Tap water warning still in effect for some Montreal homes

Those who live at a handful of addresses on Viger, de la Gauchetière and St-Alexandre are still being advised not to use the water, but the warning has been lifted, for the most part.

Residents at handful of addresses on Viger, de la Gauchetière and St-Alexandre still cannot use water

About 60 firefighters, as well as police and paramedics, were called to a multi-storey building at 445 Viger Street just after 4 p.m. Thursday. (Radio-Canada)

The City of Montreal has lifted, for the most part, a warning against using tap water in part of downtown.

The warning originally affected people living in the area bounded by Bleury Street, St-Antoine Street, Beaver Hall Hill and René-Lévesque Boulevard.

Now, only those living at the following addresses are affected:

  • 443-445-447-449-451-453-455 Viger Street West.
  • 454-456-470 de la Gauchetière Street West.
  • 1030 St-Alexandre Street.

Those who live at those residences should only use tap water to flush the toilet until further notice, the city says.

Firefighters were called to 445 Viger around 4 p.m. Thursday and discovered a valve on the building's cooling system had failed, which sent a chemical into the internal plumbing system.

Magnus, the company that makes the chemical, confirmed Friday that it was Magcare 107, which is used to prevent corrosion in water cooling systems.

It is "designed with a fluorescent dye-tracer to help detect it quickly. This product may cause nausea and diarrhea if swallowed. It is recommended to drink plenty of water and contact a poison control centre or doctor if exposed by ingestion," the company statement read.

The system is set up so that the drinking water can go into the cooling system, but something called a check valve ensures that dirty water can't flow back into the drinking water.

It appears as though the check valve is what malfunctioned, and the chemical leaked into the drinking water.

It then spread to adjacent buildings through a shared pipe.

Seven people felt ill, and four were taken to hospital as a precaution.

'The water was green'

Guiseppe Varchetta was working at a restaurant on the ground floor of the building on Viger when he noticed something wasn't right.

"The water was green. You know, Hulk, the Marvel cartoon? Like that."

More than 180 residents in the building were only allowed back in their homes at 1 a.m. Four people living in the building were taken to hospital as a precaution, to be treated for nausea, diarrhea and anxiety issues.

"We have security at every door informing owners not to use the water until the city has completed their expertise and we're distributing bottles of water at the same time," said Francois Guité, property manager.

The Environment Ministry sent out a news release saying "necessary measures" were put in place to ensure the safety of the city's residents, but does not outline what those measures are.

A representative from Urgence-Environnement was dispatched to the scene Thursday.

The city says the leak didn't contaminate the water network.

Inspection and testing to come

Given that the leak happened in a private building, the city says it is the owner's responsibility to ensure the plumbing is repaired and working properly. The province's building inspection board, the Régie du bâtiment, will then carry out an inspection.

Once that's done, the building owner must conduct water quality tests and submit the results to the city officials, who will issue a notice letting residents know when it is safe to use and consume their tap water again.​


  • Firefighters initially stated they suspected the chemical involved in the leak was to control bacteria and prevent deposits from forming. On Friday, the makers of the substance confirmed it was Magcare 107, a corrosion inhibitor.
    May 11, 2018 4:27 PM ET

With files from Lauren McCallum