Hillsborough County, New Hampshire: drinking water report. Hillsborough County encompasses New Hampshire's largest city, Manchester, along with Nashua,…
Hillsborough County encompasses New Hampshire's largest city, Manchester, along with Nashua, Merrimack, Hudson, and numerous smaller communities across southern New Hampshire. Water supplies draw primarily from the Merrimack River, which serves Manchester and several downstream municipalities, while Nashua relies on the Nashua River and Pennichook Brook reservoirs. Many smaller towns and rural areas depend on private wells drilled into fractured bedrock aquifers common throughout the region.
The Merrimack River faces legacy contamination from decades of industrial textile manufacturing, though treatment improvements have addressed many historical concerns. Manchester Water Works treats surface water through filtration and disinfection, while Nashua maintains dual reservoir systems with similar conventional treatment. Both utilities have conducted lead and copper monitoring under EPA requirements, with occasional exceedances in older neighborhoods where service lines installed before the 1950s remain in place. Like most New Hampshire communities, these systems add corrosion control chemicals to minimize lead leaching from household plumbing.
PFAS contamination represents the most pressing current concern across Hillsborough County. New Hampshire adopted some of the nation's strictest PFAS standards in 2019, setting maximum contaminant levels at 12 parts per trillion for PFOA and 15 ppt for PFOS. Multiple public water systems in the county have detected PFAS above these thresholds, primarily near former manufacturing sites and areas with historical use of firefighting foam. Merrimack in particular has faced elevated PFAS levels linked to past industrial operations. Several affected systems have installed granular activated carbon filtration or switched to alternative sources, though treatment infrastructure upgrades continue across the region.
Private well owners face distinct challenges. Bedrock wells in southern New Hampshire naturally contain elevated levels of uranium, radon, arsenic, and manganese in some areas due to the underlying geology. The New Hampshire Geological Survey maps show Hillsborough County sitting largely on granite formations that can release these contaminants as groundwater moves through fractures. Unlike public systems, private wells receive no routine monitoring unless owners arrange their own testing. State health officials recommend testing private wells at least once for PFAS, arsenic, uranium, and standard bacteria, though compliance remains voluntary.
Manchester and Nashua customers should request recent water quality reports from their utilities to understand current PFAS levels and lead monitoring results, particularly in homes built before 1960. Private well owners should test for the contaminants most common in southern New Hampshire bedrock aquifers rather than assuming well water is safe. Check your water for current data on your specific location, review our water filter guide for treatment options suited to different contaminants, request a detailed report for comprehensive testing history, or visit the New Hampshire state page for broader context on water quality patterns across the state.