Mimico Water Hardness & Quality Report (2026)

Mimico (a waterfront community in south Etobicoke, Toronto, along Lake Ontario between the Humber River and Long Branch) receives its drinking water from the City of Toronto, drawing from Lake Ontario via the Lakeview Water Treatment Plant in Mississauga — the primary source for Toronto's western Etobicoke lakeshore communities. Water is treated using ozonation, biofiltration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) standards. Hardness in Mimico's distribution zone is 205.5 mg/L (12.0 gpg) — classified as very hard by Health Canada, reflecting the western Lake Ontario supply corridor's significant carbonate mineral load.

Mimico sits directly on the Lake Ontario lakeshore in south Etobicoke, receiving supply from the Lakeview plant drawing from the western lake basin. Lake Ontario's western basin receives water from Lakes Huron, Erie, and the Georgian Bay corridor, carrying dissolved Silurian and Devonian carbonate minerals. The 205.5 mg/L at Mimico is somewhat lower than the 237–238 mg/L measured in Etobicoke's inland zones (Islington-City Centre West), reflecting the lakeshore supply zone's closer proximity to the treatment plant intake and the slightly different mineral profile of the lake's open-water zone vs. the distribution network.

At 205.5 mg/L, Mimico residents experience persistent scale build-up on kettle elements and in hot water tanks — monthly descaling is typical. Annual hot water tank inspection and flushing are recommended. Mimico's waterfront redevelopment brings many new condominium residents to this traditionally very hard water zone; the City of Toronto provides guidance at toronto.ca/water for new residents managing the characteristically very hard Lake Ontario supply.