development laboratories and our expert staff, we are in a unique position to help water, wastewater and scientific communities better understand the implications of this virus on water supplies,” Rexing said, again emphasizing that Southern Nevada’s drinking water continues to meet and surpass state and federal drinking water standards. “Our water treatment processes are effective at removing contaminants and microorganisms such as viruses.”