Data & Methodology — Orange County

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

Contaminant Data — All Analytes

3411 well testing events on record, covering 23 analytes. Data spans 1952 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. FL Avg
Iron 983 1956–2025 98%
23% of limit ↓ 88% below
Chloride 3308 1956–2025 100%
36% of limit ↓ 27% below
PFOS municipal 90 2023–2025 13%
196% of limit ~ typical
Sulfate 2425 1956–2025 98%
36% of limit ↑ 36% above
PFOA municipal 90 2023–2025 4%
125% of limit ~ typical
Manganese 376 1961–2025 96%
7% of limit ↓ 74% below
Arsenic 369 1978–2025 84%
5% of limit ↓ 62% below
Fluoride 2177 1956–2025 98%
5% of limit ↓ 30% below
Nitrite 179 1969–2015 68%
0% of limit ↓ 96% below
HFPO-DA (GenX) municipal 90 2023–2025 0%
— —
PFNA municipal 90 2023–2025 0%
— —
Radon 37 1999–2015 100%
9% of limit ↓ 68% below
Uranium 26 1999–2015 81%
1% of limit ↓ 43% below
Lead 368 1978–2025 78%
0% of limit ↓ 89% below
Nitrate 388 1956–2015 90%
0% of limit ↓ 86% below
PFHxS municipal 90 2023–2025 1%
40% of limit ↓ 22% below
Hardness 2163 1956–2023 100%
— ↑ 51% above
Total Coliform 26 1978–2025 97%
— ~ typical
E. coli 14 2015–2025 93%
— ~ typical
Fecal Coliform 12 1978–2021 100%
— ~ typical
PFBS municipal 90 2023–2025 10%
— ~ typical
Sodium 2423 1956–2025 100%
— ~ typical
pH 2423 1956–2025 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 Orange County

Of the 369 arsenic tests on record for Orange County (1978–2025), 16% found none, and half were below 0.5 µg/L.

Of the 3308 chloride tests on record for Orange County (1956–2025), 0% found none, and half were below 89 mg/L.

Of the 2177 fluoride tests on record for Orange County (1956–2025), 2% found none, and half were below 200 µg/L.

Of the 983 iron tests on record for Orange County (1956–2025), 2% found none, and half were below 68 µg/L.

Of the 368 lead tests on record for Orange County (1978–2025), 22% found none, and half were below 50 ng/L.

Of the 376 manganese tests on record for Orange County (1961–2025), 4% found none, and half were below 3.23 µg/L.

Of the 388 nitrate tests on record for Orange County (1956–2015), 10% found none, and half were below 20 µg/L.

Of the 2425 sulfate tests on record for Orange County (1956–2025), 2% found none, and half were below 87 mg/L.

Of the 26 uranium tests on record for Orange County (1999–2015), 19% found none, and half were below 45 ng/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 983 samples
  • Chloride 3308 samples
  • Sulfate 2425 samples
  • Manganese 376 samples
  • Arsenic 369 samples
  • Fluoride 2177 samples
  • Nitrite 179 samples
  • Radon 37 samples
  • Uranium 26 samples
  • Lead 368 samples
  • Nitrate 388 samples
  • Hardness 2163 samples
  • Total Coliform 26 samples
  • Sodium 2423 samples
  • pH 2423 samples

Limited data (<15 samples) — interpret with caution

  • E. coli 14 samples
  • Fecal Coliform 12 samples

No private-well PFAS data for Orange County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Orange County. PFAS has been detected in local public water systems (UCMR 5 data) — indicated by the "municipal" badge in the table above — but this does not directly indicate private well contamination. 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 Orange County

114 Active public water systems
1,628,779 Residents on public water
5% Households on private wells

Public water systems in Orange 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 Orange 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 Orange County Prevalence FL Average Source Year
Arsenic Cancer prevalence 5.3% 6.8% 2020
Arsenic Kidney disease rate 2.9% 3.4% 2020

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