Brossard Water Hardness & Quality Report (2026)

Brossard's drinking water is managed by Ville de Brossard (part of the Longueuil agglomeration on the Montérégie South Shore), drawing from the St. Lawrence River via the Brossard Water Treatment Plant on the south shore. Water undergoes coagulation, sedimentation, filtration, UV disinfection, and chloramination, fully meeting the Guidelines for Canadian Drinking Water Quality (GCDWQ). Hardness measures 99.5 mg/L (5.8 gpg) — classified as moderately hard by Health Canada, somewhat higher than many Montréal island boroughs, reflecting Brossard's intake position on the St. Lawrence south shore where the harder main channel water is less diluted by Shield tributary flows.

Brossard's south shore intake location on the St. Lawrence River draws water from the main channel at a point downstream of the island of Montréal, where the Rivière des Prairies Shield tributary inflows have largely merged into the main river flow and the proportional contribution of softer Shield water is reduced. The St. Lawrence Lowlands Ordovician limestone plain through which the river flows at this location contributes proportionally more dissolved calcium, elevating the 99.5 mg/L hardness above the Montréal island distribution zone average.

At 99.5 mg/L, Brossard residents notice moderate scale deposits in kettles and on tap aerators — descaling every six to eight weeks is typical. Hot water tanks benefit from annual inspection. Ville de Brossard provides annual water quality reports following Ministère de l'Environnement provincial requirements, with hardness monitoring at multiple points throughout the distribution network. Residents in Brossard's significant stock of older apartment buildings and housing along the Autoroute 10 corridor should follow Health Canada lead guidance for properties with pre-1970 plumbing.