Sainte-Catherine Water Hardness & Quality Report (2026)

Sainte-Catherine's drinking water is managed by Ville de Sainte-Catherine, drawing from the St. Lawrence River or a local Montérégie south shore source — Sainte-Catherine is a south shore Montreal suburban municipality directly south of Montreal's Verdun district at the Mercier Bridge crossing, at the confluence of the St. Lawrence and the Rivière Châteauguay — a historically industrial community now transitioning to a residential suburb, home to many of Montreal's south shore commuter families. Water undergoes coagulation, sedimentation, filtration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) requirements. Hardness measures 128 mg/L (7.5 gpg) — classified as hard by Health Canada, at the harder end of the Montérégie south shore supply corridor.

Sainte-Catherine's 128 mg/L reflects the St. Lawrence Lowlands geology at the Montreal south shore — the Ordovician limestone and dolostone of the St. Lawrence Platform, partially covered by Champlain Sea marine clay deposits, releasing moderate dissolved calcium and bicarbonate into the local watershed. The Châteauguay River confluence zone produces harder water than the west DesBaillets Montreal supply (65–73 mg/L) but is softer than the eastern Montérégie zones. This is consistent with the south shore Montérégie supply range (84–125 mg/L) noted in the regional reference data.

At 128 mg/L, Sainte-Catherine homes experience regular scale deposits — monthly to bimonthly kettle cleaning is typical. Hot water tanks benefit from periodic inspection and flushing. Water quality reports are published following Ministère de l'Environnement standards. Health Canada lead precautionary guidance applies to pre-1975 residential properties in the municipality's older established neighbourhoods.