Mount Olive-Silverstone-Jamestown Water Hardness & Quality Report (2026)

Mount Olive-Silverstone-Jamestown (a northwest Toronto community in the Etobicoke district, bounded by Finch Avenue, Highway 427, and the Humber River valley — one of Toronto's more diverse and densely settled post-war residential districts) receives its drinking water from the City of Toronto, drawing from Lake Ontario via the Lakeview Water Treatment Plant in Mississauga. Water is treated using ozonation, biofiltration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) standards. Hardness in this distribution zone is 235 mg/L (13.7 gpg) — classified as very hard by Health Canada, with TDS of 593 mg/L, identical to adjacent West Humber-Clairville in the same northwest Etobicoke corridor.

Mount Olive-Silverstone-Jamestown shares the northwest Etobicoke distribution network supplied by the Lakeview plant's western Lake Ontario intake — producing the uniform very hard 235 mg/L that characterises all northwest Toronto supply zones. The dissolved Silurian and Devonian carbonate mineral load in Lake Ontario's western basin is consistent regardless of precise intake location or distribution routing, resulting in essentially the same hardness throughout the western Etobicoke residential districts.

At 235 mg/L, residents in Mount Olive-Silverstone-Jamestown face persistent scale challenges in a community that includes some of Toronto's largest high-rise social housing complexes. Kettle and showerhead descaling every one to two weeks is typical. The City of Toronto's lead service line replacement programme is particularly relevant for this area's older buildings; residents in the community's heritage social housing towers and mid-century apartment buildings are encouraged to review lead service line status at toronto.ca/water.