Grants Pass Water Hardness & Quality Report (2026)

The City of Grants Pass Public Works Department operates the water utility, sourcing all supply from the Rogue River. Water is treated at the Grants Pass Water Treatment Plant through coagulation with chemicals to form floc, sedimentation in basins, and disinfection with chlorine maintaining a residual of approximately 1.2 ppm entering the distribution system. The utility serves the city of Grants Pass in Josephine County, southern Oregon, providing drinking water to residential, commercial, and industrial customers across approximately 18 square miles.

The Rogue River watershed drains from the Cascade Range through the Siskiyou Mountains, influencing the water's chemistry via interaction with local geology. Limestone deposits contribute calcium carbonate to the water, while volcanic soils add magnesium and trace minerals from ancient formations. This geological profile results in moderately mineralized soft water, with seasonal variations tied to snowmelt and rainfall patterns affecting mineral dissolution rates throughout the year.

As a soft to moderately soft supply, Grants Pass water causes minimal scale buildup in pipes and appliances. Water heaters and dishwashers may accumulate light deposits over time, but regular flushing of fixtures and vinegar cleaning suffice; a water softener is typically unnecessary unless individual homes experience noticeable spotting. Water quality shows good compliance, averaging pH 7.2 post-treatment; chlorine disinfection residuals average around 1.2 ppm with summer peaks up to 2.5–5.1 ppm noted. Chlorate appears as a disinfection byproduct, and 4 contaminants exceed stricter health thresholds, though the supply scores A for legal limit compliance.