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What's the future of wastewater testing for COVID-19?


In the wake of the Walkerton tragedy in 2000 when seven people died and 2,300 were sickened by an E. coli breakout in the Ontario town's drinking water, Justice Dennis O'Connor, who led an inquiry into the tragedy and brought changes to strengthen drinking water protections in Canada, warned that the "keynote in the future should be vigilance."

"We should never be complacent," O'Connor said.

And nearly three-and-a-half years since the start of the COVID-19 pandemic, O'Connor's call for vigilance in the service of public health needs to be remembered and applied to COVID-19, said Prof. Mark Servos.

He's the Canada Research Chair in Water Quality Protection at the University of Waterloo’s biology department, and he played an instrumental role in the effort to get wastewater testing off the ground, in Ontario and across the country.

Wastewater surveillance became an important tool for detecting COVID-19 outbreaks in communities throughout the pandemic, and it continues to be used in search for coronavirus SARS-CoV-2 as well as other pathogens.

But it's unclear whether current levels of government funding to monitor wastewater for SARS-CoV-2 will continue beyond next year. Experts are calling on the federal government to create a standardized system for wastewater surveillance to bolster and replace the patchwork being used today.

People who are infected shed the SARS-CoV-2 virus before symptoms set in and while they're sick, not only from nose and mouth exhalations, but also in their feces.

A sample of wastewater monitoring data for the presence of SARS-CoV-2 across cities, as provided by the Public Health Agency of Canada (CTV News)

As of the latest update by the Public Health Agency of Canada (PHAC) on July 28, 41 per cent of wastewater monitoring sites across the country showed decreasing levels of COVID-19 in wastewater, while 28 per cent showed an increase.

Meanwhile, COVID-19-related hospitalizations in Canada continue to decline along with the number of patients in intensive care units. Infectious disease specialist Dr. Isaac Bogoch warns, however, that this is "about as good as it's going to get for a while," as we can expect most "parameters will likely rise sometime in the fall."

Professor Mark Servos, Canada Research Chair in Water Quality Protection in the University of Waterloo’s Department of Biology, removes a manhole cover. Before the pandemic, his research focused on the impact of trace contaminants on fish and other aquatic life. (Source: University of Waterloo)

The detection tool positioned to catch such a rise early is wastewater surveillance, which doesn't rely on people getting tested or testing themselves and reporting the result.

But experts like Servos point out that as the severity of COVID-19 cases wanes, so have the number of tests being conducted, because various jurisdictions across Canada have either ended or have scaled down pilot projects keeping track of the concentration of the virus in various cities and communities.

"Wastewater testing continues across Canada but at a reduced intensity," Servos told "Ontario used to have 170 testing sites, it’s now down to 70. Quebec has only four sites now."

PHAC continues to test, but its data covers just 39 testing sites for all of Canada.

Researchers say the reduction in testing is a trend that shows complacency may be creeping in after three years of effective vigilance that wastewater surveillance has provided, in not just detecting the virus in communities but identifying trends and giving a crucial head start to institutions that have been making public health decisions.


A recurring refrain by experts who spoke with has been the need for a federal strategy to create a system of wastewater monitoring for COVID-19.

"As it exists now, we're kind of siloed," said Robert Delatolla, director of the wastewater group of CoVaRR-Net research network and a civil engineering professor at the University of Ottawa.

Delatolla pointed to the different programs being run in each province from B.C. to Quebec.

"Then there's initiatives of people doing it in the eastern portions of the country. And then you have PHAC, which runs a program where they do certain sites across the country," Delatolla told

Professor Robert Delatolla poses in front of a pumping station used to collect wastewater samples that are screened for COVID Thursday April 8, 2021 in Ottawa. THE CANADIAN PRESS/Adrian Wyld

"So we have a number of programs but they're all independent; and the datasets from each of those programs are not related, nor do they link up with each other."

Scientist Mike McKay, who worked closely with Delatolla and Servos to get wastewater testing off the ground and running in Ontario, agreed.

"Unfortunately, it's been sort of piecemeal," he told "And I understand why, because they have to wait for the provincial budget to come down and funds released for these activities."

