Data & Methodology — Union County

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

Contaminant Data — All Analytes

107 well testing events on record, covering 19 analytes. Data spans 1923 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. NJ Avg
PFOA municipal 60 2022–2024 52%
135% of limit ↓ 32% below
Manganese 56 1953–2022 84%
120% of limit ↓ 75% below
Iron 56 1952–2022 82%
32% of limit ↓ 93% below
PFOS municipal 60 2022–2024 15%
140% of limit ~ typical
Sulfate 59 1952–2022 98%
17% of limit ~ typical
Arsenic 33 1985–2022 88%
7% of limit ↓ 58% below
Fluoride 52 1953–2022 85%
2% of limit ↓ 52% below
Chloride 59 1952–2022 100%
13% of limit ↓ 56% below
HFPO-DA (GenX) municipal 60 2022–2024 0%
— —
Lead 34 1985–2022 32%
1% of limit ↓ 97% below
Nitrate 55 1952–2022 82%
26% of limit ~ typical
Nitrite 36 1985–2022 39%
0% of limit ↓ 76% below
PFHxS municipal 59 2022–2024 12%
36% of limit ~ typical
PFNA municipal 57 2022–2024 0%
— —
Uranium 5 1985–2002 100%
11% of limit ↑ 133% above
Hardness 59 1952–2022 100%
— ↑ 65% above
PFBS municipal 60 2022–2024 10%
— ↓ 26% below
pH 67 1952–2022 100%
— ~ typical
Sodium 58 1952–2022 100%
— ↓ 49% below

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 Union County

Of the 33 arsenic tests on record for Union County (1985–2022), 12% found none, and half were below 0.66 µg/L.

Of the 59 chloride tests on record for Union County (1952–2022), 0% found none, and half were below 32 mg/L.

Of the 52 fluoride tests on record for Union County (1953–2022), 15% found none, and half were below 90 µg/L.

Of the 56 iron tests on record for Union County (1952–2022), 18% found none, and half were below 50 µg/L.

Of the 34 lead tests on record for Union County (1985–2022), 68% found none.

Of the 56 manganese tests on record for Union County (1953–2022), 16% found none, and half were below 21.1 µg/L.

Of the 55 nitrate tests on record for Union County (1952–2022), 18% found none, and half were below 2.3 mg/L.

Of the 59 sulfate tests on record for Union County (1952–2022), 2% found none, and half were below 43 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • PFOA 60 samples
  • Manganese 56 samples
  • Iron 56 samples
  • PFOS 60 samples
  • Sulfate 59 samples
  • Arsenic 33 samples
  • Fluoride 52 samples
  • Chloride 59 samples
  • HFPO-DA (GenX) 60 samples
  • Lead 34 samples
  • Nitrate 55 samples
  • Nitrite 36 samples
  • PFHxS 59 samples
  • PFNA 57 samples
  • Hardness 59 samples
  • PFBS 60 samples
  • pH 67 samples
  • Sodium 58 samples

Limited data (<15 samples) — interpret with caution

  • Uranium 5 samples

Public vs. Private Water in Union County

7 Active public water systems
778,855 Residents on public water
0% Households on private wells

Public water systems in Union 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 Union 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 Union County Prevalence NJ Average Source Year
Arsenic Cancer prevalence 5.4% 6.2% 2020
Arsenic Kidney disease rate 2.9% 2.7% 2020
Lead Heart disease rate 5.8% 5.8% 2020

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