Well water in Frelinghuysen township, New Jersey
In Frelinghuysen township, 35% of 363 private wells tested between 2002 and 2024 had total coliform above the New Jersey limit (any detection), according to NJDEP.
365 private wells tested 2002 to 2024 in state summaries; 5 individual samples from 3 wells, 1988 to 2007. 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.
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What this means
Among homeowners in Frelinghuysen township who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (35% of 363 wells), E. coli (6% of 359 wells), and PFOS (2% of 61 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.
Manganese and iron 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 Frelinghuysen township
- Total coliform35% of 363 local wells tested were above the New Jersey limit (any detection).
- Manganese22% of 365 local wells tested were above the New Jersey nuisance level.
- Iron19% of 365 local wells tested were above the New Jersey nuisance level.
- E. coli6% of 359 local wells tested were above the New Jersey limit (any detection).
- Gross alpha4% of 137 local wells tested were above the New Jersey limit.
- PFOS2% of 61 local wells tested were above the New Jersey limit.
- Arsenic1% of 292 local wells tested were above the New Jersey limit.
- Nitrate<1% of 365 local wells tested were above the New Jersey limit.
Contamination sources on record in Frelinghuysen township
NJDEP records 16 regulated sites in Frelinghuysen township, among 16 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.
- 15
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 1
- other remediation project
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
- E. coli
- Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system
- Manganese
- Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
- Radon
- Aeration (bubble-up or diffused) whole-house; Granular activated carbon whole-house (lower levels only)
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Common questions
Is there arsenic in well water in Frelinghuysen township?
Arsenic was detected in 20% of 5 public well samples in Frelinghuysen township, and 0% 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 Frelinghuysen township?
The median radon level across 1 public samples in Frelinghuysen township was 2,840 pCi/L, with a high of 2,840 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Frelinghuysen township?
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.
Sources
- USGS Water Quality Portal: 10 samples in Frelinghuysen township. 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 Frelinghuysen township, up to 365 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: 16 regulated sites located in Frelinghuysen township. 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.