Arsenic in New Jersey well water
In New Jersey, 6% of 89,202 private wells tested between 2002 and 2024 had arsenic above the New Jersey limit (5 ug/L), according to NJDEP.
Arsenic occurs naturally in New England bedrock and dissolves into well water. Long-term exposure raises the risk of bladder, lung and skin cancers, and is linked to heart disease and lower IQ in children. It has no taste or smell, so testing is the only way to know.
Check your arsenic number
Type the value from your lab report. It is compared to the New Jersey limit and the EPA limit, the same way the full interpretation does it.
Getting it fixed
Book a free in-home water test with a licensed local company, or see the treatment guide for what removes arsenic.
By county, from homeowner tests
Share of private wells above the state guidance level (5 ug/L) in tests homeowners sent to the state lab, 2002 to 2024.
| County | Wells tested | Above state level | Highest | |
|---|---|---|---|---|
| Mercer | 3,466 | 18% | ||
| Somerset | 7,432 | 16% | ||
| Hunterdon | 13,700 | 16% | ||
| Essex | 231 | 11% | ||
| Bergen | 3,556 | 10% | ||
| Middlesex | 1,214 | 4% | ||
| Sussex | 10,608 | 2% | ||
| Warren | 5,457 | 2% | ||
| Morris | 13,097 | 2% | ||
| Passaic | 5,838 | 1% | ||
| Cumberland | 3,499 | <1% | ||
| Monmouth | 2,136 | <1% | ||
| Burlington | 4,684 | <1% | ||
| Gloucester | 3,687 | <1% | ||
| Salem | 2,056 | <1% |
Towns with the highest share above the state level
- Frenchtown borough, Hunterdon County67% of 46 wells
- Kingwood township, Hunterdon County43% of 688 wells
- East Amwell township, Hunterdon County43% of 616 wells
- Montgomery township, Somerset County34% of 966 wells
- Branchburg township, Somerset County29% of 710 wells
- Franklin township, Somerset County28% of 1,201 wells
- Hopewell township, Mercer County26% of 2,106 wells
- Alexandria township, Hunterdon County24% of 863 wells
- Raritan township, Hunterdon County22% of 2,269 wells
- Delaware township, Hunterdon County22% of 700 wells
- Hillsborough township, Somerset County21% of 1,124 wells
- Readington township, Hunterdon County19% of 2,067 wells
- West Amwell township, Hunterdon County17% of 406 wells
- Princeton, Mercer County16% of 56 wells
- Mendham borough, Morris County16% of 38 wells
- Lawrence township, Mercer County14% of 311 wells
- South Brunswick township, Middlesex County14% of 96 wells
- Fairfield township, Essex County13% of 181 wells
- Paramus borough, Bergen County13% of 45 wells
- Upper Saddle River borough, Bergen County13% of 1,237 wells
- Harding township, Morris County12% of 522 wells
- Lambertville, Hunterdon County11% of 122 wells
- Sandyston township, Sussex County10% of 321 wells
- Edison township, Middlesex County10% of 102 wells
- Saddle River borough, Bergen County10% of 594 wells
By county, from individual samples
Public monitoring samples against the EPA limit (10 ug/L); counties with at least 30 samples.
| County | Samples | Detected | Above EPA limit | Median | Highest |
|---|---|---|---|---|---|
| Somerset | 66 | 82% | 12% | 2.5 | 23 ug/L |
| Hunterdon | 196 | 74% | 11% | 2 | 57 ug/L |
| Bergen | 77 | 62% | 5% | 0.23 | 19.7 ug/L |
| Gloucester | 542 | 53% | 4% | 0.07 | 200 ug/L |
| Mercer | 168 | 69% | 4% | 0.4 | 23 ug/L |
| Union | 37 | 89% | 3% | 0.68 | 25.2 ug/L |
| Camden | 322 | 51% | 2% | 0.05 | 112 ug/L |
| Sussex | 123 | 52% | 2% | 0.08 | 19.7 ug/L |
| Burlington | 314 | 51% | 2% | 0.03 | 64.3 ug/L |
| Morris | 520 | 41% | 1% | 0 | 17 ug/L |
| Cumberland | 289 | 41% | 1% | 0 | 24.1 ug/L |
| Middlesex | 179 | 53% | <1% | 0.07 | 31.4 ug/L |
| Atlantic | 268 | 25% | <1% | 0 | 13 ug/L |
| Ocean | 271 | 37% | <1% | 0 | 12 ug/L |
| Essex | 41 | 71% | 0% | 0.39 | 7 ug/L |
Sources
- NJDEP Private Well Testing Act summaries: Share of private wells exceeding each standard in tests required at sale or lease under the New Jersey Private Well Testing Act, September 2002 to December 2024, published by NJDEP. Tests are untreated water at the time of sale or lease, so every well is counted once per transaction. Municipalities with fewer than ten wells are suppressed. Standards are New Jersey's: arsenic 5 ug/L, PFOA 14 ng/L, PFOS 13 ng/L, PFNA 13 ng/L, manganese and iron secondary standards. Uranium and PFAS were added to the required panel in 2021 and 2020, so their well counts are smaller. Retrieved September 9, 2026.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. arsenic counts and shares are listed on each county and town page with their sources.