Sherbrooke Water Hardness & Quality Report (2026)

Sherbrooke's drinking water is managed by Ville de Sherbrooke, drawing from the Rivière Magog and its impounded Lac des Nations reservoir in the heart of the city, supplemented by intake from the Rivière Saint-François for peak demand. Water is treated at the Sherbrooke Water Treatment Plant using coagulation, sedimentation, filtration, UV disinfection, and chloramination, fully meeting the Guidelines for Canadian Drinking Water Quality (GCDWQ). Hardness measures 55 mg/L (3.2 gpg) — classified as soft by Health Canada, reflecting the relatively low-mineral character of the Eastern Townships watershed geology.

Sherbrooke sits within the Appalachian Highlands of the Eastern Townships — a complex geological province of ancient Cambrian and Ordovician sedimentary and volcanic sequences (the Québec Appalachians) heavily folded and metamorphosed. While the Appalachians include some limestone and dolostone formations, the predominant bedrock in the Sherbrooke watershed consists of more resistant slate, phyllite, and metavolcanic rock that dissolves very slowly on contact with rainwater and snowmelt. The Rivière Magog drains this moderately resistant terrain, yielding a supply that is soft relative to St. Lawrence Lowlands cities.

With 55 mg/L of hardness, Sherbrooke residents experience minimal scale build-up on taps and kettle elements — occasional descaling three to four times a year is sufficient. Hot water tanks perform reliably without scale treatment and have an extended lifespan compared to harder-water Québec cities. For households in Sherbrooke's older housing stock, Ville de Sherbrooke and the Ministère de l'Environnement recommend testing water at the tap for lead in pre-1970 properties with original lead service pipes, consistent with Health Canada guidelines.