Typically, the Government of Ontario releases its annual budget each spring. Right now, provincial funding for wastewater testing across the province is set to end at the end of March 2024.

"After that, who knows?" said McKay. "I think there's consensus that this is too valuable a tool to drop. But the problem, you know, it's considered monitoring -- and as I know well from my work in the Great Lakes, monitoring is often the first thing to be cut from budgets when there's not a problem."


McKay is executive director and a professor at the University of Windsor's Great Lakes Institute for Environmental Research. His research focuses on large lakes, where he studies harmful cyanobacterial blooms -- or "the green-coloured scum on the lakes," as he described them -- among other microbiological organisms. But unlike Delatolla, he had never worked with wastewater before the pandemic.

"You know, there were a lot of us who made pivots during the pandemic to join the ranks of those who were trying to combat COVID-19. And I'm one," he told His lab group transitioned to wastewater surveillance in support of public health, soon after hearing about a team in the Netherlands that successfully detected SARS-CoV-2 in wastewater at Amsterdam Schiphol airport in March 2020.

Executive director of the Great Lakes Institute for Environmental Research Mike McKay (left) and environment professor Ken Drouillard (right) in Mitchell's Bay, Ont. on Tuesday, Feb. 15, 2022. (Chris Campbell/CTV Windsor)

Even Delatolla, whose job focuses on biological wastewater treatment and surveillance of disease, had to do a mental pivot when it came to the concept of monitoring wastewater for the presence of the virus.

In fact, it was in mid-March of 2020 when his wife suggested he start looking for SARS-CoV-2 in wastewater.

"And I told her, absolutely no, it makes no sense. It's a respiratory disease," he told "And then, of course, a few days later, the Netherlands found it in wastewater. So we said, OK, we'll do it. And we started to look and we were very fortunate to be the first group in Canada to detect it."

Hadi Dhiyebi, an environmental biologist at the University of Waterloo and part of Mark Servos' group, said he remembered Servos discussing the Netherlands findings with Bernadette Conant, who was at the time CEO of the Canadian Water Network (CWN).

"Back when the lockdown occurred in March of 2020, no one approached us. But (Conant) was in conversation with Mark and highlighted that group in the Netherlands doing wastewater surveillance which coincided with clinical cases, and could be useful," said Dhiyebi. "So Mark rang me up and asked if we’d be able to replicate that with our samples. Before anyone really approached us, Mark took it upon himself to see if we can develop this technique."

Hadi Dhiyebi is the Water Quality and Ecotoxicology Technician at the University of Waterloo's Global Water Futures Program and part of the Servos Group (Source: University of Waterloo)

He recalled at the time there being "a lot of open collaboration around the world" to share knowledge, and with wastewater being so different everywhere, they "had to validate the methods for our solutions."

Delatolla said this open sharing of knowledge allowed things to move quickly, and the virus that causes COVID-19 was detected in local wastewater a few weeks later in April.

He approached Servos and McKay to share his process, before eventually going to the Ontario COVID-19 Science Advisory Table – a group of independent scientists that gave advice to the Ontario government about COVID-19.

After meeting with the advisory table a number of times, Peter Juni, who was the scientific director at the time, approached Delatolla's group about building a program.

"And we worked together and we developed what is the Wastewater Surveillance Initiative," said Delatolla, the program in Ontario now being funded until March 2024.

This initiative ballooned into a collaboration involving 13 universities, 22 public institutions, 22 professors and 175 locations across Ontario.

"Really the dominant kind of surveillance program in the country," said Delatolla. At its height there were 260 wastewater locations in the country being analyzed and Ontario had 175 of them. "So they really did create a very high-level program."

By the time September 2020 came around, they were testing wastewater every day and sharing the data with public health departments.

"And we had our data, live, for the public to see in Ottawa. So I think we had the longest dataset, the longest daily dataset in North America, maybe in the world," said Delatolla.


Chand Mangat, a researcher at the National Microbiology Lab in Winnipeg, was used to working with wastewater. In 2019, for example, he was researching wastewater surveillance technology to monitor anti-microbial resistance, "and I was just getting started to reckon with what this technology was and how it might help in the control the rise of anti-microbial resistance."

