Verdun Water Hardness & Quality Report (2026)

Verdun (a south Montréal island borough on the St. Lawrence waterfront) receives its drinking water through Ville de Montréal — Direction de l'eau potable, primarily from the St. Lawrence River via the DesBaillets Water Treatment Plant located in the borough itself — Montréal's largest treatment facility, drawing directly from the St. Lawrence mainstream adjacent to Verdun. Treatment includes ozonation, biofiltration, UV disinfection, and chloramination, fully meeting the Guidelines for Canadian Drinking Water Quality (GCDWQ). Hardness in Verdun's distribution zone is 123 mg/L (7.2 gpg) — classified as hard by Health Canada, substantially higher than most other Montréal boroughs, reflecting Verdun's direct DesBaillets St. Lawrence mainstream supply with less Shield tributary dilution.

Verdun's direct proximity to the DesBaillets plant — which draws from the St. Lawrence mainstream where the harder Ordovician limestone-influenced river chemistry predominates — results in harder supply than north-island boroughs receiving more Rivière des Prairies Shield-softened water. At this south-shore stretch, the St. Lawrence carries a higher proportion of harder upper-river water not yet substantially diluted by soft Shield tributaries, producing the elevated 123 mg/L measured in Verdun's distribution zone.

At 123 mg/L, Verdun residents experience more noticeable scale deposits than most Montréal neighbourhoods — kettle descaling every six to eight weeks is advisable. Hot water tanks benefit from annual flushing. For residents of Verdun's extensive early 20th-century duplex and triplex housing stock — a defining architectural feature of this historic South Shore borough — Montréal's Direction de l'eau potable strongly recommends following Health Canada precautionary lead guidelines and participating in the city's lead service line identification and replacement programme.