Dorval Water Hardness & Quality Report (2026)

Dorval's drinking water is managed by Ville de Dorval, drawing from the St. Lawrence River via Lake Saint-Louis on the southwest edge of Montréal Island — Dorval is the West Island municipality adjacent to the Montréal-Trudeau International Airport (Pierre Elliott Trudeau Airport, YUL), processing St. Lawrence supply through the municipal treatment facility. Water undergoes coagulation, sedimentation, filtration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) requirements. Hardness measures 68 mg/L (4.0 gpg) — classified as moderately hard by Health Canada, consistent with the West Island St. Lawrence shoreline supply character.

Dorval's 68 mg/L is consistent with the Lake Saint-Louis southwest Montréal Island supply corridor — similar to Beaconsfield (73 mg/L) and Westmount (65 mg/L), all sharing the characteristic moderately soft central St. Lawrence supply zone that is softer than the Ottawa River–influenced north shore West Island communities (Kirkland 115.5 mg/L). The St. Lawrence River at Lake Saint-Louis carries water from the Great Lakes outflow at a moderately hard 65–75 mg/L range, reflecting the diluted Great Lakes carbonate content after passage through the extensive St. Lawrence corridor.

At 68 mg/L, Dorval residents experience minimal-to-light scale deposits — occasional kettle cleaning every two to three months is adequate. Hot water tanks operate reliably at this hardness. Ville de Dorval publishes annual water quality reports following Ministère de l'Environnement standards. Dorval's Lakeshore Road waterfront and the residential areas south of the airport feature a mix of well-established post-war homes where Health Canada lead precautionary guidance applies to pre-1975 plumbing infrastructure.