New Study Explores Water Main Break Rates in North America

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. Photo by Getty Images.

In early 2024, Utah State University (USU) (Logan, Utah, USA) published its third extensive study of commonly used waterpipe materials. The latest update is titled, “Water Main Break Rates in the USA and Canada: A Comprehensive Study.” 

According to USU officials, this comprehensive study contributes to the continuing efforts of the Aging Water Infrastructure (AWI) research of the U.S. Environmental Protection Agency (EPA). 

It also contributes to the U.S. Conference of Mayors’ Water Council, as well as the asset management and water infrastructure condition assessment efforts of the American Water Works Association (AWWA) and American Society of Civil Engineers (ASCE).

Aging U.S. Infrastructure

According to Steven L. Barfuss, P.E., a USU professor and the study’s primary researcher, 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,” Barfuss says. “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.”

Details of the Data Set

Over 800 utilities were surveyed and almost 400,000 miles (643,737.6 km) of pipe data were analyzed, representing 17% of the estimated 2.3 million miles (3.7 million km) of water mains in the United States and Canada. This data set is large enough to provide accurate information on the characteristics of aging pipe infrastructure and the costs of repair and replacement.

“Notably, the report shows that 20%, or 452,000 miles (727,423.5 km), 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,” Barfuss adds. “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.”

USU published similar studies in 2012 and 2018, and the 2023 report references the previous studies to analyze changes over time. The sample size for this study is almost three times larger than the previous 2018 water main break survey. 

In terms of pipe mileage, this is the largest study in the United States and Canada of its kind, according to USU. Previous studies have been based on much smaller sample sizes and, consequently, may have reduced accuracy in data reporting.

Major Findings and Benchmarks

According to USU, major findings and benchmarks from the latest study are as follows:

  • 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 (1.2 million km) 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%. Polyvinyl chloride (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 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 United States and Canada are less than 12 inches (30.5 cm) in diameter.
  • Smaller pipes (12 inches in diameter and less) fail five times more than larger pipes (14 inches, or 35.6 cm, and larger).
  • A total of 75% of utilities reported corrosive soil conditions, which is consistent with the 2012 and 2018 USU studies. This demonstrates the importance of corrosion mitigation for water pipelines.
  • Ductile iron pipe has over six times more failures in highly corrosive soils compared to low corrosive soils.
  • The percentage of utilities approving ductile iron has decreased by 8%, going from 86% in 2018 to 78% in 2023. Steel pipe has shown a 6% increase in acceptance, rising from 38% to 44%. Acceptance rates for other pipe materials have remained about the same.
  • Almost 44% of utilities conduct some form of regular condition assessment of their water mains.

The latest USU study did not capture or break out the inventory of thicker-walled, iron-based pipe, cathodic protection, or polywrap. Break rates associated with corrosive soils included all reported iron-based pipe, which likely had protection or thicker walls in the sampling, according to the researchers.

A copy of the full USU report, including the complete set of key findings and its methodology, can be downloaded here

Source: Utah State University,  

Related Articles