Gloucester Water Hardness & Quality Report (2026)

Gloucester (now amalgamated into the City of Ottawa) is served by City of Ottawa Water Services, drawing from the Ottawa River via the Lemieux Island water treatment plant. However, the eastern Ottawa/Gloucester distribution zone has historically been supplemented with groundwater from the Ordovician limestone and dolostone aquifer underlying the Ottawa Valley east of the city. Treatment includes conventional coagulation, filtration, UV disinfection, and chloramination, meeting all Guidelines for Canadian Drinking Water Quality (GCDWQ) standards. Hardness in the Gloucester distribution zone is 204 mg/L (11.9 gpg) — classified as very hard by Health Canada, substantially higher than the Ottawa city-wide average due to the carbonate groundwater component.

The elevated hardness in Gloucester's supply reflects the Ottawa Valley geology east of the city, where Ordovician dolostone and limestone (including the Gull River and Hull formations) underlie the glacial till plain. Groundwater from these confined and semi-confined carbonate aquifers carries high concentrations of dissolved calcium bicarbonate — significantly harder than Ottawa River surface water alone. As this harder groundwater blends into the eastern Ottawa distribution network, it elevates measured hardness well above the Ottawa River baseline, producing the very hard water characteristic of the Gloucester zone.

At 204 mg/L, Gloucester households deal with persistent and heavy hard water problems — rapid scale deposits on kettle elements, showerheads, and inside hot water tanks are common. Descaling kettles every three to four weeks is typical. Electric hot water tank elements can accumulate significant scale within two years; annual inspection and flushing are strongly recommended. A whole-home water softener is advisable for Gloucester homes — the very hard groundwater-blended supply places significant long-term wear on appliances, pipes, and fixtures.