Cheshire County, New Hampshire: drinking water report. Cheshire County in southwestern New Hampshire has about 77,000 residents, with Keene as the county…
Cheshire County in southwestern New Hampshire has about 77,000 residents, with Keene as the county seat. Water comes from a mix of surface sources (Babbidge Reservoir for Keene) and groundwater wells in the smaller communities. The Ashuelot River valley's agricultural activity and the region's fractured bedrock create varied water quality conditions across the county.
New Hampshire's strict PFAS standards – among the tightest in the country – have triggered detections across Cheshire County. According to the NH DES's 2024 PFAS monitoring report, two public water systems in the county exceeded the state's 12 ppt PFOA standard, requiring treatment or alternative supply development. The Dillant-Hopkins Airport in Keene has documented AFFF use as a likely source.
Naturally occurring arsenic in the county's bedrock affects private well users. A 2024 USGS bedrock aquifer study found that 17% of wells in the metamorphic and granitic rock formations of Cheshire County exceeded the arsenic MCL of 10 ppb. The variation is extreme – wells 100 feet apart can show dramatically different arsenic levels.
Cheshire County's combination of strict state PFAS standards and naturally occurring arsenic in bedrock means both concerns warrant attention. If you are on a private well, testing for arsenic and PFAS together gives you the full picture.
Check your water for any available data. For arsenic and PFAS together, reverse osmosis handles both. Our water filter guide covers systems proven for New Hampshire well water. Get your detailed report for local data, and visit our New Hampshire page for statewide patterns.