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66 Adams Blvd.
Brantford, Ontario
66 Adams Blvd. Brantford, Ontario

Lessons Learned from Calgary’s Disastrous Water Main Break. Should HDPE Play a Bigger Role in the Future of Municipal Water Systems?

It was the worst-case scenario for the City of Calgary and the people who call it home. On Wednesday, June 5, 2024, the City’s biggest water main, the two-metre-diameter Bearspaw South Feeder, suffered a massive failure, the likes of which have never been experienced before in Calgary. Although the burst was in a single section no larger than five metres, the pipe and everything that relied on it practically ground to a halt. 


The major water main pipe, located in the Bowness neighbourhood of Calgary, connects the Bearspaw Water Treatment Plant to the rest of the city. This line is one of only two main lines that carry water into the city and “normally supplies up to 60 percent of the city’s drinking water.” 


Built of prestressed concrete cylinder pipe (PCCP), which is a special type of pipe that has a concrete core, a steel cylinder and prestressing wires, the Bearspaw was often inspected externally but was difficult to inspect internally as shutting it down for inspection was never an option. 


Reports state that the concrete couldn’t take the pressure and was deteriorating, resulting in a sudden water loss for the Bowness neighbourhood and throughout Calgary. Quickly after the disaster, the mayor declared a rare state of emergency, and the entire City wondered how this could happen.


A Massive Failure That Shook Calgary and Practically Shut It Down

The hours and days afterward weren’t a great time to be a Calgary resident nor on the teams devoted to repairing the pipe. 


The water supply in the neighbourhood was no longer available, water at six schools was shut off, and there were major water restrictions for all residents: boil water advisories, no more watering lawns, filling pools, washing windows, using dishwashers unless they were full, and even using washing machines only if absolutely needed. 


The City encouraged employees to work from home to limit water consumption and showering. Businesses were even threatened with water being shut off completely if they didn’t comply with the restrictions.


It wasn’t until six days later – June 11, 2024 – that a temporary solution in Bowness was available while the major repairs continued. A few days later, they announced more shocking weaknesses in the line that required emergency work.


Throughout this time, Calgary’s other treatment plant, Glenmore, was running at maximum capacity. Any failure there or in the system connected to it would be devastating to the largest city in Alberta, leaving most people without water.


Having sourced new two-metre pipes in San Diego, urgent repairs were completed on the feeder main, and things were starting to get back to normal. 


Except that in July, Calgary’s Montgomery neighbourhood also had a water main break. Fortunately, this wasn’t nearly as devastating since it was not on the ‘feeder main’ itself but instead on a line that’s only 10 inches in diameter, affecting 14 homes and 10 businesses.


Good news finally came in August and September 2024, as additional repair work was carried out on 21 segments along the feeder main.


As of 2025, 29 pipe segment repairs have taken place to support the stabilization of the feeder main, and the pipe has undergone a more in-depth investigation to gain an understanding of the conditions that led to the failure. It won’t be until the end of 2025 that a plan to implement recommendations will be finalized.


So Now What?

The City of Calgary had no clue this burst was going to happen. The pipe, built in 1975, was supposed to have a lifespan of 50–100 years and had been inspected and tested regularly.


Was this event an anomaly? Isn’t concrete supposed to last longer? A hydrology expert at the University of Calgary, Professor Tricia Stadnyk, says, “The average lifespan for this kind of high-pressure pipe is 50 years — right about now.”


A water expert says he’s aware of roughly 600 'catastrophic' failures with similar pipes across North America.


So although this wasn’t foreseen, it’s still a frequent occurrence and one that will continue to happen when concrete is trusted with such important roles. 


This event is a canary in a coal mine for the municipalities throughout North America that installed PCCP. More of these failures will occur as our infrastructure ages, especially the concrete pipes that were not built up to today’s standards. And it could be much, much worse.


