Côte-Saint-Luc Water Hardness & Quality Report (2026)

Côte-Saint-Luc, a community of around 30,000 on Montreal Island, receives its water supply through the City of Montreal's system. This mixed water source combines water from the St. Lawrence River with supplementary groundwater, all treated at Montreal's filtration plants before entering Côte-Saint-Luc's distribution network. The City of Montreal conducts rigorous testing, sampling the water 30 times monthly within the distribution system and performing annual lead and copper tests at 40 homes, adhering to provincial ministry requirements.

The region's geology features Precambrian bedrock covered by Quaternary glacial deposits. Water drawn from the St. Lawrence River flows through the St. Lawrence Lowlands' limestone and dolomite formations. This geological context contributes a moderate level of dissolved minerals to the water supply, resulting in a variable composition due to the blend of surface and groundwater.

While Montreal states its treated water meets all standards, past testing from 2015-2018 revealed lead levels exceeding the provincial guideline in dozens of samples, a finding the city contested. Homeowners in older residences, especially those with suspected lead service lines, are encouraged to join the annual voluntary testing program by contacting the water department. Such participation can help identify potential issues and ensure the water reaching your tap is as safe as possible.