Data & Methodology — Essex County

Full contaminant data, sample history, and sourcing for Essex County. For readers who want to go beyond the summary.

Contaminant Data — All Analytes

144 well testing events on record, covering 20 analytes. Data spans 1925 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. NJ Avg
Radon 1 1987 100%
467% of limit ↑ 1015% above
PFOA municipal 123 2022–2025 64%
170% of limit ~ typical
Chloride 59 1925–2022 100%
17% of limit ↓ 42% below
PFOS municipal 123 2022–2025 23%
120% of limit ↓ 29% below
Manganese 57 1959–2022 68%
3% of limit ↓ 99% below
Sulfate 59 1925–2022 100%
16% of limit ~ typical
Iron 58 1925–2022 60%
10% of limit ↓ 98% below
PFHxS municipal 123 2022–2025 18%
43% of limit ~ typical
PFNA municipal 123 2022–2025 2%
100% of limit ↑ 131% above
Arsenic 36 1987–2022 67%
10% of limit ↓ 41% below
Fluoride 51 1959–2022 86%
2% of limit ↓ 71% below
HFPO-DA (GenX) municipal 123 2022–2025 0%
— —
Lead 34 1986–2022 38%
2% of limit ↓ 91% below
Nitrate 59 1925–2022 95%
14% of limit ↓ 42% below
Nitrite 43 1987–2022 23%
0% of limit ↓ 70% below
Uranium 5 1986–2003 100%
3% of limit ↓ 27% below
Sodium 57 1959–2022 100%
— ↓ 54% below
pH 65 1959–2022 100%
— ~ typical
PFBS municipal 123 2022–2025 16%
— ~ typical
Hardness 59 1925–2022 100%
— ↑ 80% above

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 Essex County

Of the 36 arsenic tests on record for Essex County (1987–2022), 33% found none, and half were below 0.375 µg/L.

Of the 59 chloride tests on record for Essex County (1925–2022), 0% found none, and half were below 42.3 mg/L.

Of the 51 fluoride tests on record for Essex County (1959–2022), 14% found none, and half were below 50 µg/L.

Of the 58 iron tests on record for Essex County (1925–2022), 40% found none, and half were below 4.65 µg/L.

Of the 34 lead tests on record for Essex County (1986–2022), 62% found none.

Of the 57 manganese tests on record for Essex County (1959–2022), 32% found none.

Of the 59 nitrate tests on record for Essex County (1925–2022), 5% found none, and half were below 1.38 mg/L.

Of the 59 sulfate tests on record for Essex County (1925–2022), 0% found none, and half were below 40 mg/L.

Have a number from your lab? Enter it to see where it falls. Nothing is sent anywhere.

Want the full picture for your well? Check all your results.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • PFOA 123 samples
  • Chloride 59 samples
  • PFOS 123 samples
  • Manganese 57 samples
  • Sulfate 59 samples
  • Iron 58 samples
  • PFHxS 123 samples
  • PFNA 123 samples
  • Arsenic 36 samples
  • Fluoride 51 samples
  • HFPO-DA (GenX) 123 samples
  • Lead 34 samples
  • Nitrate 59 samples
  • Nitrite 43 samples
  • Sodium 57 samples
  • pH 65 samples
  • PFBS 123 samples
  • Hardness 59 samples

Limited data (<15 samples) — interpret with caution

  • Radon 1 sample
  • Uranium 5 samples

Public vs. Private Water in Essex County

24 Active public water systems
672,447 Residents on public water
1% Households on private wells

Public water systems in Essex 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 Essex 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.

Contaminant Associated Condition Essex County Prevalence NJ Average Source Year
Lead Heart disease rate 5.6% 5.8% 2020
PFOA Cancer prevalence 5.7% 6.2% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Essex County CDC PLACES data →

Data Sources

This report aggregates data from the following public databases:

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.

Last updated: 2026-08-04

Full methodology →