Pierce County, Washington: drinking water report. Pierce County – Tacoma and its surrounding communities – serves about 920,000 residents.
Pierce County – Tacoma and its surrounding communities – serves about 920,000 residents. Tacoma Water draws from the Green River and a system of wells tapping glacial aquifers fed by rainfall and snowmelt from Mount Rainier. Smaller suburban systems operate independently, some purchasing wholesale from Tacoma and others running their own wells. The region's abundant rainfall keeps supply ample, but the geology beneath the county creates varied groundwater quality.
The Green River watershed is largely forested and provides clean source water for Tacoma's surface supply. Groundwater quality varies more. Joint Base Lewis-McChord (JBLM), one of the largest military installations on the West Coast, sits in the southern part of the county and is a confirmed PFAS source from AFFF firefighting foam use. The Washington Department of Ecology has documented PFAS contamination in monitoring wells near the base.
According to the Washington DOE's 2024 PFAS investigation, several community water systems in the JBLM vicinity reported PFAS above the state's action level of 10 ppt for individual compounds. UCMR5 data confirms detections in six public water systems countywide.
If your water comes from Tacoma's Green River supply, your baseline is strong. Communities near JBLM should pay closer attention to PFAS data.
Check your water to see monitoring results for your specific area. For PFAS, activated carbon or reverse osmosis filters work at the household level. Our water filter guide details which certifications matter. Pull your detailed report, and visit our Washington page for statewide context.
Drinking water is one exposure route. These federal datasets also cover Pierce County, WA.
The EPA places Pierce County, WA in Zone 3 - the EPA's lowest-risk category, with a predicted average indoor radon level below 2 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
43% of homes in Pierce County, WA were built before 1980, and 14% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Pierce County, WA averages 8.2 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide