Leaky pipes cost money, as Castle Rock Water knows all too well. Serving about 87,000 residents south of Denver, the utility’s 517-mile distribution network lost 166 million gallons of potable water in 2023 alone.
This represents $400,000 to $650,000 in lost 2023 revenue, depending on how the missing water is monetized, and it’s not the worst loss that this utility has experienced, with 240 million gallons lost due to leakage in another recent year. That is equivalent to 737 acre-feet, enough to supply roughly 1,000 families with water for a year.
“The majority of our system is probably less than 25 to 30 years old,” says Matt Hayes, Castle Rock Water’s technical engineering manager. “But we do have some parts of town that have leaking cast iron pipes that are reaching the end of their service life, which are due to be rehabilitated or replaced in years to come. We also have some leaks due to issues with fittings and valves, plus ‘hot soils’ that can cause pipes to corrode prematurely.”
To address the issue, Castle Rock Water is turning to artificial intelligence. In fact, it is wrapping up a six-month trial of Digital Water Solutions’ hydrant.AI leak detection system. Under the hydrant.AI system, acoustical loggers (which are essentially underwater microphones) are installed at the bottom of a set of fire hydrants. During the nighttime hours when water usage is low, the hydrophones transmit acoustic vibrational pressure and temperature data.
“The AI technology learns what the normal sound of the system sounds like and knows what leaks sound like,” Hayes says. “So, it basically is listening for those leaks.”
Of course, the sound of a leak will vary in volume and clarity depending on its distance from the hydrophone. That’s the genius of the hydrant.AI model: By locating hydrophones in a number of hydrants spread over a large area, the location of the leak can be triangulated. This makes finding it faster and easier, while allowing for quicker and more accurate repairs.
A new Al leak detector, part of the hydrant.AI system, installed on one of Castle Rock’s hydrants.
Setting the stage
To understand the impact of leaks on Castle Rock Water, one must first understand its responsibilities. As the municipally owned water provider for the town of Castle Rock, this utility handles drinking water treatment and delivery, wastewater collection and treatment, and stormwater management. Entirely funded by user fees, Castle Rock Water has more than $770 million in infrastructure. This includes six water treatment plants and 900 miles of water and sewer lines serving a population of about 87,000.
The town’s main water treatment facility is the Plum Creek Water Purification Plant, which produces about 6 million gallons of potable water daily. Currently, its primary water sources are renewable surface water and reusable surface and ground water. This plant was built in 2013, under the town’s plan to utilize 100% renewable water by 2065.
In total, Castle Rock Water’s six water treatment plants can produce up to about 27 mgd of potable water during summer irrigation season but produce on average around 8 mgd.
A Castle Rock crew excavates sand and sediment from a raw water diverter and the catch tank where raw water is diverted to containment reservoirs.
The trial
Castle Rock Water conducted a $90,000 pilot study of the hydrant.AI leak detection system from April to October 2025. To evaluate the system’s effectiveness, the utility installed eight acoustic loggers in fire hydrants across the town’s Cobblestone Ranch neighborhood.
Being a newer area, Cobblestone Ranch doesn’t have the same level of leaks that other parts of the town’s water system have.
So why test the hydrant.AI leak detection system here? “Because Cobblestone Ranch was probably the most challenging area we could come up with,” Hayes says. “We wanted to see how well hydrant.AI performed with PVC pipes because PVC is a softer material than ductile or cast iron that doesn’t transmit sound as well. It’s like when you go into a restaurant with a hard floor where the sound is really loud and bounces around while sound in a carpeted restaurant is quieter and gets absorbed to some extent. The same is true about cast iron pipes compared to PVC. If the hydrant.AI system works in a PVC-piped system, it will work fine in a ductile or cast iron environment.”
The only downside to testing in Cobblestone Ranch is that Castle Rock Water doesn’t know if there are any water main leaks in this area. “This is why we worked with the manufacturer to come up with a testing approach,” Hayes says. “Under this approach, our guys have been flowing some hydrants to simulate a leak in order to test the hydrant.AI system and make sure it’s working.”
One further challenge: “We implemented the pilot study right when irrigation season started for us,” Hayes says. “Our utility requirements dictate that people irrigate overnight, so the hydrant.AI system has been listening for sounds right in the middle of irrigation this summer. As a result, it was a challenge to get the kind of baseline data we’ve been seeking. Still, hydrant.AI pinpointed where the heavy overnight irrigation was occurring — namely large parks and big residential systems.”
Expected benefits
Castle Rock Water just finished its hydrant.AI pilot study, but given the technology’s performance in other water distribution systems, Matthew Hayes expects hydrant.AI to pass this test, be deployed in Castle Rock on a full-time basis and eventually provide his utility with some significant benefits.
As well, the data being generated by hydrant.AI can be integrated with readings from Castle Rock Water’s existing measurement devices. “For example, we have a single line going into Cobblestone Ranch so we can compare and cross-reference the data from its water meter with the information generated by the acoustical loggers,” says Hayes. “We also like the fact that the loggers are installed in the water column at the bottom of hydrants. This means we can leave them in place year-round without worrying about winter freezing, giving us access to continuous 24/7 data.”
The biggest benefit that Castle Rock Water hopes to achieve by deploying hydrant.AI is moving from reactive to proactive system repairs.
“Water pipe breaks typically don’t happen at the convenient times. They seem to occur overnight, on weekends and during holidays,” Hayes says. “By using hydrant.AI to detect leaks before they come to the surface, our operations staff will be able to plan a proactive response to be executed during business hours as opposed to being reactive to a pipe break at the worst possible time. As well, we’re hoping to catch some of these leaks before they become catastrophic — the kind that blow up a road and put a lot of people out of service. If we can catch those early, it’s going to be a benefit.”
Hayes has one final hope associated with deploying hydrant.AI, namely not losing 160 million gallons of precious water in dry, thirsty Colorado.
“We see saving a great amount of water from wastage through better leak detection and faster repair,” he notes. “Out west, water is kind of scarce. If we can reduce losses through better leak management, that’s effectively a new source of water for our residents that we don’t have to bring in from elsewhere. If the six-month trial results prove to be positive and we are able to deploy hydrant.AI in Castle Rock, this is a positive result that is within reach.”