AI Tool Uses Sound Waves to Detect and Repair Leaky Water Pipes

In the battle to conserve water, leaking pipes form an insidious enemy, accounting for average losses of 30 percent – but in some localities as much as 70 percent – of piped drinking water across the world. The leaks can be very difficult to pinpoint, but a new AI tool is making the process faster and more accurate.

A white X marks a leaking fire hydrant in the San Tan water district, just southeast of metropolitan Phoenix. The leak is a medium one of three to seven gallons per minute. That adds up quickly, with each day of leaking equivalent to the average water consumption of 43 households.

In this case, the typical giveaways of a leak aren’t present – no puddles, no unexpected greenery in the desert landscape, no caved-in street. The water has been seeping away through the bottom of the hydrant.

“That’s something that probably most likely would have leaked until the next fire hydrant maintenance cycle, which could be up to five years,” says Jacob Rogers, division director at EPCOR, the biggest private water utility in Arizona.

But this leak was detected sooner, thanks to an AI acoustic tool developed by FIDO Tech, whose technology not only detects leaks more precisely to their location, but also ranks them by size so that utilities can prioritize which to repair first. Oxford, U.K.-based FIDO is working with several utilities, such as EPCOR in Arizona and the State Water Commission in Querétaro, Mexico, as part of a Microsoft program to act responsibly by replenishing water in the same watersheds around the world where it has operations, including datacenters.

Leaks waste more than water

Stopping municipal water leaks prevents waste and increases water availability for the customers and communities that a utility serves. For the communities involved, leaks represent not only lost water, but also the cost of pumping it, of transporting it – which requires huge pipes and tremendous energy to push it, because it’s very heavy – of filtering it and of the chemicals needed to treat it. This lost water is called non-revenue water because it never arrives at a paying customer. Instead, everybody foots the bill.

“We’ve acquired troubled utilities in Arizona that had 30 to 40 percent water loss,” says Shawn Bradford, senior vice president of regulated water in Arizona and New Mexico for EPCOR, which has been working with FIDO under Microsoft’s program for about a year. “We’re having to pump 40 percent more water than they need just to cover the leaks that it takes to get it from the well or the water treatment plant to homes, and that’s a tremendous cost that all customers face.”

EPCOR has cut non-revenue water to around 10 percent from 27 percent, in part thanks to FIDO. FIDO provides sensors that are placed so they touch a pipe, whether that’s on top of an easily accessible pipe, on a hydrant, in a valve chamber or on a tap, FIDO’s Edwards says. EPCOR has 4,554 such sensors on its pipe network in the 160-square-mile San Tan service area. The sensors record everything, even the lowest, quietest noises.

“Sound propagates differently in different materials, just like it does in a school orchestra. You know, the longer the trombone, the longer the pipe, the deeper the sound compared to the trumpet, with shorter length and higher frequency. The largest leaks are the quietest – the human ear cannot hear them – especially in a plastic pipe,” Edwards says.

Utilities have long relied on acoustic devices to detect leaks. FIDO’s technology goes a step further, running the data its sensors have collected through a deep-learning AI tool that has learned to accurately determine whether a noise is caused by a leak or something else, like machinery or a train rumbling by. It can also assess how big the leak is and pinpoint its location. The other benefit of FIDO’s technology is that utilities’ technicians can easily interact with the AI in natural language.

EPCOR, too, had used acoustic leak detectors elsewhere, but “you have to spend a lot of time trying to figure out exactly where between those two devices the leak is actually located,” Bradford says. “The benefit of FIDO is it takes all that raw data and runs it through AI to help pinpoint where the leak is. FIDO in particular can do this on plastic pipe, which has always been a challenge for the industry – the leak doesn’t resonate like it does in metal pipe.”

The lack of resonance in plastic pipes means many acoustic leak detectors struggle. Yet most new pipe infrastructure is plastic, or PVC, because it’s lighter and easier to maneuver, making it easier to install and repair. On top of that, plastic pipe is better suited to the soil chemistry in the southwestern U.S., Bradford says, and dominates in the San Tan Valley, which has developed in the past three decades and continues to be among the fastest-growing U.S. communities. The utility does also have metal pipes – some are 60 to 70 years old and still in top condition. Pipes can break for many reasons besides age – for example, shifts in the ground from freeze-thaw cycles. In fast-growing San Tan, the leaks tend to occur in areas under construction.

Before FIDO, the utility relied on satellite imagery to spot such giveaways as green vegetation growing in unlikely places, Rogers says. But such greenery doesn’t sprout overnight – it takes days or weeks to grow. FIDO can find leaks much more quickly.

A fast and flexible solution

The AI also analyzes the utility’s network map to advise where to place sensors to avoid deaf spots, Edwards says. Results pour in immediately. “You can leave it overnight or for years at a time,” she says. The sensors are easy to move to monitor different swathes of the pipe infrastructure.

The sensors can also be placed on either side of a leak after it’s repaired, to make sure the fix is successful, or to spot whether the digging during the repair has caused another leak. And then the sensors can be moved to start detecting in a different part of the network. Meanwhile, FIDO’s AI can assess the likely volume of the leaking water so the repair work can be prioritized for maximum impact.

The leaky hydrant marked with an X turned out to have a faulty seal, and the repair was quick. Not all leaks are fixed as easily. Repairing buried pipes may require digging holes. Precision in locating leaks is essential to avoid tearing up streets, sidewalks or yards any more than necessary. It isn’t just a matter of minimizing traffic disruption – the utility is required to repave the street after the repair, which represents a significant cost that grows with the size of the excavation.