Some samples taken show unsafe amounts of lead, though, exceeding Quebec’s 0.01 mg/L limit. The city suspects that the lead is being leached from its lead fresh water pipes. The province has implemented a program to eliminate all such lead pipes by 2025.
Some homes built prior to 1970 also have connecting pipes from the municipal waterworks system that are made of lead. If water remains stagnant in these pipes, lead could dissolve into the drinking water. This does not necessarily mean the lead content will exceed the provincial norm. Until 2001, the norm was 0.05 mg/L. Quebec cut that figure by 80 per cent upon the recommendation of Health Canada.
Since March 2013, cities that operate water treatment plants are required to file a written report whenever water quality falls below safety norms and explain why.
Six drinking-water plants remain on the Island of Montreal since the Sainte Anne de Bellevue plant closed in 2011.
They can treat up to 2,942,000 cubic meters per day, treat water from the St. Lawrence River, Lac St. Louis and Rivière des Prairies—the equivalent of 800 Olympic swimming pools—and distribute it through some 50 drinking-water networks.
The city also noted that all wastewater from houses, factories, retail buildings and almost all of the rainwater that falls on the island is recovered, purified and returned to the St. Lawrence River.
The May 22 boil-water advisory last year, the largest the city ever experienced, was the most important issue with regards to drinking water in the Montreal water service report. It affected some 1.3 million island residents.
The city said that citizens can get information or report a drinking water problem by dialing 311.