CALGARY — A report says lax manufacturing standards more than 50 years ago and the breakdown of pipe materials likely caused the water main break that crippled Calgary's water supply last year.
The Association of Professional Engineers and Geoscientists of Alberta says there's nothing to suggest malpractice by the city led to the rupture and that it was complying with group regulations.
"No indications of unskilled practice or unprofessional conduct were found during the practice review," the association wrote in a news release Wednesday.
Calgarians were asked last June to severely limit their water use after one of the city's two main water pipes burst, flooding a street with clean water.
The city found numerous sections of pipe needed repairs, extending water restrictions into late September. At the time, Calgarians were prohibited from watering their gardens or lawns and were asked to severely limit their indoor water use.
The feeder main was expected to function for 100 years, but the report says relaxed standards around the time it was built in the 1970s may have led to the premature failure. Standards have since improved, the professional association said.
The report suggests the pipe's concrete coating generated small cracks over the years and wires around it eventually snapped.
"The design of the pipe in the 1970s, while acceptable at the time, may not have been sufficient to prevent microcracking, leading to accelerated corrosion from aggressive environmental conditions over the entire life of the pipe," the association wrote in the 596-page report.
Soil chemicals such as chloride, found in snow and ice melt, often attack the concrete and steel wires that envelop the pipe, and the authors said the city should consider sampling the soil along its key water mains -- particularly along major roadways and snow-removal routes.
The report adds that strong monitoring and predictive technologies won't prevent a rupture from happening in the future.
Calgary Mayor Jyoti Gondek said spending more to maintain Calgary's water system isn't optional and she's preparing to share an update next week on current and future improvements.
"We’re taking this seriously," she wrote in a statement.
This report by The Canadian Press was first published May 28, 2025.
Matthew Scace, The Canadian Press
