Wilsonville Water Hardness & Quality Report (2026)

Wilsonville, Oregon, in Clackamas County on the Willamette River south of Portland — a thriving Clackamas County suburban city known for its technology business parks and access to the Willamette Valley wine country — receives its municipal water from the City of Wilsonville Water Treatment Plant, which draws directly from the Willamette River at a riverside intake in Clackamas County. Wilsonville operates its own state-of-the-art treatment facility on the Willamette, providing municipal supply independent of the Portland regional water system.

The extremely soft 14.5 mg/L hardness and remarkably low TDS of 22.4 mg/L make Wilsonville's water one of the softest municipal supplies in the entire United States — softer than even most Pacific Northwest communities and approaching the mineral content of distilled water. The Willamette River at the Clackamas County reach drains the Oregon Cascades (Quaternary basalt, andesite, and rhyolite volcanic terrains of the High Cascades), the Western Cascades (Eocene-Miocene volcanic and volcaniclastic rocks), and the Oregon Coast Range (Eocene Siletz River Volcanics and Tyee Formation marine sandstone) — all igneous and marine siliciclastic terrains with no calcareous minerals. Pacific Northwest precipitation on these volcanic landscapes picks up essentially no dissolved minerals, creating a supply with TDS values approaching those of distilled water.

At 14.5 mg/L, Wilsonville's water is so soft it requires special consideration. Scale is essentially nonexistent — annual cleaning of heating appliances is more than sufficient. However, extremely soft, low-TDS water is naturally mildly corrosive — the very low buffering capacity means water is more likely to leach metals from older plumbing. Residents in homes with older copper or galvanized pipes should run cold water briefly before consuming. The PFAS level of 1.1 ppt is outstanding — among the lowest in the United States dataset — reflecting Wilsonville's pristine Willamette River watershed supply and its modern water treatment plant's exceptional performance.