Study finds consistent break rates with aging water pipes

The U.S. and Canada experience 260,000 water main breaks every year – resulting in about $2.6 billion in annual repair costs, according to a recent study of commonly used pipe materials conducted by Utah State University.

Additionally, 20% of water pipes throughout North America have passed their useful lives, but many have not been replaced because of lack of funds, according to the study, the third published by the university since 2012. The estimated water loss caused by leakage is 11%, researchers found.

The latest report surveyed over 800 utilities and analyzed around 400,000 miles of pipe data – about 17% of the estimated 2.3 million miles of water mains in the U.S. and Canada, according to USU.

“Utilities can use this report to assist with asset management and facilitate water infrastructure planning and pipe replacement decision-making,” lead researcher Steven L. Barfuss said. “The goals are to control operating costs, reduce service level impacts, and minimize health risks to customers.”

Part of the problem is that 33% of water mains are over 50 years old, including 86% of cast-iron pipes and 41% made of asbestos cement, the study showed. The average failure age is 53 years, utilities said.

But although break rates remained consistent over the past decade, overall water main failures decreased 20% between 2018 and 2023, the study shows.

The move away from cast-iron and asbestos cement pipes to those manufactured from PVC is likely a factor in that decrease, researchers said. PVC has the lowest break rate compared with cast iron, ductile iron, steel and asbestos cement pipes.

In 2018, cast iron and asbestos cement together represented 41% of all installed water mains. By 2023, those materials accounted for 33% of mains, researchers said.

During that same period, use of PVC pipe increased by 7%, while ductile iron remained approximately the same, according to researchers.

Poor soil conditions are also an issue for utilities, with 75% reporting corrosive soil conditions. This demonstrates the importance of corrosion mitigation such as polyethylene encasement – also known as polywrap – zinc coating, bonded coatings and cathodic protection, the study said.

Another factor in failures is the size of pipes, according to the report. Smaller pipes – those 12 inches in diameter or less – fail five times more than pipes 14 inches and larger, the report found.

Almost 86% of water pipes in the U.S. and Canada are less than 12 inches in diameter –68% being 8 inches or less, while 10- to 12-inch sizes make up an additional 18%, according to the report.

Based on the Environmental Protection Agency’s estimate of 2.2 million miles of water pipe in the United States, these sizes account for approximately 1.9 million miles of pipe.

Although the “overall assessment of water infrastructure condition is not good,” researchers said, almost 70% of water utilities have a pipe replacement program, and almost 44% perform some form of regular condition assessment.

“This confirms that utilities are making a concerted effort to actively replace gaining infrastructure and failing water mains,” according to the report.

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