Data & Methodology — Hillsborough County

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

Contaminant Data — All Analytes

9267 well testing events on record, covering 23 analytes. Data spans 1923 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. FL Avg
Radon 75 1995–2012 100%
20% of limit ↓ 31% below
PFOS municipal 55 2023–2025 49%
135% of limit ↓ 36% below
Iron 2677 1923–2025 96%
80% of limit ↓ 60% below
Sulfate 3364 1923–2025 99%
21% of limit ↓ 21% below
Chloride 8617 1923–2025 100%
10% of limit ↓ 79% below
PFOA municipal 55 2023–2025 20%
192% of limit ↑ 35% above
Arsenic 843 1969–2024 79%
10% of limit ↓ 23% below
Manganese 1676 1942–2025 95%
11% of limit ↓ 57% below
Lead 901 1969–2024 28%
1% of limit ↓ 58% below
PFHxS municipal 55 2023–2025 31%
40% of limit ↓ 22% below
Nitrate 1215 1930–2023 84%
0% of limit ↓ 94% below
Fluoride 1980 1953–2025 92%
7% of limit ~ typical
Nitrite 1205 1969–2024 50%
1% of limit ~ typical
PFNA municipal 55 2023–2025 0%
— —
HFPO-DA (GenX) municipal 55 2023–2025 0%
— —
Uranium 128 1979–2012 82%
1% of limit ~ typical
Sodium 3135 1953–2025 100%
— ↓ 86% below
pH 3217 1942–2025 100%
— ~ typical
Hardness 2949 1923–2012 100%
— ↓ 23% below
E. coli 46 2002–2025 100%
— ~ typical
Fecal Coliform 66 1923–2021 60%
— ~ typical
PFBS municipal 55 2023–2025 56%
— ~ typical
Total Coliform 112 1923–2025 79%
— ~ 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 Hillsborough County

Of the 843 arsenic tests on record for Hillsborough County (1969–2024), 21% found none, and half were below 1 µg/L.

Of the 8617 chloride tests on record for Hillsborough County (1923–2025), 0% found none, and half were below 26 mg/L.

Of the 1980 fluoride tests on record for Hillsborough County (1953–2025), 8% found none, and half were below 240 µg/L.

Of the 2677 iron tests on record for Hillsborough County (1923–2025), 4% found none, and half were below 210 µg/L.

Of the 901 lead tests on record for Hillsborough County (1969–2024), 72% found none.

Of the 1676 manganese tests on record for Hillsborough County (1942–2025), 5% found none, and half were below 4.82 µg/L.

Of the 1215 nitrate tests on record for Hillsborough County (1930–2023), 16% found none, and half were below 10 µg/L.

Of the 3364 sulfate tests on record for Hillsborough County (1923–2025), 1% found none, and half were below 51 mg/L.

Of the 128 uranium tests on record for Hillsborough County (1979–2012), 18% found none, and half were below 72.5 ng/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Radon 75 samples
  • Iron 2677 samples
  • Sulfate 3364 samples
  • Chloride 8617 samples
  • Arsenic 843 samples
  • Manganese 1676 samples
  • Lead 901 samples
  • Nitrate 1215 samples
  • Fluoride 1980 samples
  • Nitrite 1205 samples
  • Uranium 128 samples
  • Sodium 3135 samples
  • pH 3217 samples
  • Hardness 2949 samples
  • E. coli 46 samples
  • Fecal Coliform 66 samples
  • Total Coliform 112 samples

No private-well PFAS data for Hillsborough County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Hillsborough 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 Hillsborough County

722 Active public water systems
1,743,513 Residents on public water
9% Households on private wells

Public water systems in Hillsborough 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 Hillsborough 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 Hillsborough County Prevalence FL Average Source Year
Arsenic Cancer prevalence 5.9% 6.8% 2020
Arsenic Kidney disease rate 3.0% 3.4% 2020
Lead Heart disease rate 6.3% 7.7% 2020

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