Part of the Leisure Centre in Maple Ridge was closed Friday after part of a storm drain pipe fell down and landed near the teaching pool that morning.
Another section of the cast-iron drain pipe smashed down nearby along a wall.
Corroded brackets are blamed for the incident, which occurred in the early hours of the day.
Staff discovered the failure when the centre opened at 5:30 a.m.
"It's certainly fortunate that it happened in evening, eliminated any risk to any individuals," said recreation general manager Kelly Swift.
The corroded brackets weren't visible to inspection because the pipes were wrapped in insulation. The pipes drain water from the roof into the sewer system.
The area in which the pipes fell was part of the Leisure Centre expansion in 2000. Only the pipes in that section were insulated, Swift said.
"It looks like the problem would be isolated to that area. That was the only area that had insulation on it, which clearly covered up the brackets that were corroding," she added.
"It was really unfortunate that was something that was not visible."
No other parts of the pool pose a similar risk, and Swift said the centre will re-open as soon as possible, after an engineering inspection.
The Leisure Centre is about to undergo a $5-million refit and repair, mainly to the water treatment and circulation systems.
The failing pipe has nothing to do with the planned works.
The Leisure Centre is 34 years old and is well maintained in excellent condition, Swift said.
"The building itself is very safe. It's very unusual. It's a hidden issue that we weren't able to see."