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

52 well testing events on record, covering 17 analytes. Data spans 1956 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. FL Avg
Iron 49 1980–2025 98%
99% of limit ↓ 51% below
Lead 49 1980–2025 98%
1% of limit ↓ 58% below
Arsenic 49 1980–2025 98%
8% of limit ↓ 40% below
Chloride 49 1980–2025 100%
3% of limit ↓ 94% below
Nitrite 3 1980–2015 67%
1% of limit ↓ 48% below
Fluoride 50 1980–2025 100%
4% of limit ↓ 39% below
Nitrate 3 1980–2015 67%
6% of limit ↑ 71% above
Sulfate 48 1980–2025 100%
2% of limit ↓ 92% below
Manganese 49 1980–2025 100%
18% of limit ↓ 33% below
Radon 1 2015 100%
29% of limit ~ typical
Uranium 2 2002–2015 50%
2% of limit ↑ 62% above
Hardness 3 1980–2015 100%
— ↓ 28% below
Total Coliform 12 2015–2025 92%
— ~ typical
Sodium 49 1980–2025 100%
— ↓ 90% below
pH 51 1972–2025 100%
— ~ typical
E. coli 6 2015–2025 86%
— ~ typical
Fecal Coliform 6 2017–2021 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 FL.

Compare your result with Union County

Of the 49 arsenic tests on record for Union County (1980–2025), 2% found none, and half were below 0.779 µg/L.

Of the 49 chloride tests on record for Union County (1980–2025), 0% found none, and half were below 7.5 mg/L.

Of the 50 fluoride tests on record for Union County (1980–2025), 0% found none, and half were below 174 µg/L.

Of the 49 iron tests on record for Union County (1980–2025), 2% found none, and half were below 290 µg/L.

Of the 49 lead tests on record for Union County (1980–2025), 2% found none, and half were below 0.2 µg/L.

Of the 49 manganese tests on record for Union County (1980–2025), 0% found none, and half were below 8.9 µg/L.

Of the 48 sulfate tests on record for Union County (1980–2025), 0% found none, and half were below 5.23 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 49 samples
  • Lead 49 samples
  • Arsenic 49 samples
  • Chloride 49 samples
  • Fluoride 50 samples
  • Sulfate 48 samples
  • Manganese 49 samples
  • Sodium 49 samples
  • pH 51 samples

Limited data (<15 samples) — interpret with caution

  • Nitrite 3 samples
  • Nitrate 3 samples
  • Radon 1 sample
  • Uranium 2 samples
  • Hardness 3 samples
  • Total Coliform 12 samples
  • E. coli 6 samples
  • Fecal Coliform 6 samples

No private-well PFAS data for Union County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Union County. PFAS testing for private wells requires a dedicated lab panel (~$300–$500). If you are near a military base, airport, or industrial site, consider testing proactively. Learn more about PFAS →

Public vs. Private Water in Union County

12 Active public water systems
5,387 Residents on public water
87% 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 FL Average Source Year
Arsenic Cancer prevalence 5.8% 6.8% 2020
Arsenic Kidney disease rate 3.3% 3.4% 2020
Lead Heart disease rate 8.7% 7.7% 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 FL with at least one sample for that analyte.

Last updated: 2026-08-12

Full methodology →