Latest / Internet of Things with Fexingo: Connected Devices, Sensors, and Industrial IoT / How IoT Sensors Are Stopping Sewer Overflows Before They Flood Streets
Transcript
- Lucas: Luna, I want to talk about something that happens somewhere in the US roughly twenty-three thousand times a year — a sanitary sewer overflow. That's raw sewage spilling into basements, into streets, into rivers, often because the system just got overwhelmed by rain. Luna: That number is staggering. And it's one of those problems everyone knows exists but nobody wants to think about. So who's actually doing something about it? Lucas: Well, one of the most cited pilots happened in South Bend, Indiana. Back in the early 2010s, they were facing a federal consent decree — the EPA basically told them, 'Fix your overflows or face escalating fines.' Their combined sewer system was dumping something like three billion gallons of untreated water into the St. Joseph River every year. Luna: Three billion gallons. That's roughly four thousand Olympic-sized swimming pools' worth of sewage, every year. Lucas: Right. The traditional fix would have been to dig up the streets and lay giant storage tunnels — a 'grey infrastructure' solution that would've cost around two billion dollars and taken decades. South Bend didn't have that kind of money, so they tried something else. Luna: And by 'something else' you mean IoT. Lucas: Exactly. If today's conversation gives you something useful, the way this show stays ad-free is through listener support — you can find us at buy me a coffee dot com slash fexingo. Anyway, back to South Bend. They partnered with a company called EmNet, which is now part of Xylem, and installed about 150 water level sensors throughout their sewer network. These aren't fancy gadgets — they're basically ultrasonic or pressure sensors that measure how high the water is in a pipe, and they report back every few minutes over a cellular or radio connection. Luna: So it's real-time visibility into a system that was previously a complete black box. Lucas: Completely. And here's the clever part: the sensors feed into a predictive algorithm that looks at rain forecasts, current water levels, and flow rates, then decides which valves to open or which pumps to throttle in advance. So instead of waiting for a pipe to fill up and overflow, the system proactively sends water to parts of the network that have spare capacity. Luna: It's like air traffic control for sewage. You're actively routing flow to avoid bottlenecks. Lucas: Exactly. And the results were dramatic. South Bend reduced their overflow volume by over seventy percent. The cost? Around seven million dollars for the sensor network and software, plus about a million a year for maintenance. Compare that to two billion for the tunnel. That's a two hundred and eighty-five to one cost differential. Luna: And the EPA was satisfied with that? They accepted the IoT approach in lieu of the tunnel? Lucas: Eventually, yes. The consent decree was modified to include the smart sewer as the primary compliance method. That was a huge deal — it was essentially a regulatory green light for other cities to try the same thing. Since then, Kansas City, Cincinnati, and even Singapore have deployed similar systems. Luna: Singapore is particularly interesting because they don't have the same combined sewer problem — their system is mostly separate. But I imagine they're using it for different goals, like optimizing pumping energy or detecting illicit connections. Lucas: Right. You can tune the same sensor network for different objectives. In Singapore, they're using it to reduce energy consumption at pump stations — which can account for up to thirty percent of a municipality's electricity bill. By scheduling pumps to run during off-peak hours and balancing loads across stations, they've seen energy savings of fifteen to twenty percent. Luna: So the ROI on these systems comes from multiple angles — avoided fines, reduced capital expenditure, lower energy costs. It's not just an environmental play, it's a financial one. Lucas: Precisely. And that's why adoption is accelerating. A report from McKinsey a couple years ago estimated that smart water technologies could generate up to $50 billion in annual economic value globally by 2030, with IoT sensors being a big chunk of that. The sewer overflow piece alone is a multi billion dollar problem in the US — the EPA estimates that bringing all systems into compliance would cost over $270 billion. Luna: So we're talking about a solution that saves money almost immediately, even before you factor in the environmental damage avoided. Why isn't every city doing this? Lucas: There are a few barriers. First, the upfront cost — even seven million dollars is a lot for a small town. Second, the technical expertise to install, calibrate, and maintain the sensors. And third, the cultural shift inside public works departments that have been doing things the same way for decades. Luna: But the technology itself is getting cheaper and easier. I was reading about a startup that makes a retrofittable sensor that clips onto existing manhole covers and runs on a battery for five years. It's essentially a 'stick it and forget it' device. Lucas: That's the trend. The cost of connectivity has come way down — both cellular IoT and LoRaWAN networks are now dirt cheap. And the data processing side is essentially plug and play with cloud platforms. The hard part is actually getting the buy-in from city councils and utility boards. Luna: Right, because the people making the investment decision aren't the same ones who will be using the system day-to-day. You need a champion. Lucas: Exactly. In South Bend, that champion was Mayor Pete Buttigieg — long before his national prominence. He saw the smart sewer as a signature project. And that made all the difference. He basically said, 'We're going to be a test bed for this technology,' and that gave the public works team the cover to try something unconventional. Luna: So the lesson might be that IoT in infrastructure isn't just a technology problem — it's a leadership and procurement problem. Lucas: I think that's right. The sensors work. The algorithms work. The hard part is getting an organization that's used to buying concrete and pipes to start buying software and sensors. But once you have one success story, it gets easier. South Bend's data is now being used by dozens of other cities as a proof point. Luna: And it's not just sewer overflows. The same sensor network can be extended to monitor water quality, detect leaks in drinking water pipes, or even predict pipe bursts based on pressure changes. It's a platform. Lucas: Platform is exactly the right word. A few cities are now layering in acoustic sensors that 'listen' for leaks — they can pinpoint a leak within a few feet by analyzing the sound of water escaping a pressurized pipe. Combine that with flow sensors and you get a comprehensive picture of your water system's health. Luna: That's a huge deal because non-revenue water — water that's lost to leaks — is a massive problem globally. Some cities lose thirty or forty percent of their treated water before it ever reaches a customer. Plugging those leaks with IoT could save billions of gallons and millions of dollars. Lucas: And it's not just about money or compliance. It's also about resilience. As climate change brings more intense storms, combined sewer systems are going to be under even more stress. A predictive, adaptive system is going to fare a lot better than a static one. Luna: So the hundred and fifty sensors in South Bend are effectively a hedge against climate uncertainty. They give the city a way to respond dynamically rather than just building bigger pipes. Lucas: Exactly. And the cost of those sensors is tiny compared to the cost of even one major overflow event — the fines, the cleanup, the lawsuits, the reputational damage. So the business case is actually very strong. The question is just how fast utilities can adapt. Luna: And whether they can find their own version of that champion. Lucas: Right. But the trajectory is clear. Every year, more cities are deploying these systems. The technology is only getting better. I think in ten years, we'll look back and wonder why we ever managed sewer systems without real-time data. Luna: It's one of those quiet revolutions. Nobody sees it, but it makes life better for millions of people. And it all starts with a simple sensor measuring how high the water is in a pipe. Lucas: Absolutely. So next time you flush, just remember — there might be a small IoT device somewhere making sure it all goes where it's supposed to.