The Art and Science of Detecting Hidden Leaks

Learn how Pittsburgh Water’s Leak Detection team works to identify, locate, and repair hidden leaks in our system.
A man in a hooded jacket, hard hat, and reflective safety vest applies corded electronic tools to the surface of an open water pipe in a neighborhood street.

In a city like Pittsburgh, where much of our water infrastructure has been in place for decades, it’s possible for leaks to form almost anywhere. Our hilly terrain, yearly freeze‑thaw cycles, and shifting hillsides can add to that potential. These and other environmental pressures can stress pipes, joints, and fittings, sometimes causing breaks that are visible right away, and other times creating slow, hidden leaks that can go undetected at first.

Hidden leaks such as these can waste a significant amount of water, lead to localized ponding in streets, yards, and sidewalks, and can lead to much bigger problems the longer they go unnoticed (like sinkholes, for example)! Not to mention, a covert leak could even drive up your household water bill if it occurs on the customer’s side of the water meter.

That’s why our Field Operations Department’s Leak Detection Team relies on advanced technology to identify leaks early.

How Leak Detection Works

Step 1: Automated “Listening” Equipment

A blue disc surrounded by a rusted metallic disc in a street surface, which is a water logger as seen from the surface. A water logger as seen from the street's surface.

Across our service area, Pittsburgh Water collects data from roughly 800 water loggers. These small electronic devices are installed across our distribution system, where they record water-related data, monitor usage patterns, and “listen” for signs of leakage.

To avoid false positives, the loggers activate in the early morning hours, between 2:00 and 3:00 AM, when the city is at its quietest and water usage is at a minimum.

If a logger detects any sounds or other water usage anomalies that might indicate the presence of a leak, the device sends an alert to our Field Operations Team with the general location to investigate. Further tests can then be conducted by our field team.

Step 2: Pinpointing the Location

Once at the site of the potential leak, our team begins by collecting as much data as possible. When listening for signs of a leak, it’s important that the team has an accurate understanding of the infrastructure they are examining, including the length and diameter of a given pipe or service line and the material it’s made of. These and other variables affect how sound travels and can impact the accuracy of our equipment. The team cross-references internal infrastructure maps, visible valves, and existing records to gather this information.

We then deploy two pieces of equipment – a specialized headset device known as an acoustic leak noise correlator, and an Automated Filtering Intelligence System (AFIS) – to help pinpoint the exact location of the leak.

Digital screen showing an active readout of test results AFIS device recording results.

The AFIS and the correlator are designed to work together to parse raw data and point our team in the direction where the leak is located.

To determine if the leak is on the public or private side of a particular water service line, the team will turn off the valve to the home and use their equipment to listen for the leak. If the noise is no longer present, this is a clear indication that the leak is on the customer’s side. If the noise continues, we can assume the leak is on the public side.

Step 3: Repairing the Leak

If we’re confident the leak is on the public side, we will continue using this acoustic-based technology to further close in on the source of the leak until it can be positively detected and excavated for repair. The team uses a ground microphone every two feet, listening for when the noise is the loudest, to accurately pinpoint the location of the leak. Finally, the team will mark the street with spray paint and indicate the affected area, so excavation crews know where to dig to repair the leak.

If, on the other hand, we confirm the presence of a leak on the private side, we’ll then hand the project over to the homeowner, as customers are responsible for their own private side service line. In this scenario, the customer will need to arrange for a plumber to address the leak, which is typically not covered by a basic homeowner's insurance plan (fortunately, water, sewer, and in-home plumbing protection plans do exist - like the ones offered through our partnership with Oncourse Home Solutions). Once complete, the homeowner is asked to notify Pittsburgh Water so that our team can make a record of the issue having been resolved.

Contacting Pittsburgh Water

If you’re concerned there may be a hidden leak on your street or on your property, please contact our Dispatch team by calling 412-255-2423 (option 1). For any other questions or concerns, please also feel free to reach out to our Customer Service team at pgh2o.com/report-an-issue!