Study: Water main breaks up, but PVC best performer

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."

The Ductile Iron Pipe Research Association (DIPRA), which represents ductile iron pipe manufacturers, says Folkman's study is biased and raises questions about funding and methodology.

The 2012 and 2018 studies were paid for by the Uni-Bell PVC Pipe Association, which represents PVC pipe producers and promotes their corrosion-resistant products, and the Water Finance Research Foundation, which describes its mission as finding affordable and sustainable solutions to aging infrastructure and lists no members on its website.

"It's hardly surprising that a study sponsored by Uni-Bell finds favorable results for their product, but certain changes to, and omissions in, the report raise significant questions, leaving us to wonder how they affect the data," L. Gregg Horn, vice president of technical services for DIPRA, said in a news release.

For example, the study didn't look at PVC pipe failures caused by construction damage, the tapping of service lines, and joint leaks, Horn said.

The study addresses this, saying those kinds of failures are often identified during the first year of operation and aren't indicative of pipe degradation.

"The goal was to examine pipe longevity," the study says.

DIPRA also takes issue with Folkman's conference papers and presentations to plastic pipe associations and companies as showing "a history of engagement" with the PVC pipe industry.

Folkman offered a brief and broad response to the DIPRA release.

"I'm not going to get into a tuft with them," he said. "Yes, we were funded by Uni-Bell because they think they have a good story to tell with respect to PVC pipe. There's a more important story here than what they're crabbing about."

Folkman said this is one of the largest surveys done on water main breaks, which are an important metric in managing infrastructure assets and making decisions about pipe repairs and replacements. The 308 responses came from 48 states in the U.S. and 7 out of 10 Canadian provinces. That's a 49 percent increase compared to 2012 and 45 percent more miles of pipe studied.

"When you ask people to voluntarily give data, and all they will get is a copy of the report, you worry that they will say forget it," Folkman said. "But by and large, and this is very telling, we got a lot of participation, and it's because people are interested."

The results give utility officials and policy makers insight into aging water systems and can be used as a planning tool for water delivery, Folkman said.

"Another important observation is where the problem is most acute," he added. "The study clearly shows that small utilities are having the worst problems. Break rates are more than double and it doesn't matter what pipe material you're looking at. Small utilities have the biggest backlog of pipe that needs replacing and I anticipate it comes down to money every time."

Some utilities won't even consider PVC pipes, let alone install them for water mains, but Folkman said that is changing. Seventy-four percent of survey takers allow PVC pipes, up from 60 percent in 2012, while acceptance of other materials, such as steel pipe, concrete steel cylinder and ductile iron essentially stayed the same between the studies.

"There's increasing acceptance to allow PVC but that doesn't mean they put it in," Folkman said. "The other 25 percent of utilities don't even allow PVC to bid."

Folkman said it's time for utilities to level the playing field, and perhaps lower their costs, by looking at what all materials can do for their water distribution systems and rate payers.

"One point I try to put across is that people should consider all alternatives and allow open competition, where you look for pipe with a long life and low overall cost during its lifetime," Folkman said. "Let's be open about this and have everyone put their best plan on the table and compare costs."

Regardless of the cost of the pipe material selected, rate payers benefit from the rivalry, he added.

"Where we have open competition, the bids for ductile iron go down," Folkman said. "Make people compete."