Dauphin County, Pennsylvania: drinking water report. Dauphin County is home to Pennsylvania's capital, Harrisburg, and about 286,000 residents.
Dauphin County is home to Pennsylvania's capital, Harrisburg, and about 286,000 residents. The Susquehanna River provides the primary water source, with Capital Region Water and United Water Suez operating the main treatment and distribution systems. The Susquehanna is the largest river on the East Coast draining into the Chesapeake Bay, and by the time it reaches Harrisburg, it carries agricultural, industrial, and municipal inputs from a vast upstream watershed.
The Susquehanna watershed's agricultural intensity drives nutrient loading at the Harrisburg intake. According to the Susquehanna River Basin Commission's 2024 water quality report, total nitrogen concentrations at the Harrisburg gauge averaged 3.2 mg/L during the spring flush – reflecting fertilizer and manure runoff from upstream farmland. Treatment plants convert this raw water into safe drinking water, but disinfection byproducts from the treatment process are an inevitable consequence of high-nutrient source water.
The Harrisburg International Airport and the former Olmsted Air Force Base (now a commercial airport) used AFFF firefighting foam for decades. Pennsylvania DEP's 2024 PFAS sampling found PFOS at 12 ppt in groundwater monitoring wells south of the airport. The EPA's UCMR5 data also showed PFAS detections in the Capital Region Water system.
Harrisburg's river-sourced water is thoroughly treated, but the high-nutrient source water means disinfection byproducts – particularly trihalomethanes and haloacetic acids – are worth monitoring at the tap, especially during warm months when byproduct formation accelerates.
Check your water for current results at your address. A carbon block filter reduces disinfection byproducts, while reverse osmosis adds PFAS protection. Our water filter guide covers systems appropriate for treated surface water. Pull your detailed report for seasonal trends, and visit our Pennsylvania page for statewide data.
Drinking water is one exposure route. These federal datasets also cover Dauphin County, PA.
The EPA places Dauphin County, PA in Zone 1 - the EPA's highest-risk category, where the predicted average indoor radon level is above 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.
65% of homes in Dauphin County, PA were built before 1980, and 26% 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 Dauphin County, PA averages 9 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