A study of water mains in the U.S. and Canada shows a 27 percent increase in breaks and failures during the last six years.
That's 14 breaks a year for every 100 miles of pipe — up from 11 breaks in 2012, which is the last time the study was done by the Buried Structure Laboratory at Utah State University.
The findings are another reminder that North America's water infrastructure is deteriorating, according to the lead researcher, Steven Folkman, who oversees the lab and wrote "Water Main Break Rates in the USA and Canada: A Comprehensive Study."
Water mains carry treated drinking water to the service lines of customers' houses and businesses. About 91 percent are made of asbestos cement, cast iron, ductile iron and PVC.
While the American Society of Civil Engineers raised the grade for drinking water and waste water infrastructure from a D- in 2009 to a D in 2017, Folkman said his assessment of data from 308 utilities with 197,866 miles of pipe indicates otherwise.
"There's a notion that we're getting better in terms of water infrastructure, and this study says things aren't improving. This study shows we're heading more toward an F and it's a cause for concern," Folkman said in a phone interview. "Break rates are increasing, not decreasing. That's my foremost important conclusion."
Of the survey participants, 281 utilities provided data about 23,803 water main breaks involving 170,569 miles of pipe, which represents 12.9 percent of the total length of water mains in the U.S. and Canada and is "statistically significant," according to the study.
The causes of the pipe failures were cited as circular cracks (56 percent), corrosion (28 percent), longitudinal cracks (8 percent), leak at joints (2 percent), fatigue (1 percent) and other reasons (4 percent).
The survey responses also put the national rate of water main replacement at 125 years while the study says the replacement schedule should be more like 60-100 years.
"That's inadequate, and that's why things are getting worse," Folkman said.
It's time to pay the piper, so to speak. But the projected cost is at least $1 trillion to upgrade U.S. water infrastructure to meet the needs of a growing population over the next 25 years, according to a March 2016 report by the American Water Works Association.
"It all comes back to money," said Folkman, a professional registered engineer and member of the AWWA.
As utilities and cities look for the most prudent ways to update drinking water systems, Folkman points to another major finding that was reconfirmed from 2012: PVC pipe has the lowest overall break rate.
The study defined a water main break as an incident where a leak was detected and a repair was made. The need to repair leaking cast iron and asbestos concrete pipes, which comprise about 41 percent of the installed water mains in North America, was up about 45 percent in the last six years as those pipes come to the end of their useful lives, the study says.
Potable water pipes aren't made of cast iron and asbestos concrete anymore. Ductile iron pipes started to replace cast iron after World War II, and installations increased in the late 1950s and early 1960s while the use of PVC pipes picked up in the early 1970s, Folkman said.
The data from study participants puts the failure rate of ductile iron water mains at 5.5 breaks per 100 miles, which is up 13 percent from 2012, and 2.3 breaks per 100 miles for PVC water mains, which is down 10 percent.
"PVC has a good track record right now," Folkman said.
He also acknowledged, "There is more ductile iron out there. Could that be influencing the rate? Absolutely. We tried to look at that. It's a complicated issue for sure."