Drinking Water Quality and Supply

From source to sink

Where Cornwall water comes from

A plain-language tour of the lakes, rivers, or wells that feed Cornwall, the plants that clean the water, and how it reaches kitchen taps. Lab grades for hardness, lead, and pH live on the water quality page.

On the map

Where Cornwall water lives

Source waters and treatment plants pinned from published utility names. Open a pin below for the full OpenStreetMap view.

Map showing drinking-water locations for Cornwall

Map data © OpenStreetMap contributors. Pins are approximate for orientation, not legal survey points.

Deep dive for households

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

Water is cleaned at Cornwall Water Purification Plant before it enters city pipes. Class 3 plant at 861 Second Street West. Intake and zebra-mussel control facilities at the base of R.H. Saunders Dam. Chemically assisted coagulation/flocculation, filtration, UV, and chlorine disinfection.

After treatment, water moves through pumps, storage, and underground mains to reach streets and buildings. Includes Boundary Road Reservoir and Tollgate Road elevated storage feeding the Class 3 city distribution system.

One detail that makes Cornwall water feel local: Cornwall’s intake sits at a major St. Lawrence power dam, so intake protection zones and zebra-mussel control are built into plant operations. Lab grades for hardness, lead, and pH sit on the city water quality page; this overview is about the route the water travels.

Where it starts

Surface water

Rivers, lakes, or reservoirs, not underground wells as the main draw.

Research confidence: high

Named source waters

  • Saint Lawrence River

Treatment plants

These are the buildings that filter and disinfect water before it enters city pipes.

  • Cornwall Water Purification Plant

    Class 3 plant at 861 Second Street West. Intake and zebra-mussel control facilities at the base of R.H. Saunders Dam. Chemically assisted coagulation/flocculation, filtration, UV, and chlorine disinfection.

How it reaches your street

Includes Boundary Road Reservoir and Tollgate Road elevated storage feeding the Class 3 city distribution system.

Cited sources

Supply notes summarize published utility materials. They are not a substitute for the issuing authority's current notices or for a licensed tap test.

Cornwall water quality grades · All city rankings

Source · ECCC / municipal open data (seed). Last updated 2026-07-22. Refreshed on the site's automated schedule.