Sullivan County, New Hampshire: drinking water report. Sullivan County sits in western New Hampshire along the Connecticut River, encompassing Claremont
Sullivan County sits in western New Hampshire along the Connecticut River, encompassing Claremont (the county's largest city), Newport, Charlestown, and smaller rural communities. Residents draw water from municipal systems tied to the Sugar River and Connecticut River watersheds, private wells drilled into crystalline bedrock aquifers, and community water associations serving lake communities around Sunapee and smaller ponds. The mixed supply situation means water quality varies considerably depending on whether you receive treated surface water or rely on untested groundwater.
New Hampshire's location in the industrial northeast creates specific contamination patterns that Sullivan County shares with the broader region. PFAS (per- and polyfluoroalkyl substances) have emerged as the dominant concern across the state, with legacy industrial facilities, military installations, and former firefighting training sites contributing to groundwater plumes. While Sullivan County lacks the high-profile contamination zones found near former Air Force bases in southern New Hampshire, the widespread use of PFAS-containing products and septic systems means many private wells face low-level exposure risks that remain unmonitored.
Municipal systems serving Clareport and Newport follow EPA testing protocols under the Safe Drinking Water Act, including recent UCMR5 sampling that screened for 29 PFAS compounds and lithium. New Hampshire adopted some of the nation's strictest PFAS standards in 2019, setting maximum contaminant levels for PFOA, PFOS, PFHxS, and PFNA that fall well below federal advisory levels. This aggressive regulatory posture means municipal suppliers must invest in treatment when contamination appears, but it also means residents receive more transparent reporting than in states with looser standards. Private well owners face a different reality. New Hampshire does not require routine testing of private wells after initial construction, leaving roughly 40 percent of Sullivan County residents who rely on wells responsible for their own monitoring.
Arsenic presents another persistent challenge in western New Hampshire. The bedrock geology that underlies Sullivan County naturally contains arsenic-bearing minerals, and well water can leach this carcinogen as it moves through fractures in the granite and schist. The state estimates that roughly one in five private wells exceeds the EPA's 10 parts per billion standard for arsenic. Lead exposure risk in Sullivan County correlates with housing age. Homes built before 1986 (when lead solder was banned) and especially those constructed before 1950 face elevated risk from lead service lines and internal plumbing. Municipal systems serving older city centers like Claremont must conduct regular lead and copper rule testing, but homes with private wells and pre-1986 plumbing face unmonitored risk.
Test your water regardless of source. Municipal customers should request recent test results from their supplier and consider independent testing for lead if you live in older housing stock. Well owners should test annually for bacteria and every three to five years for arsenic, PFAS, uranium, and radon, which dissolves readily from New Hampshire granite. Check your water for the most current contamination data in your area, review our water filter guide to match treatment technology to specific contaminants, request your detailed report for comprehensive testing results, and visit the New Hampshire state page for regulatory context and statewide contamination patterns.