Study: U.S. Water Pipeline Failures Cause for Concern

Utah State University’s (USU) Buried Structures Laboratory has published a second comprehensive study on break rates of the most commonly used water pipe materials titled, “Water Main Break Rates In the USA and Canada: A Comprehensive Study.”

According to the study, break rates have increased 27% in the past six years.  In particular, break rates for cast iron and asbestos cement pipes, which together represent almost half of the installed water mains in North America, have increased 46% and 43%, respectively, since 2012.

Other key findings include:

• Smaller municipal utilities have twice the water main break rates as larger utilities.
• An average of 0.8% of installed pipe is replaced each year across the country, equating to a 125-year national pipe replacement schedule.  Pipe replacement rates should be between 1% and 1.6%, equivalent to 100-year and 60-year replacement schedules, respectively.
• Polyvinyl chloride (PVC) pipe has the lowest overall break rate when compared to cast iron, ductile iron, concrete, steel and asbestos cement pipes.
• Corrosion is a major cause of water main breaks with 75% of all utilities reporting corrosive soil conditions. Cast iron pipe in a high corrosion soil has over 20 times the break rate than one in a low corrosion environment. Similarly, ductile iron pipe in a high corrosion soil has over 10 times the break rate than one in a low corrosion soil.
• Since 2012, the percentage of installed water mains which are beyond their useful lives has doubled from 8% to 16%.
• Cast iron pipes represent the largest pipe material inventory and 82% of them are over 50 years old
• Construction-related failures were equivalent for both PVC and ductile iron pipes, pointing to the need to improve construction practices for underground infrastructure regarding installation, location services and inspection.
• A national drop in average supply pressure to 69 psi (from 77 psi in 2012), which is well below the maximum operating pressure of water mains, extending pipe life as well as reducing leaks and breaks.
• Estimated average water loss due to leakage is 10%, showing that pressure reduction, leak detection and pipe replacement have contributed to reducing water loss in water distribution systems.

The study was conducted by Dr. Steven Folkman, co-author of Buried Pipe Design and author of a 2012 USU water main break report. More than 300 utilities participated, representing approximately 200,000 miles of installed water mains in the U.S. and Canada.

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