Where Longueuil water comes from

Longueuil drinking water starts as surface water (rivers, lakes, or reservoirs). The named source on the utility record is St. Lawrence River. That is the water that eventually reaches kitchen taps after treatment, not a separate bottled brand.

Longueuil uses more than one treatment plant (Usine Mario-Petrone (usine locale); Usine Louise-Gravel (usine régionale); Usine Le Royer). Utilities often run plants in parallel so different neighbourhoods can be served, or so one plant can cover for another during maintenance. Usine Mario-Petrone (usine locale): Agglomeration filtration plant; UV disinfection added 2015; renamed from usine locale in 2022. Usine Louise-Gravel (usine régionale): Agglomeration filtration plant; UV disinfection added 2015; renamed from usine régionale in 2022.

After treatment, water moves through pumps, storage, and underground mains to reach streets and buildings. Agglomeration of Longueuil treats St. Lawrence water at three plants, stores it in six major reservoirs, and distributes via agglomeration transmission mains (~86 km) plus local networks (~1,700 km agglomeration-wide; Longueuil city ~995 km). Serves Longueuil, Boucherville, Brossard, Saint-Bruno-de-Montarville, and Saint-Lambert.

One detail that makes Longueuil water feel local: Agglomeration production capacity (N-1) of the three filtration plants is stated at 410,000 m³/day for a served population of about 448,000. Lab grades for hardness, lead, and pH sit on the city water quality page; this overview is about the route the water travels.