McMinnville Water Hardness & Quality Report (2026)

McMinnville Water & Light (MW&L) serves the city of McMinnville in Yamhill County, Oregon, providing drinking water to approximately 25,000 residents across a 30-square-mile service area. The utility sources its supply from four municipal wells tapping the local groundwater aquifer in the Willamette Valley. Water is treated at the MW&L treatment facility before distribution; no surface water reservoirs or rivers are used as primary sources.

The supply originates within the upper Willamette Valley groundwater basin, influenced by the Yamhill River subbasin. Key geological features include Quaternary alluvial sediments and terrace gravels overlying Tertiary volcanic rocks of the Siletz River Formation. This non-carbonate geology imparts a soft character to the water: rainwater infiltration through minimally reactive volcanic and sedimentary soils contributes little dissolved calcium or magnesium, yielding naturally low-mineralized groundwater typical of Pacific Northwest aquifers.

Soft water minimizes scale buildup on fixtures and appliances, reducing maintenance needs for dishwashers, washing machines, and water heaters. Soap lathers easily without excess use, and spotting on glassware is rare. No water softener is typically recommended; occasional sediment filtration may benefit plumbing longevity, and energy efficiency in heating systems remains high. MW&L complies with EPA standards, with pH typically around 7.5; no lead or copper exceedances are noted in recent monitoring. PFAS levels are below detection limits, corrosion control is managed via orthophosphates, and treatment includes chlorination, fluoridation, and basic filtration.