It was years before the COVID-19 pandemic struck that the city of Tempe and Arizona State University embarked on an effort to curb a public health crisis by monitoring wastewater. The city was among the first in the nation to monitor wastewater and communicate results with the public on an online dashboard.

In 2018, Tempe began monitoring the area’s wastewater for opioids as the number of opioid-related overdoses remained high and concerns swelled around kids in middle and high school becoming addicted. The wastewater-monitoring system allowed for the city to put extra resources in the zones of the city that were seeing a higher amount of opioids in the wastewater, such as more education for the students in that zone and naloxone for first responders to reverse an active overdose.

“We were trying to fight an epidemic,” Tempe Deputy City Manager ​​Rosa Inchausti said. “We were using this data-driven approach and bringing science right into the living room of our residents. We didn’t want to start this and not communicate with residents. We always wanted to do something with the information we gathered and communicate outcomes.”

In 2020, after the COVID-19 pandemic gripped the world, Tempe and ASU began testing the city’s wastewater for COVID-19—to better identify hot spots in the city and allocate more resources and information in those areas. It allowed for even more localized data to drive the decisions of City Council, Inchausti said.

Now, two years later, Tempe is one of dozens of wastewater-testing sites across the country and is looking to the future of biointelligence. Public health officials; Inchausti; and Rolf Halden, director of the Center for Environmental Health Engineering at the Biodesign Institute at ASU, all agree that this system created a scaffolding the city can use to identify other public health issues in the wastewater—from the flu to hepatitis to synthetic drugs.

“What if we saved lives?” Inchausti said. “We can be using biointelligence to keep our community safe.”

Tempe received $1 million in grant funding from the Centers for Disease Control and Prevention for its wastewater testing in August.

How it works

Halden said he approached the city of Tempe with the idea of wastewater monitoring back in 2015.

“We aren’t at the end of the pandemic, but I do think we saved a number of lives and improved the quality of life and gave actionable information—not just used by the city but by stakeholders, parents sending their kids to school,” Halden said.

ASU acts as Tempe’s lab in this endeavor. The Tempe public works team collects the samples and takes them to the university where they are tested by Halden’s team. The results are then delivered to the city where the data is uploaded onto Tempe’s open-access dashboard.

“Following the tried-and-proven approach of excreta testing of people—the way people do it individually at a doctor’s office with a urine or stool or saliva sample—we, in essence, do the same thing,” Halden said. “The same assays that apply to them apply to human waste of a larger population. That municipal wastewater runs under our feet, I think of it as like a hidden internet where information about everything that happens in the city arrives and is all swimming in the wastewater.”

The city collects a pound or two of liquid, Halden said. That water, he said, does not just include waste but includes water run from dishwashers and washing machines and showers. The liquid is also in no way traceable to a single residence or business—that is why the city operates in zones with this data, Halden said.

When the sample gets to ASU, the team checks the temperature and physical measurements, and then it extracts virus particles and genetic information of the virus, Halden said. Every virus carries a genome, and the virus genomes help the scientists determine how many virus pockets there are per liter of wastewater. A genome is a genetic set of instructions within an organism.

“It’s important that when people look at wastewater they realize it’s capturing everyone—the people who are asymptomatic and haven’t been tested and those who feel sick,” Halden said. “Clinical sampling of sick individuals alone doesn’t capture the full picture. Wastewater is helpful in measuring symptomatic and asymptomatic people.”

What the future may hold

Amy Kirby, an environmental microbiologist and the head of the CDC’s National Wastewater Surveillance System, said a system just like the one in Tempe is now in 37 states with over 900 sampling locations reporting data. The NWSS was officially established in September 2020, Kirby said.

Kirby said that each of the sampling locations were met with some skepticism, as was the case in Tempe in 2018. Inchausti said the city held a series of public meetings and, with the ability to show data, people got on board.

“In general, there’s some skepticism about tracking any kind of infection through wastewater,” Kirby said. “We have to do a lot of meetings with health departments and utilities and really explain what we are measuring and how that data can be used. It’s often the most powerful to show them data from their own community; that more often than not convinces them this is a worthwhile thing to do to keep the community safe.”

Kirby said this idea of tracking disease in wastewater is not new, that it has been used for decades to track polio overseas. However, it was not something public health officials have been able to scale in the United States.

“It’s expensive, frankly, to build this system,” Kirby said. “We needed to have a good return on that investment. Now that we have this, we can leverage it for a whole range—expanding to other public health concerns.”

Kirby said that at the end of this year the CDC is looking to begin testing for antibiotic-resistant illness; food-borne illness; and respiratory illness, such as influenza, in addition to an emerging fungal pathogen in the NWSS. The CDC will be putting in an advisory committee to help determine what it should be testing for in the future.

“Really, it’s going to be a constant process of asking what else we can be looking for,” Kirby said. “There’s potential for using it for pharmaceuticals and illicit substances in the future as well.”

Tempe City Council Member Joel Navarro was a champion of the wastewater surveillance system when it first began and the city was testing for opioids. Navarro, who also serves as deputy chief of operations with the Phoenix Fire Department, saw firsthand the impacts of the opioid crisis.

“Seeing where upticks were happening—that’s great information to have,” Navarro said. “With COVID-19 aside, I think we are going to get back to focusing on opioids and trying to get things into the schools, especially hitting sixth grade. ... What we have done in Tempe has really opened the door for other cities to follow us.”

Kirby said that nationally, wastewater surveillance has the potential to allow health officials to see a new agent of concern coming—but that discovering what the next pathogen might be would be a much harder thing to do.

“When you don’t know what the pathogen is ahead of time, that’s really difficult,” Kirby said. “That’s not a priority of the CDC right now; we are making sure we stay aligned with the science and monitor anything that is generating interest.”

The CDC program is funded through 2025, Kirby said.

“This has a lot of promise,” Kirby said. “This system can be very rapidly employed in an emergency response in the wake of potential emergencies—for example a water-related emergency of a flood or hurricane. We get concerns in those cases about water-borne infections and now there’s not a lot we can do other than message to the public. But if we have a wastewater surveillance location, we can be looking for the illness for the next few months. That kind of reactivity to public health needs at the moment is really an aspect of this I am looking forward to developing further.”

Halden said he hopes in the future wastewater testing can go so far as to prevent illnesses.

“We have spent billions on cancer and drug-resistant illness, and we are working at the end of the problem when people are already sick,” Halden said. “I compare it to building more fire stations and adding fire trucks, but if you remove the fire then you can’t have fires. If we can remove the threat agents before they create adverse outcomes, we will be able to move forward [with less illness].”