The technologies changing the deepest depths of the city—the sewer

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Sewage has a long and storied history worldwide, from Mesopotamian clay pipes and Roman baths drainage to the 1.3 million miles of US sewer systems operating today. Popularized in the 1920s and revamped in the ’70s, stateside sewer systems haven’t changed all that much in the past four decades.

That is, until now.

Sewers are getting the high-tech treatment in cities ranging from Salt Lake City to South Bend, Indiana, thanks to an emerging crop of tech and science startups helping detect area pathogens, offload unnecessary cleaning for public works teams, and even avert sewer flooding. It’s all part of a growing trend of cities investing billions to modernize sewage systems.

We’ve broken down three of the key technologies that cities are plunging into their deepest depths.

Disease detection

Wastewater surveillance—i.e., testing sewage for pathogens—isn’t new, but in the Covid era, the tech has received more attention for its ability to monitor virus levels in localized areas.

Ginkgo Bioworks, a Boston-based synthetic biology company, wants to help modernize the space with its public health and biosecurity arm, called Concentric.

Much like anomaly detection is an increasing necessity for cybersecurity, “we need the same thing for biosecurity,” Laura Bronner, head of Concentric’s wastewater programs, told us. “With the infrastructure that we set up during Covid, we can create that surveillance network, but then we can detect not only the pathogens we know about, but also the pathogens that we don’t know about.”

Bronner said Concentric’s past points of detection for wastewater include schools and assisted-living facilities, where the company used samples to test for Covid in those communities.

The company has plans to incorporate its mechanical device into a city wastewater treatment plant and take regular samples based on the amount of incoming wastewater, but it has not yet deployed them in plants. The samples it collects will then be shipped to labs, which can test for SARS-CoV-2, monkeypox, polio, or general anomalies, including unidentified pathogens.

“From there, let's say we’re collecting at 10 stops throughout the city, and we’re collecting three times a week—you now have 30 data points per week in that city for all of these different pathogens,” Bronner said, adding, “Just like you would in any data set, you would look at the trends over time…From there, you can start to create predictive tools.”

Concentric is a little over two years old, and since its debut, it has mostly specialized in Covid testing. Around the time monkeypox started making headlines, the team began ramping up its goal to test for pathogens besides SARS-CoV-2, Bronner said. The big sell for cities and schools, per Bronner, is being able to better track how a virus or pathogen spreads through the community—and being able to adjust procedures accordingly if an outbreak begins.

Singing for your sewer

An increasing number of US cities are using sound science to assess blockages in sewers by way of an acoustic device called the SL-RAT.

Here’s how it works: Open up two neighboring maintenance holes, and place the SL-RAT’s transmitter in one, and the receiver in the other. During a three-minute assessment, the transmitter sends sound waves down the pipes, and the receiver picks them up. If the sound signal stays completely intact, the pipe is clear; if it’s garbled, there may be a blockage.

The SL-RAT device itself isn’t so new—it’s been manufactured by InfoSense since 2012—but since 2019, it’s found new popularity through a partnership between InfoSense and RH Borden, an Ohio-based wastewater management tech company. In 2019, RH Borden set up a service company to harvest the device’s data in the field and put it into a clickable map, enabling cities to focus resources elsewhere, according to founder Jon Borden. Since then, he added, 129 cities have signed on to use the acoustic tech, ranging from major hubs like Salt Lake City to smaller cities of about 5,000 residents.

“It’s a new technology; it’s addressing a problem that we’ve had for a long time, since sewers were being cleaned by jet trucks,” Borden told us, adding that starting in the 1950s, jet trucks were typically used to clean all the lines in a sewer system—but, since just 11% of sewer lines are in poor or blocked condition in any given year, according to data shared by RH Borden with Emerging Tech Brew, the process of cleaning all lines every year can waste water and city resources.”

“Our company is currently in the west, and there’s a megadrought going on out here, so we’re taking perfectly good water and flushing it down the sewer unnecessarily,” Borden said. “Instead of using water, [acoustics] use sound, and they can identify very quickly which sewer lines are clean and which sewer lines are dirty.”

Flood prevention

In at least one US city, the Internet of Things has an unlikely member: maintenance-hole covers.

The covers—sold by EmNet, an Indiana-based startup that has since been purchased by Xylem—combine a sensor, microprocessor, radio, and battery to monitor flow, depth, velocity, temperature, and more, with automated control valves to help control flow levels.

In South Bend, Indiana, where 120 of the sensors were first installed in 2008 and upgraded in 2017, they have saved the city about $1 million a year in operations and maintenance costs and millions more in avoided penalties, Tim Braun, VP of enterprise solutions at Xylem, confirmed. The city also plans to build storage tanks for sewer overflows, but due in part to more accurate sensor data, as of February 2022, the planned spending for those tanks had dropped from $713 million to $276 million, according to Braun and Municipal Sewer and Water Magazine.

“The success we’ve had will allow us to build smaller and fewer tanks than we thought we would need,” Richard Radcliff, combined sewer overflow operations manager for the South Bend (Indiana) Wastewater Department, told MSW Magazine in February. “Sensors brought light to the collection system and allowed us to find blockages, find I&I, and find problems. Sensors gave us a better focus on where the problems are.”

In South Bend, Xylem’s system also reportedly reduced combined sewer overflows by as much as 80% in recent years, Bullen told Emerging Tech Brew, adding that the technology is now used in “dozens of cities across North America and Europe.”

“If someone asked me to manage a system that didn’t have sensors, I’d say it’s all but impossible,” Radcliff told MSW Magazine. “I don’t know how you could manage a collection system without a sensor network. You’d just be blind. You’d never be able to quantify the effect of the changes you make.”

Update: This piece was updated 11/4 to clarify where Concentric's technology is currently deployed.