Merrimack County, New Hampshire: drinking water report. Merrimack County sits in central New Hampshire, anchored by the state capital Concord and including…
Merrimack County sits in central New Hampshire, anchored by the state capital Concord and including communities like Franklin, Penacook, Hopkinton, and Bow. The county draws water from the Merrimack River itself, along with numerous smaller tributaries, wells tapping into bedrock aquifers, and municipal systems serving roughly 150,000 residents across its mix of urban and rural areas. The region's water infrastructure ranges from Concord's relatively modern treatment facilities to smaller town systems serving just hundreds of households.
New Hampshire faces persistent challenges with both legacy industrial contamination and newer threats that show up clearly in Merrimack County. The Merrimack River corridor has documented contamination from decades of textile manufacturing, leather tanning, and paper production, though modern treatment has reduced many historical pollutants. More concerning for current residents are the PFAS (per- and polyfluoroalkyl substances) detections that have become a statewide issue, with former manufacturing sites, military installations, and airports serving as known sources. Pease Air Force Base in nearby Rockingham County has drawn attention to the broader regional problem, and testing in multiple New Hampshire communities has found PFAS levels above the EPA's 2024 health advisories of 4 parts per trillion for individual compounds.
Granite bedrock geology presents another ongoing concern across Merrimack County. Private wells and some smaller public systems drawing from bedrock aquifers can show elevated levels of naturally occurring contaminants including uranium, radon, and arsenic. The New Hampshire Department of Environmental Services estimates that roughly one in five private wells statewide exceeds the arsenic standard of 10 parts per billion, with central New Hampshire's geology making this a realistic risk for well-dependent households in towns like Webster, Canterbury, and Loudon. Lead service lines remain present in older sections of Concord and Franklin, though recent inventories and replacement programs have begun addressing this infrastructure gap.
Testing under EPA's Unregulated Contaminant Monitoring Rule has also detected lithium in some New Hampshire systems at levels worth monitoring, though not yet regulated. Agricultural runoff contributes nitrates in rural areas, particularly where septic systems cluster near shallow wells. The county's water quality picture reflects New Hampshire's broader tension between preserved rural character and the legacy of its industrial past, with modern contaminants like PFAS now layered onto older concerns.
Residents on private wells should test for arsenic, uranium, and radon at minimum, while those on municipal systems should request their utility's most recent Consumer Confidence Report and look specifically for PFAS testing results. Anyone in older neighborhoods built before 1986 should consider lead testing, especially in homes with young children. Check your water for testing data in your ZIP code, review our water filter guide for treatment options matched to specific contaminants, get a detailed report showing what regulators have found in your area, or visit the New Hampshire state page for broader context on water quality across the state.