“The pump itself blew and resulted in the roof collapsing,” city water and sanitation department spokesman Farouk Robertson said.
“There is no danger to the public and the incident should not affect servicing to residents.”
It was not known if anyone was injured. The incident happened at 7am on Monday.
Robertson said it was presumed the explosion was caused by a build-up of gasses.
“There are a number of things which can contribute to such a build-up of gasses, including highly volatile matter entering the system due to sewer processes, or the dumping of illegal matter,” he said.
“It is possible that this may result in untreated effluent getting into waterways.”
To counter this, the city would use bio-augmentation to cleanse the water.