Parc-Extension Water Hardness & Quality Report (2026)

Parc-Extension (a densely populated and highly multicultural neighbourhood in the Villeray–Saint-Michel–Parc-Extension borough of Ville de Montréal, centred on Van Horne and Jarry areas) 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 Parc-Extension's distribution zone is 98.5 mg/L (5.8 gpg) — classified as moderately hard by Health Canada, reflecting the moderately hard St. Lawrence supply in this central Montréal distribution corridor.

Parc-Extension's 98.5 mg/L is slightly harder than the typical central Montréal borough range (70–82 mg/L), likely reflecting its position in the distribution network where the supply corridor draws a proportionally higher fraction of the harder direct St. Lawrence mainstream water compared to softer Rivière des Prairies–influenced zones in the same borough. The moderately hard supply is consistent with the neighbourhood's northern Montréal location, receiving supply from the Atwater plant's harder St. Lawrence channel intake.

At 98.5 mg/L, Parc-Extension residents experience moderate scale deposits in kettles and on tap aerators — descaling every two months is adequate. Hot water tanks operate reliably at this hardness without dedicated treatment. Parc-Extension's significance as a primary immigrant reception neighbourhood in Montréal means Ville de Montréal provides multilingual water quality information under the Ministère de l'Environnement reporting framework, including lead precautionary guidance critical for residents of this area's dense older housing stock.