The Lessons Learned from the 2024 Water Main Break in Calgary

Sandale Ontario knows that one of the biggest issues our municipalities face is the way large amounts of water are brought into cities using large, outdated concrete and steel pipes. 


We must acknowledge what happened in Calgary, consider our options, and proactively develop solutions.


Bigger Isn’t Always Better.

Putting all of your eggs in two baskets is risky, even in the best-case scenario. Delivering water using a larger quantity of durable, flexible and long-lasting pipes, such as HDPE pipes, could be a better solution. This will ensure if one does fail, it will not bring an entire city to a halt, as it can lean on the other pipes’ capacity without overloading the system.


Inspect Your Pipes Regularly. 

Although the City of Calgary inspects its water mains annually, using a combination of physical observations, modelling, and other methods, shutting off the entire line to do an interior inspection wasn’t an option since so much water for the City was carried through it.


More recent innovations show us that there are options for detecting the internal conditions of a pipeline with water without draining the pipe itself. In the aftermath of the incident, the City used acoustic monitoring devices that picked up more than a dozen additional wires snapping along the PCCP pipe.


Concrete Has Failed and Will Continue to Fail

Concrete is supposed to last 50–100 years, but as Calgary learned, this is purely a guess and based on incorrect modelling. 


Fortunately, only 9% of Calgary’s pipes are made of concrete, but – and this is a big but – a whopping 33% (almost 2,000 km) are made of ductile iron and cast steel.

(Courtesy of the City of Calgary)


What happened in Calgary would happen again if not for the proactive replacement of these old systems with modern and long-lasting potable water delivery systems. Canadian municipalities need to prioritize these options and put effort toward minimizing disruption.


Maintaining Water Systems is Expensive

The feeder main disaster alone cost at least $20–25 million. That doesn’t take into account the spiralling costs to maintain and inspect this vital piece of water infrastructure or the lost revenue from businesses. 


When it comes to large-diameter pipes, like feeder mains, the replacement cost will only continue to rise. 


HDPE is the Answer to Moving Pressurized Potable Water

Sandale Ontario supplies large-diameter HDPE pipes for pressure applications as high as 63". 


Here are some facts on HDPE pipes to get you going on your path of understanding alternatives to steel and concrete pipes:

  • HDPE pipe sections are heat-fused, resulting in stronger seams than the HDPE pipe itself.

  • HDPE pipes have incredible fatigue resistance.

  • HDPE pipes can withstand repetitive pressure surges.

  • Our HDPE pipes can be supplied in coils of over 1,000 feet (But larger-diameter HDPE pipes can be supplied without being coiled.)

  • HDPE pipe will not corrode.

  • History has proven that HDPE pipes have lower maintenance costs.

  • Lastly, HDPE pipes can handle significant pressure and are suitable for water systems.


Sandale also supplies profile pipes up to 132” in diameter that can be used for irrigation, hydroelectric pipe systems, storm drainage, wastewater systems, and holding tanks. Profile pipe can also be custom-fabricated into manifolds, vaults, and chambers to complement other HDPE pipe systems.


So, What are the Next Steps for Municipal Water Infrastructure Applications?


If you’re looking to learn more about how polyethylene piping materials, their physical and chemical properties and their mechanical and engineering behaviour, read the Plastics Pipe Institute’s authoritative The Plastics Pipe Institute Handbook of Polyethylene Pipe.


You can also reach out to one of our knowledgeable sales representatives. We’re here to reduce your maintenance costs, improve your system reliability, and provide a better, more durable solution for your municipality.



PHOTO CREDITS/CAPTIONS


Repair Site 1: Parkdale Blvd N.W. (Courtesy of the City of Calgary)

The area of the Bearspaw south feeder main that ruptured on June 5, showing the components of a prestressed concrete cylinder pipe (PCCP). (Courtesy of the City of Calgary)


Replacement pipe segment provided by the San Diego County Water Authority. (Courtesy of the City of Calgary)

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