Oak Hills Water Hardness & Quality Report (2026)

Oak Hills, an unincorporated community in Washington County, Oregon, relies on regional water providers, likely the Tualatin Valley Water District or the City of Hillsboro. The Tualatin Valley Water district draws from multiple sources, including the Joint Water Commission and Portland Water Bureau supplies. Because there’s no dedicated Oak Hills water system, residents should reach out to TVWD or Hillsboro Water for details specific to their address. The Tualatin Valley Water district's primary source is the Bull Run watershed, which drains Mount Hood Cascade andesite and Columbia River Basalt.

The Bull Run watershed's geology is dominated by Quaternary Mount Hood Cascade andesite and Miocene Columbia River Basalt. Both of these volcanic rock types are largely insoluble. This geological makeup means the water drawn from this watershed is naturally very soft. The broader Willamette Valley region, where Oak Hills sits, features a mix of alluvial deposits over older volcanic and sedimentary rocks, contributing to generally soft to moderately mineralized water supplies across the area.

Because the water is very soft, you might notice less soap scum and fewer mineral deposits on fixtures. However, very soft water can sometimes taste a bit flat to some people. If you're concerned about potential mineral buildup in appliances like water heaters or dishwashers, a water softener might be something to consider, though it's often not strictly necessary with this type of supply. Residents should always check the official water quality reports from their specific provider, such as TVWD or Hillsboro Water, for the most accurate information on their water's composition.