Well water in Princeton, New Jersey
In Princeton, 29% of 56 private wells tested between 2002 and 2024 had total coliform above the New Jersey limit (any detection), according to NJDEP.
56 private wells tested 2002 to 2024 in state summaries; 21 individual samples from 12 wells, 1988 to 2024. 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.
| Contaminant | Wells tested | Above state level | Median | 95th pct | Highest | State level | |
|---|---|---|---|---|---|---|---|
| Total coliform | 56 | 29% | |||||
| Iron | 56 | 16% | 300 ug/L | ||||
| Arsenic | 56 | 16% | 5 ug/L | ||||
| E. coli Fecal coliform or | 56 | 9% | |||||
| Manganese | 56 | 5% | 50 ug/L | ||||
| Gross alpha | 50 | 4% | 15 pCi/L | ||||
| Nitrate | 56 | 0% | 10 mg/L |
What individual samples found
Each row summarizes every public sample for that contaminant inside Princeton. 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 | |
|---|---|---|---|---|---|---|---|
| Arsenic 1988 to 2024 | 21 | 24% | 5% | 0 | 23 | 10 ug/L EPA limit | |
| Radium (226 + 228) 1989 to 1990 | 12 | 8% | 0% | 0 | 0 | 5 pCi/L EPA limit | |
| Radon 1989 to 1990 | 12 | 100% | no limit | 2,600 | 39,200 | 2,000 pCi/L health guideline |
Sampled fewer than 10 times, too few to summarize: PFOA (2), Uranium (2), PFOS (2), Sodium (1).
Get the free Princeton well report
One email with the numbers above, what they mean for a home in Princeton, exactly which tests to order, and what treatment fits the local profile. No spam, unsubscribe in one click.
What this means
Among homeowners in Princeton who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (29% of 56 wells), arsenic (16% of 56 wells), and E. coli (9% of 56 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 exceeds the state's advisory level in a sizable share of wells; this is mostly a taste, staining or diet issue rather than a toxicity one.
What to test for in Princeton
- Total coliform29% of 56 local wells tested were above the New Jersey limit (any detection).
- Iron16% of 56 local wells tested were above the New Jersey nuisance level.
- E. coli9% of 56 local wells tested were above the New Jersey limit (any detection).
- Manganese5% of 56 local wells tested were above the New Jersey nuisance level.
- Gross alpha4% of 50 local wells tested were above the New Jersey limit.
- RadonMedian local reading is 2,600 pCi/L.
- PFOAAbove the limit in 2 of 2 local samples; too few to quote a rate.
- NitrateRecommended for every private well, especially near farms or septic systems.
Contamination sources on record in Princeton
NJDEP records 154 regulated sites in Princeton, among 154 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.
- 123
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 1
- lined landfill or transfer facility
- 30
- 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
- Arsenic
- Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
- E. coli
- Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
- Manganese
- Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
- Radon
- Aeration (bubble-up or diffused) whole-house; Granular activated carbon whole-house (lower levels only)
Get your Princeton water tested at home
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation. Tell us what you need and we match you with a company that serves Princeton.
Common questions
Is there arsenic in well water in Princeton?
Arsenic was detected in 24% of 21 public well samples in Princeton, and 5% 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 Princeton?
The median radon level across 12 public samples in Princeton was 2,600 pCi/L, with a high of 39,200 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Princeton?
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: 52 samples in Princeton. 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 7 contaminants in Princeton, up to 56 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: 154 regulated sites located in Princeton. 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.