Full contaminant data, sample history, and sourcing for Cape May County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
3103 well testing events on record, covering
22 analytes.
Data spans 1925 to 2025.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. NJ Avg
Manganese
344
1956–2023
83%
70% of limit
↓ 85% below
Iron
357
1952–2023
93%
29% of limit
↓ 94% below
Chloride
3051
1925–2023
100%
7% of limit
↓ 75% below
Nitrate
195
1926–2023
57%
5% of limit
↓ 81% below
Sulfate
375
1925–2023
99%
5% of limit
↓ 71% below
Fluoride
316
1952–2023
64%
5% of limit
~ typical
HFPO-DA (GenX)
municipal
79
2020–2025
0%
—
—
Lead
136
1984–2023
29%
7% of limit
↓ 72% below
Nitrite
153
1973–2023
27%
1% of limit
↓ 41% below
PFHxS
municipal
79
2020–2025
0%
—
—
PFNA
municipal
79
2020–2025
0%
—
—
PFOA
municipal
79
2020–2025
0%
—
—
PFOS
municipal
79
2020–2025
0%
—
—
Radon
10
1990–2023
100%
19% of limit
↓ 54% below
Uranium
13
1990–2018
62%
0% of limit
↓ 91% below
Arsenic
128
1984–2023
27%
2% of limit
↓ 88% below
E. coli
2
2006–2018
50%
—
~ typical
PFBS
municipal
79
2020–2025
1%
—
↓ 49% below
Total Coliform
2
2006–2018
75%
—
~ typical
Sodium
452
1952–2023
100%
—
↓ 29% below
Hardness
368
1925–2023
99%
—
↓ 67% below
pH
861
1952–2023
100%
—
~ typical
Distribution shows the share of samples in each concentration band relative to the EPA Maximum Contaminant Level (MCL): Low = below half the MCL, Moderate = between half and the MCL, High = above the MCL. Analytes without an MCL (e.g. sodium, pH) show — in the limit columns. State average is based on county median values across NJ.
Compare your result with Cape May County
Of the 128 arsenic tests on record for Cape May County (1984–2023),
73% found none.
Of the 3051 chloride tests on record for Cape May County (1925–2023),
0% found none, and half were below 18 mg/L.
Of the 316 fluoride tests on record for Cape May County (1952–2023),
36% found none, and half were below 100 µg/L.
Of the 357 iron tests on record for Cape May County (1952–2023),
7% found none, and half were below 69 µg/L.
Of the 136 lead tests on record for Cape May County (1984–2023),
71% found none.
Of the 344 manganese tests on record for Cape May County (1956–2023),
17% found none, and half were below 26.8 µg/L.
Of the 195 nitrate tests on record for Cape May County (1926–2023),
43% found none, and half were below 55 µg/L.
Of the 375 sulfate tests on record for Cape May County (1925–2023),
1% found none, and half were below 12 mg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Manganese 344 samples
Iron 357 samples
Chloride 3051 samples
Nitrate 195 samples
Sulfate 375 samples
Fluoride 316 samples
HFPO-DA (GenX) 79 samples
Lead 136 samples
Nitrite 153 samples
PFHxS 79 samples
PFNA 79 samples
PFOA 79 samples
PFOS 79 samples
Arsenic 128 samples
PFBS 79 samples
Sodium 452 samples
Hardness 368 samples
pH 861 samples
Limited data (<15 samples) — interpret with caution
Radon 10 samples
Uranium 13 samples
E. coli 2 samples
Total Coliform 2 samples
Public vs. Private Water in Cape May County
165Active public water systems
537,675Residents on public water
36%Households on private wells
Public water systems in Cape May County are regulated by the EPA and must test and report contaminant levels. Private well owners are responsible for their own testing — there is no routine monitoring of private wells by any government agency.
CDC Health Outcome Correlations
Where contaminants detected in Cape May County have established associations with specific health outcomes, we cross-reference CDC PLACES county-level prevalence data. This is a contextual signal, not a causal claim.
This report aggregates data from the following public databases:
Water Quality Portal (WQP) — groundwater sample results for Cape May County from EPA, USGS, and state agencies. Browse WQP data →
EPA Safe Drinking Water Information System (SDWIS) — public water system inventory used to estimate the share of residents on private wells. Browse SDWIS →
Census ACS 5-Year Estimates — well and cistern household counts (variable DP04_0074E) used to calculate the private-well percentage for Cape May County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Cape May County, which informs which contaminants are geologically likely. USGS Aquifer Atlas →
EPA UCMR 5 (2023–2025) — PFAS occurrence data from public water systems, used as a proxy indicator for aquifer PFAS exposure. Rows marked "municipal" in the table above come from this source. About UCMR 5 →
EPA Toxics Release Inventory (TRI) — industrial facility chemical releases near Cape May County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Cape May County, used in contamination risk scoring. Superfund site search →
CDC PLACES — county-level health outcome prevalence (kidney disease, cancer, heart disease) correlated with detected contaminants. About CDC PLACES →
Methodology
Raw records are downloaded from the Water Quality Portal and normalized to µg/L (ppb). Records are deduplicated by sample ID and date, and certified outliers are excluded. Analyte names are mapped to EPA canonical forms. Detection rates, distribution bands, and MCL comparisons are computed from the normalized dataset.
Distribution bands use the EPA Maximum Contaminant Level as the threshold: concentrations below 50% of the MCL are classed as Low, between 50% and 100% as Moderate, and above 100% as High. For analytes without an MCL (sodium, hardness, pH), distribution is not computed.
State comparison uses the median of county median values across all counties in NJ with at least one sample for that analyte.