A leak in the City of Hamilton’s sewage system that went undetected for 26 years dumped as much as 337 million litres of waste into the Hamilton Harbour, the city confirmed Monday.

The leak was initially discovered just after 12 p.m. on Nov. 22 at the northeast corner of Wentworth Street North and Burlington Street East, officials said in a release.

According to the city, it went undetected since 1996.

A hole in a combined sewage pipe was found to have caused the leak, they said, and as a result, 50 or so Hamilton residences have been flushing directly into a storm sewer leading into the harbour.

In total, the city estimates repairs will cost $29,830 – $17,000 for realignment of the sewer, $9,830 for onsite vacuuming of combined wastewater, and $3,000 for road restoration.

Much of that work has already been completed, the city says.

"The repair work and realignment of the sewer was completed on Nov. 23 at 9:32 pm, and all sewage is now flowing into the Western Sanitary Interceptor and all appropriate repairs to the combined sewer have been completed," it said in a statement issued Monday.

Hamilton Mayor Andrea Horwath told reporters last week she’s called the city auditor to investigate the circumstances of the leak and provide a full public report upon completion.

"What I want to see, what we need to see as Hamiltonians, is some evidence as to how this occurred and was able to go undetected for this length of time," Horwath said.

The city’s drinking water was not affected, Hamilton Water confirmed, adding that the overall risk of public exposure was "very low."

In July 2018, the city discovered a 24-billion-litre sewage leak in Chedoke Creek. Remediation efforts remain ongoing in the Chedoke Creek area.