Mississauga Water Hardness & Quality Report (2026)

The Region of Peel provides water to roughly 800,000 residents across Mississauga, Brampton, and Caledon. The primary source is Lake Ontario, treated at the Lakeview Water Treatment Plant and the R.C. Harris Water Treatment Plant intake. Some groundwater from rural wells supplements this supply. The utility employs advanced methods like chlorination, filtration, and fluoridation, distributing water through more than 8,000 kilometers of pipes.

The watershed itself is part of the Great Lakes Basin, with Lake Ontario fed by rivers flowing over Paleozoic limestone and dolomite formations dating back to the Ordovician and Silurian periods. These ancient, soluble carbonate rocks naturally dissolve, releasing minerals like calcium and magnesium into the water. Even the groundwater sourced from local limestone aquifers contributes to this mineral content, resulting in a characteristically hard water supply.

This hard water can lead to visible limescale buildup inside pipes, potentially reducing water flow and the lifespan of plumbing. Homeowners often notice reduced efficiency in water heaters, sometimes by as much as 20-30%, and spotty residue on dishes from dishwashers. Fixtures and appliances like kettles and coffee makers are also prone to staining and scale accumulation. Regular descaling with vinegar can help manage this, and many residents find a whole-house water softener significantly extends appliance life and improves the effectiveness of cleaning products.