Sussex County, New Jersey: drinking water report. Sussex County in New Jersey's northwest corner has about 144,000 residents spread across the Kittatinny…
Sussex County in New Jersey's northwest corner has about 144,000 residents spread across the Kittatinny Ridge and surrounding valleys. Most communities rely on groundwater from fractured bedrock aquifers, with some surface water from small reservoirs. The county's rural character means a higher proportion of private wells than most New Jersey counties – roughly 40% of households are on private supply.
Naturally occurring arsenic and uranium in the county's granite and gneiss bedrock create baseline groundwater contamination that has nothing to do with human activity. According to the NJDEP's 2024 private well testing program data, 14% of tested wells in Sussex County exceeded the arsenic MCL of 10 ppb, and 8% showed gross alpha radiation above the 15 pCi/L standard – both driven by the local geology.
The former Picatinny Arsenal in neighboring Morris County has groundwater contamination that may extend into Sussex County's southern border area. NJDEP's 2024 investigation also identified PFAS in two public water systems in the county at levels requiring monitoring under New Jersey's strict standards.
With 40% of Sussex County on private wells, individual testing is the only way to know what is in your water. The naturally occurring arsenic and radionuclides in bedrock wells cannot be predicted by location alone – neighboring wells can show very different results.
We recommend checking your water for any available data, and investing in a comprehensive well test if you have not done so recently. For arsenic and radionuclides, specific treatment media and reverse osmosis are the effective options. Our water filter guide details which systems handle naturally occurring contaminants. Get your detailed report for context, and visit our New Jersey page for statewide patterns.