Water main break study highlights correlation between material, diameter

Utah State University (USU) has published new research on water main breaks in the United States and Canada, examining break rates and related factors such as pipe material and diameter. It is the third such study conducted by USU with previous versions in 2012 and 2018.

The new study, “Water Main Break Rates in the USA and Canada: A Comprehensive Study,” surveyed more than 800 utilities and analyzed about 400,000 miles of pipe data, representing 17% of the estimated 2.3 million miles of water mains in the United States and Canada. The sample size for this study was nearly three times larger than the previous 2018 study.

According to primary researcher, Professor Steven L. Barfuss, P.E., one of the most important indicators for identifying failing pipelines is water main break rates. Pipe performance continues to be impacted by soil corrosivity, and the replacement of asbestos cement and cast iron pipe is creating a shift in predominant pipe materials.

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

“Notably, the report shows that 20% or 452,000 miles of water pipes in the United States and Canada are beyond their useful lives and need to be replaced but have not been due to lack of funds. This represents a $452 billion shortfall. In 2012, utilities reported that only 8% of installed water mains were beyond their useful lives, so this is a growing problem,” added Barfuss, who has more than 37 years of research experience at USU’s Utah Water Research Laboratory.

Some of the major findings and benchmarks include:

  • The United States and Canada experience 260,000 water main breaks annually, representing $2.6 billion in annual repair costs.
  • Utilities reported the average failure age of water pipe is 53 years. Notably, 33% of water mains are over 50 years old, representing 770,000 miles of piping.
  • In 2018, cast iron and asbestos cement together represented 41% of all installed water mains. In 2023, the combined length for these materials is 33%, a reduction of almost 8%. PVC pipe length increased by 7% and ductile iron remained approximately the same.
  • Material usage varies significantly across geographic regions, suggesting that selection of pipe materials is often based on preference.
  • A total of 86% of cast iron pipe is over 50 years old and 41% of asbestos-cement pipe is more than 50 years old.
  • The estimated average water loss to leakage is 11%.
  • Overall failure rates decreased by 20% since 2018, which seems to correlate with reduced inventory of cast iron and asbestos cement pipe, both of which have the highest break rates.
  • A reconfirmed major finding is that polyvinyl chloride (PVC) pipe has the lowest break rate when compared to cast iron, ductile iron, steel, and asbestos cement pipes.
  • Almost 86% of water pipes in the U.S. and Canada are less than 12 in. in diameter.
  • Smaller pipes (12-in. in diameter and less) fail five times more than larger pipes (14-in. and larger).

The new report references the previous two studies to analyze changes over time. In terms of pipe mileage, it is the largest study in the United States and Canada of its kind. Previous studies have been based on much smaller sample sizes and consequently may have reduced accuracy in data reporting.

View the full report, including the full set of key findings and its methodology.

Source: Utah State University

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