High-tech listening finds water leaks

In a region parched by drought, repairing even small leaks is worthwhile

Staff WritersNovember 16, 2007 

  • Facts, news, contacts at


  • Think there's a water leak in your neighborhood? Here's whom to call:

    Cary, Apex, Morrisville: 469-4090

    Durham: 560-1200

    Johnston County: 989-5075

    Orange Water and Sewer Authority: 968-4421

    Raleigh: 250-2737

Dennis James spends his working hours with an ear cocked toward the underground, listening for high-pitched whistles, static and other sounds that indicate precious water is escaping.

As Raleigh's most experienced leak detector, James, 49, combs the city's 2,000-mile underground network of water pipes with high-tech, high-priced audio equipment.

"I've got some pretty expensive toys," said James, whose arsenal includes a $45,000 electronic leak detector and an array of ultra-sensitive microphones. "No leak sounds identical to another."

With the Triangle enduring its worst drought in more than a century, leak detectors such as James have taken on new importance. On any given day, the region's public water systems say they can't account for millions of gallons of water, much of it due to leaky pipes under city streets and sidewalks.

"We have been operating pretty much in emergency mode for months," said Andy Brogden, Raleigh's water distribution superintendent and James' boss. "If we have a leak, we fix it as soon as possible."

Any public water system that keeps track of 90 percent or more of its water is considered to be in good shape, according to Wayne Munden, head of the technical services branch of the state's water supply office. Losing more than 10 percent is a problem.

"Ten to 20 percent, it's a concern," Munden said. "More than 20 percent, and you need to start looking somewhere."

The water unaccounted for -- the difference between what a utility pumps into its system and what it bills for -- can be attributed to several factors besides leaks, including fire hydrant use, routine line flushing and other official uses that are not metered.

Raleigh water managers say the city doesn't bill for about 8 percent of the water pumped through its system, though officials wouldn't estimate how much is a result of leaks.

OWASA limits leaks

For the Orange Water and Sewer Authority, the source for Chapel Hill and Carrboro, there is an 8 percent difference between the gallons billed and gallons pumped. About a quarter of that is used to flush hydrants and lines, fight fires and other official business, said John Greene, general manager of operations.

OWASA limits its losses, Greene said, by aggressively changing business and residential meters that slow with age and measure less accurately the number of gallons flowing through them. Each year, it replaces several miles of mains.

Durham's unaccounted-for water rate is higher, at 12 percent -- in part, managers say, because of aging pipes, meters and other equipment.

Cary's unaccounted-for water had hovered between 3 and 4 percent for years until it unexpectedly spiked to 17 percent this summer. Mike Bajorek, director of the town's Public Works and Utilities Department, said officials think the increase is related to Cary's merger with Morrisville's system last year.

Bajorek said he's confident the increase isn't the result of leaks in either Cary or Morrisville, as Cary has been aggressively surveying its entire system. The more likely culprits are unmetered taps, old meters that aren't working properly or meters that were never hooked up to the system.

"It's not a use issue in terms of people wasting water," Bajorek said. "It's much more of a revenue issue."

The leaks that get the most attention are visible ones, such as when a main breaks and floods a street. In Durham several weeks ago, nearly 35,000 gallons were lost when a main broke at the intersection of University Drive, Chapel Hill Road and Dixon Drive, said Vicki Westbrook, the city's deputy water manager.

Broken lines likely

As the drought persists and the ground around pipes shrivels and settles, more mains are breaking, according to system managers.

Earlier this month a 12-inch main under Avent Ferry Road in Raleigh broke and spewed thousands of gallons a minute. By the time the main was fixed, the city had lost 500,000 gallons, or 1.25 percent of the average used by the entire Raleigh system in a day.

"We were losing a lot of water there," Brogden said.

James and two other leak detectors are constantly surveying Raleigh's system to identify invisible leaks. James typically finds two to three a day. Most are small, in service lines where 30 gallons of water per minute may be lost.

The pricey technology used by James can pick up an ice-machine kicking on or the rattling of dishes in a sink; it typically pays for itself within a matter of months. Pinpointing a leak means the city has to rip up less asphalt to fix a minor problem before it becomes a much larger one.

On Thursday morning, James slipped ear-muff headphones on and dipped his microphone into a meter box under Blount Street as rain pounded the pavement.

A blast of static crackled on the headphones. The microphone had picked up a leak in a service line.

"It amazes me the things they can do," James said.

david.bracken@newsoberver.com or (919) 829-4548

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