Duncan Water Hardness & Quality Report (2026)

The City of Duncan Public Works manages the drinking water for the City of Duncan and parts of North Cowichan in British Columbia's Cowichan Valley Regional District. Their entire supply comes from the Lower Cowichan River Aquifer Complex, accessed through municipal wells. Water undergoes treatment at the Duncan Water Treatment Plant, where it's filtered, disinfected with chlorine, and stabilized before reaching about 5,000 residents. The Cowichan River watershed itself covers a vast 1,300 km² on southeastern Vancouver Island.

The groundwater originates in the unconfined Lower Cowichan River Aquifer Complex. This aquifer is made up of Quaternary-age glacial till, outwash sands, gravels, and silts that sit atop Tertiary bedrock, including the Carmanah Group sandstones. Because the water spends little time in contact with rocks rich in minerals like calcium and magnesium, and the sediments themselves contain few of these elements, the water comes out soft. This geology is typical for coastal aquifer systems in the region.

Homeowners in Duncan will likely notice the benefits of this soft water. You'll find less scale buildup in your pipes, water heaters, and faucets, which means less maintenance and better efficiency for your appliances. Soap and detergents will perform better, leaving fewer residues on dishes, clothes, and skin. Because the water isn't hard, a water softener isn't necessary; instead, it's wise to keep up with routine filter changes and monitor for corrosion, as low-mineral water can sometimes be more corrosive. Recent reports show the water meets all health guidelines, with stable pH and no issues with lead or copper at the tap.