Saint-Constant Water Hardness & Quality Report (2026)

Saint-Constant's drinking water is managed by Ville de Saint-Constant, a south shore Montérégie suburb approximately 25 km south of Montréal, drawing from the regional Montérégie water supply system — sourced from the St. Lawrence River and supplemented by local groundwater — via the municipal treatment plant. Water undergoes coagulation, sedimentation, filtration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) requirements. Hardness measures 125 mg/L (7.3 gpg) — classified as hard by Health Canada, notably harder than the typical south shore Longueuil–Boucherville corridor (73–77 mg/L), reflecting the local groundwater contribution in this more rural south shore supply zone.

Saint-Constant lies further from the St. Lawrence River than the urban south shore suburbs and may rely to a greater extent on local aquifer groundwater from the Ordovician limestone Lowlands bedrock of the Montérégie plain. Groundwater from these carbonate aquifers carries elevated dissolved calcium from direct limestone contact, producing the 125 mg/L hardness — significantly harder than the diluted St. Lawrence surface supply of the urban waterfront communities closer to the river.

At 125 mg/L, Saint-Constant residents experience regular scale deposits on kettle elements and in hot water tanks — descaling every six to eight weeks is advisable. Annual hot water tank inspection and flushing are recommended. Ville de Saint-Constant publishes annual water quality reports following Ministère de l'Environnement standards. The municipality's mixed rural and suburban character, with significant post-2000 residential development, means most new housing meets modern Health Canada plumbing standards, though lead precautionary guidance remains applicable to older properties in the historic village core.