Mercier Water Hardness & Quality Report (2026)

Mercier's drinking water is managed by the Ville de Mercier, drawing from the Châteauguay River — Mercier is a town in the Jardins-de-Napierville regional county in the Montérégie region of Quebec, south of Montreal on the Châteauguay River, a suburban community growing rapidly as a commuter municipality for Montreal's south shore, home to the historic Kahnawà:ke Mohawk Territory nearby (the largest Mohawk First Nation community in Canada, located at the Mercier Bridge on the south shore of the St. Lawrence), and the Mercier Bridge industrial corridor that connects the south shore to the Island of Montreal via the Châteauguay-LaSalle route. Water undergoes coagulation, sedimentation, filtration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) requirements. Hardness measures 103 mg/L (6.0 gpg) — classified as moderately hard by Health Canada, consistent with the south Montérégie river supply character.

Mercier draws from the Châteauguay River — the Châteauguay River drains the southwest Quebec Appalachian foothills and the Adirondack Mountain transition near the US border, carrying dissolved minerals from the Ordovician and Cambrian carbonate rocks of the south Montérégie plains terrain. At 103 mg/L, Mercier is in the mid-Montérégie supply range (session reference: south shore 69.5–128 mg/L), consistent with the Beauharnois (96.5 mg/L from batch 32) and Pincourt (79.5 mg/L from batch 34) south shore sub-zones. Water quality reports are published under Ministère de l'Environnement oversight.

At 103 mg/L, Mercier homes experience moderate scale deposits — cleaning every two months is adequate. Health Canada lead precautionary guidance applies to pre-1975 properties in the historic Mercier Châteauguay River corridor residential area.