St. Andrew-Windfields Water Hardness & Quality Report (2026)

St. Andrew-Windfields (a prestigious North York neighbourhood centred near York Mills Road and Leslie Street — one of Toronto's most affluent communities, named partly for the historic Windfields Farm, the breeding estate of Northern Dancer, Canada's greatest Thoroughbred racehorse, now a mix of mid-century custom homes, executive residences, and the former Ontario Science Centre parkland along the Don Valley) receives its drinking water from the City of Toronto, drawing from Lake Ontario via the R.C. Harris Water Treatment Plant. 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 235.5 mg/L (13.8 gpg) — classified as very hard by Health Canada, with TDS of 596 mg/L, consistent with the North York supply corridor.

St. Andrew-Windfields receives R.C. Harris plant Lake Ontario supply through the North York distribution network — the same characteristically very hard Lake Ontario source (dissolved Silurian and Devonian carbonate from the Great Lakes basin) as all Toronto boroughs. The 235.5 mg/L is consistent with the adjacent Victoria Village (237 mg/L) and other mid-North York communities in the same R.C. Harris distribution zone.

At 235.5 mg/L, St. Andrew-Windfields homeowners face persistent scale challenges in this neighbourhood's luxury housing stock — kettle and showerhead descaling every one to two weeks is typical. Whole-home water softeners are common in the area's executive homes. The City of Toronto provides water quality information at toronto.ca/water. Health Canada lead service line precautionary guidance applies to the neighbourhood's mid-century custom homes and any pre-1955 properties in the established residential streets.