Magog Water Hardness & Quality Report (2026)

Magog's drinking water is managed by Ville de Magog, drawing from Lac Memphrémagog — a spectacular, 43-km-long cross-border lake shared between Quebec and Vermont, where the headwaters rise in the Vermont Appalachian highlands and flow north into Quebec to discharge through the Magog River into the St. Francis River. Magog sits at the north end of this iconic lake at the heart of the Eastern Townships/Cantons-de-l'Est wine and tourism region. Water undergoes coagulation, sedimentation, filtration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) requirements. Hardness measures 97 mg/L (5.7 gpg) — classified as moderately hard by Health Canada, consistent with the Appalachian watershed supply character of the Eastern Townships.

Lac Memphrémagog's watershed drains the Green Mountains and Eastern Township Appalachians — a mixed terrain of Cambrian and Ordovician metasedimentary rocks, Devonian granitic intrusions (the Sherbrooke granites), and Cambrian quartzite ridges of the Québec Appalachian fold belt. This mixed Appalachian geological terrain dissolves moderately — harder than the pure Laurentian Shield sources (11–75 mg/L) but softer than the St. Lawrence Lowlands carbonate supply zones (84–128 mg/L). The 97 mg/L is consistent with the Eastern Townships Appalachian watershed character.

At 97 mg/L, Magog homes, lakeside properties, and tourism businesses experience moderate scale deposits — cleaning every two months is adequate. Hot water tanks have a reliable operational lifespan. Water quality reports are published following Ministère de l'Environnement standards. Health Canada lead precautionary guidance applies to pre-1975 properties in the historic Magog townsite along the lakeshore.