Through that project, his group partnered with Environment Canada as well as Statistics Canada, which had a network of wastewater monitoring sites and professionals who had been testing wastewater for the presence of illicit drugs.

"So early on in the pandemic, just talking with the StatCan folks and looking at the data that was coming out internationally, a decision was made to put our full effort into it," he told "We saw what was going on around at the agency. So many groups were getting pulled into the pandemic response. And it was just right in a situation like that where it's all hands on deck to direct your efforts to the same problem.

Mangat is also head of PHAC's Wastewater Surveillance Unit in the One Health Division, as well as a member of CoVaRR-Net. "We didn't know how we would fit in, but we knew that we were available to others," said Mangat. But the biggest obstacle was that there wasn't a prior program in this specific area in place. 

"There wasn't a wastewater surveillance activity on the organizational chart, know what I mean? So we had to do things like build a lab, hire staff, get equipment in. And all of that happened at a tremendous pace," he said. 

Other experts who spoke with say all this could not have happened had so many in the field – directly and tangentially -- not jumped aboard the effort.

Wastewater surveillance isn't a new science. The practice of monitoring wastewater for pathogens has been used for decades and the virus that causes polio was isolated from wastewater back in 1932 in Philadelphia.

But using it to reliably track COVID-19 infections required "innovation, complex science and collaborative partnerships," said Bahar Aminvaziri, director of the Wastewater Surveillance Initiative at Ontario's Ministry of Environment, Conservation and Parks.

She outlined to that it took an "unprecedented" level of cooperation from a multi-disciplinary team of scientists, engineers and technical specialists to support academic and research labs.

"Researchers such as Dr. Servos who had already developed laboratory protocols for this kind of testing, sprang into action, demonstrated extraordinary leadership and shared their knowledge with other research teams in Ontario to create a competent network of 13 research laboratories with a large service capacity," Aminvaziri told

She added that the province's municipalities and operators of wastewater treatment plants also came forward "with remarkable enthusiasm and drive to do their part and make sure samples were provided regularly."

Delatolla said the pandemic showed just how quickly organizations could band together to collectively help deal with a public health crisis.

"From a personal perspective, I think it was the most impactful part of my career. I was amazed by how collaborative everybody was and in the scientific community, that was clearly impactful," he said.

"I think there's a lot of lessons learned here. There was funding applied that was applied quickly. People were motivated. There (were) a lot of barriers removed, that sort of slows down our progress."

McKay added he was amazed by the cooperation by all the different groups throughout the pandemic.

"I look back and it's been a weird but sort of wonderful past few years. The collegiality of that wastewater consortium has been amazing," he said. "I'm sure partly it was because of the pandemic, but oftentimes when we think of academia, you've got groups competing and people are secretive and not sharing. And this has been one of hope and sharing, working with each other to develop techniques for common good."


Delatolla said wastewater testing has put a spotlight on another important issue when it comes to monitoring the health of different communities, and that issue is health equity.

"We've seen during COVID that the disproportionality of deaths between vulnerable populations, underserved populations, versus the mean across the country has been shocking to those of us who don't see that data every day," he said. "And I think this wastewater work has also been shown to be able to go to communities, shelters, long-term care facilities, remote communities, Indigenous communities, First Nations communities. We've seen that doesn't get published as much. It doesn't make it to the media as much, but that work is definitely happening."

But he said the impact of the work is there, is being felt, and will continue to make a difference.

"So I think there's two parts of this. Let's be prepared for future pandemics, but also in the meantime and going forward, continue to serve and promote health equity across this country. Because it's a really cheap way to get a lens onto the health of a community."

A wastewater sample is taken in the Northwest Territories. (Credit: Justin Hazenberg)


Similarly, Mangat spoke of the power and scope of wastewater testing when it comes to measuring the disease burden in communities.

"The pandemic was a pretty dynamic situation with respect to who we were testing, when we were doing that testing, and how available it was," he told, "and probably a pretty central feature of wastewater surveillance is that none of that matters, right? Because so long as people are using the bathroom, they're counted."

"And that's, I think, important to us from an equity standpoint, because it doesn't matter if you're able to interact with the health care network or testing infrastructure. If you're using the facilities you're contributing to the surveillance system." Top Stories

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