Well water in New Jersey

In New Jersey, 15% of 140,846 private wells tested between 2002 and 2024 had total coliform above the New Jersey limit (any detection), according to NJDEP.

141,301 private wells tested 2002 to 2024 in state summaries; 4,094 individual samples from 2,227 wells, 1906 to 2026. Data refreshed September 9, 2026.

What homeowner tests found

NJDEP Private Well Testing Act summaries: private wells tested and reported to the state, 2002 to 2024. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA. County and state figures combine the town summaries, weighted by wells tested; medians are not combined.

Contaminant	Wells tested	Above state level	State level
Iron	141,291	29%	300 ug/L
Manganese	141,293	20%	50 ug/L
Total coliform	140,846	15%
Gross alpha	99,698	11%	15 pCi/L
PFOA	20,186	10%	14 ng/L
PFOS	20,186	6%	13 ng/L
Arsenic	89,202	6%	5 ug/L
Nitrate	141,301	3%	10 mg/L
E. coli Fecal coliform or	140,562	2%
Uranium	19,354	1%	30 ug/L
PFNA	20,186	<1%	13 ng/L

What individual samples found

Each row summarizes every public sample for that contaminant inside New Jersey. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Samples	Detected	Above limit	Median	Highest	Limit
PFOA 2020 to 2026	319	67%	54%	5.3	160	4 ng/L EPA limit
PFOS 2020 to 2026	316	53%	31%	1.2	65	4 ng/L EPA limit
Radium (226 + 228) 1985 to 2022	1,518	86%	7%	1	67.2	5 pCi/L EPA limit
Nitrate 1973 to 2023	95	69%	5%	0.32	23.7	10 mg/L EPA limit
Arsenic 1906 to 2026	4,094	48%	2%	0	200	10 ug/L EPA limit
Lead 1971 to 2023	94	35%	2%	0	32.2	15 ug/L EPA limit
Uranium 1985 to 2022	940	63%	2%	0.03	623	30 ug/L EPA limit
Fluoride 1945 to 2023	94	64%	0%	0.1	1.85	4 mg/L EPA limit
Copper 1977 to 2022	93	47%	0%	0	0.08	1.3 mg/L EPA limit
Radon 1985 to 2024	864	99%	no limit	390	90,000	2,000 pCi/L health guideline
Chloride 1927 to 2023	96	100%	no limit	14	4,200	250 mg/L nuisance level
Manganese 1957 to 2022	96	93%	no limit	40	3,800	300 ug/L health guideline
Sodium 1950 to 2022	96	99%	no limit	9.11	7,000	20 mg/L health guideline
Iron 1951 to 2022	93	90%	no limit	71.2	133,000	300 ug/L nuisance level

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What this means

Among homeowners in New Jersey who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (15% of 140,846 wells), PFOA (10% of 20,186 wells), and PFOS (6% of 20,186 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.

Iron and manganese exceed the state's advisory level in a sizable share of wells; these are mostly a taste, staining or diet issue rather than a toxicity one.

What to test for in New Jersey

Volatile organic compounds (VOCs)120 hazardous waste sites on record locally.
Metals panel120 hazardous waste sites on record locally.
Iron29% of 141,291 local wells tested were above the New Jersey nuisance level.
Manganese20% of 141,293 local wells tested were above the New Jersey nuisance level.
Total coliform15% of 140,846 local wells tested were above the New Jersey limit (any detection).
Gross alpha11% of 99,698 local wells tested were above the New Jersey limit.
Radium (226 + 228)7% of 1,518 local samples were above the limit.
Lead2% of 94 local samples were above the limit.
E. coli2% of 140,562 local wells tested were above the New Jersey limit (any detection).
PFNA<1% of 20,186 local wells tested were above the New Jersey limit.

Contamination sources on record in New Jersey

NJDEP records 120 hazardous waste sites in New Jersey, among 51,119 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

120: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
38,157: registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
409: lined landfills and transfer facilities
12,433: other remediation projects

Treatment that fits the local profile

Total coliform: Inspect and repair the well cap and casing, then shock chlorinate and retest; UV disinfection whole-house; Chlorination system
PFOA: Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
PFOS: Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
Arsenic: Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Gross alpha: Point-of-use reverse osmosis; Water softener (cation exchange) for radium; Anion exchange for uranium
Radium (226 + 228): Water softener (cation exchange); Point-of-use reverse osmosis

Common questions

Is there arsenic in well water in New Jersey?

Arsenic was detected in 48% of 4,094 public well samples in New Jersey, and 2% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How high is radon in well water in New Jersey?

The median radon level across 864 public samples in New Jersey was 390 pCi/L, with a high of 90,000 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in New Jersey?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Counties in New Jersey

Atlantic6% total coliform
Bergen44% pfoa
Burlington9% total coliform
Camden7% total coliform
Cape May11% pfoa
Cumberland13% nitrate
Essex11% arsenic
Gloucester11% total coliform
Hunterdon23% total coliform
Mercer20% total coliform
Middlesex47% pfoa
Monmouth11% total coliform
Morris20% total coliform
Ocean6% total coliform
Passaic31% pfoa
Salem11% total coliform
Somerset24% total coliform
Sussex26% total coliform
Union18% total coliform
Warren26% total coliform

1 counties have fewer than 30 public samples and are included in the New Jersey totals above rather than shown separately: Hudson.

Sources

USGS Water Quality Portal: 8,808 samples in New Jersey. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
NJDEP Private Well Testing Act summaries: summaries for 11 contaminants in New Jersey, up to 141,301 wells each. 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.
NJDEP regulated sites: 51,119 regulated sites located in New Jersey. Known Contaminated Sites, regulated underground storage tank facilities and solid waste landfills from the New Jersey Department of Environmental Protection (NJ-GeoWeb). Retrieved September 9, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.