Washington County, Pennsylvania: drinking water report. Washington County in southwestern Pennsylvania has about 208,000 residents.
Washington County in southwestern Pennsylvania has about 208,000 residents. The county draws water from surface sources including Ten Mile Creek and the Monongahela River, with Pennsylvania American Water and several municipal authorities providing service. The county sits atop the Marcellus Shale formation, making it one of the most active natural gas drilling regions in the eastern United States. That drilling activity adds a modern contamination concern to the area's existing coal mining legacy.
Fracking operations in Washington County have generated community concerns about groundwater contamination. According to the Pennsylvania DEP's 2024 oil and gas compliance report, the county had over 1,800 active unconventional gas wells. While the DEP maintains that properly constructed wells do not contaminate aquifers, the department investigated 12 water supply complaints related to drilling activity in Washington County during 2024.
Coal mine drainage remains a concurrent issue. A 2024 DEP assessment documented 90 miles of impaired streams in the county from abandoned mine drainage. The EPA's UCMR5 data also showed PFAS detections in Washington County's public water systems, likely from multiple diffuse sources rather than a single military or industrial origin.
Washington County's dual legacy of coal mining and modern gas drilling means groundwater quality depends heavily on location. Private well owners near active drilling pads should establish a baseline water quality test before drilling begins and retest periodically.
Check your water for the latest data on your supply. For the range of contaminants possible in this area – from methane and VOCs to mine drainage metals – reverse osmosis provides the broadest household protection. Our water filter guide covers both mining and drilling-related contamination scenarios. Get your detailed report for trend data, and visit our Pennsylvania page for statewide patterns.
Drinking water is one exposure route. These federal datasets also cover Washington County, PA.
The EPA places Washington County, PA in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 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.
68% of homes in Washington County, PA were built before 1980, and 32% 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 Washington County, PA averages 8.6 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
9 public water systems serving Washington County, PA have EPA lead testing on record. The reported lead sample skews toward systems that already flagged a problem, so its exceedance rate is not directly comparable with other areas. 9 water systems serving Washington County, PA carry a health-based EPA Safe Drinking Water Act violation.
| Most-cited violation type | Systems affected |
|---|---|
| Total Trihalomethanes (TTHM) | 6 |
| Revised Total Coliform Rule | 3 |
| Ground Water Rule | 2 |
| Total Organic Carbon | 2 |
| Long Term 2 Enhanced Surface Water Treatment Rule | 2 |
Source: EPA Lead and Copper Rule 90th-percentile tap sampling and EPA SDWIS Safe Drinking Water Act enforcement records, aggregated from the public water systems serving this county. Figures are counts of water systems, not a test of any individual home or tap.