Red plastic caps have appeared on fire hydrants in the Blue Ridge and Fritz Terrace neighborhoods in Bloomington.

The bright red devices, called “SmartCaps,” are part of a pilot program by the city’s utilities to find water leaks. They attach to the primary outlet on a fire hydrant and don’t get in the way of firefighting.

The SmartCaps work by listening to and analyzing sounds coming through the barrel of the hydrant all the way down to the water column.

“They're picking up distances and sounds that they're all reading together and trying to say whether there's a leak in this spot or that spot,” said James Hall, the Assistant Director of Transmission and Distribution for the City of Bloomington Utilities.

Hall said that it can be difficult to detect leaks in the water distribution line, which can cost both the utility and consumers.

“If we're making a million gallons of water a day, and we're losing so much of it, then it's uncaptured revenue - which makes everybody else kind of pay more for water that's never been used before,” Hall said.

The City of Bloomington Utilities previously used another listening device called hydrant.AI, which required more physical manual labor to install. The SmartCaps are more quickly installed.

Hall said that the caps work better with metal pipes, which is why Blue Ridge and Fritz Terrace were chosen as piloting locations.

The pilot program lasts for two months, and the utilities department will consider adding more if the program goes well. Funding for the program comes from the utility’s general water fund, which is paid for by city ratepayers.