Notre-Dame-de-Grâce Water Hardness & Quality Report (2026)

Notre-Dame-de-Grâce (NDG — a historically anglophone west-central borough of Ville de Montréal) receives its drinking water through Ville de Montréal — Direction de l'eau potable, drawing from the St. Lawrence River via the Atwater and DesBaillets water treatment plants. Treatment includes ozonation, biofiltration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) standards. Hardness in NDG's distribution zone is 126 mg/L (7.4 gpg) — classified as hard by Health Canada, notably higher than central or north Montréal boroughs, reflecting the west-central supply corridor's draw from the harder St. Lawrence mainstream supply at the Atwater plant.

NDG's supply corridor draws from the Atwater and DesBaillets treatment plants — both of which intake directly from the St. Lawrence River mainstream at the south-island shoreline. At this west-central island location, the proportion of harder Ordovician limestone-influenced St. Lawrence mainstream water is elevated relative to the north-island Rivière des Prairies intake zones, where Precambrian Shield tributary dilution more strongly moderates hardness. The NDG distribution zone's 126 mg/L reflects this proportionally harder mainstream supply.

At 126 mg/L, NDG residents experience noticeably more scale deposits than north or east Montréal neighbours — kettle descaling every six to eight weeks is advisable, and showerheads benefit from periodic soaking. Hot water tanks should be flushed annually. NDG's iconic mixed housing stock — Deco duplexes, brownstones, and apartment buildings spanning from the 1900s to the 1960s — places this borough among those where Montréal's Direction de l'eau potable most actively promotes Health Canada lead precautionary guidance and lead service line replacement, given the high prevalence of original plumbing in the neighbourhood's older properties.