Water is a precious commodity, particularly in an era of climate change. Yet, a thirsty America is entrusting it to an aging, network of leaky pipes.
“Much of our drinking water infrastructure is nearing the end of its useful life. There are an estimated 240,000 water main breaks per year in the United States,” notes the American Society of Civil Engineers in its 2013 Report Card for America’s Infrastructure. Overall, the organization gave a grade of D to our drinking water infrastructure.
By some estimates, between 15 and 20 percent of all water pumped in the U.S. never reaches the tap. The number can be as high as 60 percent in some municipalities, according to the Environmental Protection Agency (EPA). Globally, an estimated 12 billion gallons are lost each day.
Most leaks are traced to small-diameter pipes. It’s the 5 percent of leaks that occur in large-diameter pipes that account for more than half of all lost water, or “non-revenue water” as it is sometimes called, according to the American Water Works Association,
We can hardly afford the $1 trillion it would take to replace all those pipes, but we can ramp up our efforts to detect and repair leaks as rapidly as possible.
That’s what the folks at the Birmingham (Ala.) Water Works Board (BWWB) are doing. The utility operates the largest water system in Alabama, serving approximately 600,000 customers in 33 municipalities. They maintain 3,900 miles of pipe and pump 102 million gallons per day.
The BWWB ran a successful leak detection program last year on 7.7 miles of 42-in reinforced concrete pipe that ran from their Shades Mountain Filter plant to various areas of the city. The pipeline, which was built in 1927, operates between 60 and 90 psi. The program involved a series of three inspections which located 26 leaks of varying size.
The utility worked with consulting firm Pure Technologies, which utilized the SmartBall in-line acoustic leak detection technology. The device allows the pipeline to remain in service during the tests. The instrument-filled ball, containing an acoustic sensor, is inserted into the pipeline and tracked as it moves, “bringing the sensor to the sound.” The technique has found an average of 2.2 leaks per mile, according to the company.
Receivers are placed at specific locations to track the progress of the ball as it makes its way along the pipeline. Leaks can usually be detected within 10 ft of their actual locations.
In BWWB’s test, they found leaks ranging from 1 gallon per minute to 15 gallons per minute. The larger leaks were quickly repaired.
Finding and fixing small leaks might prove to be the most cost-effective way of reducing water loss in the long run, according to Stephen Rothwell of Pure Technologies.
Large leaks take a long time to develop. By the time they occur, the pipe is near the end of its life and should be replaced. But small leaks will grow into large leaks. So, the reasoning goes, if leaks are fixed when they are small, there won’t be any large leaks. Not to mention the fact that by the time a leak has become large, decades of water loss has occurred.