By Kristin Rehg, Project Manager, Evanston Utilities Department
Every day in the United States, we lose nearly 6 billion gallons of treated drinking water due to leaking pipes in water distribution systems. That’s over 2 trillion gallons annually, or enough to put the entire City of Chicago under 43 feet of water. To minimize Evanston’s contribution to this staggering water loss total, the City’s Utilities Department developed a City-wide surveying program to catch water main leaks early and minimize our water loss.
The Utilities Department uses leak noise loggers, small transmitters that sense the sound waves created by water escaping through a hole in a water main, to proactively test water mains for leaks throughout the year. The loggers are small enough to fit inside the water main valve boxes where they are attached to the water main to listen for leaks. Loggers are deployed in the course of a water distribution crew’s work one day and picked up the next day. In the meantime the loggers are contained below the ground surface, making them unobtrusive to motorists and pedestrians and protected from damage.
This flexibility has allowed the Utilities Department to incorporate leak surveying into the normal daily work flow with no additional employees or overtime needed. Water distribution crews were able to survey all 157 miles of Evanston’s water mains in 2013-2014. Their work identified three water main breaks and five water service leaks, several of which were running to nearby sewers and may never have been detected otherwise. These eight leaks were responsible for at least 15 million gallons per year of water loss. That’s equivalent to two full days of water consumption by Evanston’s entire population, all lost to leaks.
Water distribution crews have become so proficient in using the leak detection equipment that they anticipate being able to survey the entire 157 miles of water mains in Evanston in 2015 and each year thereafter. This frequency is important since water main breaks and leaks can develop at any time; a water main that shows no signs of leakage one year can develop a large leak by the next year.
In summary, the leak detection program has been a definite success and has empowered Utilities Department staff to take a greater personal interest in reducing water loss.