Portland Water Hardness & Quality Report (2026)

The Portland Water Bureau (PWB) serves approximately 950,000 residents across Portland and 26 surrounding municipalities in Multnomah, Washington, and Clackamas counties, Oregon. The primary source is the Bull Run Watershed reservoirs in the Mount Hood National Forest, with supplemental groundwater from the Columbia South Shore Well Field. Surface water receives only disinfection via chloramine and pH adjustment with no filtration requirement; groundwater undergoes similar basic treatment. Service covers approximately 146 square miles in the metro area.

The Bull Run Watershed spans 102 square miles of old-growth forest, draining protected reservoirs in continuous use since 1892 as an unfiltered supply under EPA exemption. Underlying geology consists of resistant Tertiary volcanic rocks — andesitic and basaltic volcanics — and granitic intrusions from the Western Cascades, which yield very soft water due to low solubility of silica-rich formations lacking limestone or dolomite. The Columbia South Shore Well Field taps shallower Quaternary alluvial deposits along the Columbia River, introducing moderately mineralized groundwater that slightly tempers the surface water's chemistry when blended seasonally, but overall mineralization remains consistently low.

Soft water at 9 mg/L means Portland avoids scale buildup entirely — water heaters, dishwashers, coffee makers, and laundry appliances benefit with no limescale reducing efficiency. Soap lathers abundantly, reducing detergent use significantly, and skin feels smoother without mineral residue. No water softener is needed and would be counterproductive for Portland's naturally pristine supply. Water pH ranges 8.0–9.0 for corrosion control, maintained via sodium hydroxide; the 2025 reports show no PFAS detections above limits, with trace arsenic, chromium-6, and TTHMs noted below MCLs. Treatment is minimal: chloramine disinfection, no filtration or fluoridation.