Data & Methodology — Polk County

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

Contaminant Data — All Analytes

2617 well testing events on record, covering 22 analytes. Data spans 1941 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. FL Avg
PFOS municipal 101 2023–2025 24%
151% of limit ↓ 28% below
Iron 1792 1959–2025 96%
7% of limit ↓ 97% below
Nitrate 431 1959–2019 71%
4% of limit ~ typical
Sulfate 2169 1941–2025 98%
4% of limit ↓ 85% below
Manganese 1695 1972–2025 92%
4% of limit ↓ 83% below
PFOA municipal 101 2023–2025 8%
145% of limit ~ typical
Chloride 2281 1941–2025 100%
5% of limit ↓ 90% below
Fluoride 1743 1959–2025 99%
8% of limit ~ typical
HFPO-DA (GenX) municipal 101 2023–2025 0%
— —
Nitrite 363 1972–2024 39%
0% of limit ↓ 76% below
PFNA municipal 101 2023–2025 0%
— —
Radon 11 2002–2019 100%
21% of limit ↓ 27% below
Uranium 32 1974–2019 66%
1% of limit ~ typical
Lead 291 1972–2024 37%
1% of limit ↓ 58% below
PFHxS municipal 101 2023–2025 12%
36% of limit ↓ 31% below
Hardness 582 1941–2019 100%
— ↓ 49% below
Total Coliform 158 1987–2025 98%
— ~ typical
Sodium 2017 1955–2025 99%
— ↓ 88% below
pH 2086 1941–2025 100%
— ~ typical
E. coli 68 2002–2025 97%
— ~ typical
Fecal Coliform 90 1987–2021 97%
— ~ typical
PFBS municipal 100 2023–2025 11%
— ~ 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 Polk County

Of the 2281 chloride tests on record for Polk County (1941–2025), 0% found none, and half were below 12.5 mg/L.

Of the 1743 fluoride tests on record for Polk County (1959–2025), 1% found none, and half were below 310 µg/L.

Of the 1792 iron tests on record for Polk County (1959–2025), 4% found none, and half were below 16.6 µg/L.

Of the 291 lead tests on record for Polk County (1972–2024), 63% found none.

Of the 1695 manganese tests on record for Polk County (1972–2025), 8% found none, and half were below 1.81 µg/L.

Of the 431 nitrate tests on record for Polk County (1959–2019), 29% found none, and half were below 23 µg/L.

Of the 2169 sulfate tests on record for Polk County (1941–2025), 2% found none, and half were below 9.33 mg/L.

Of the 32 uranium tests on record for Polk County (1974–2019), 34% found none, and half were below 0.107 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 1792 samples
  • Nitrate 431 samples
  • Sulfate 2169 samples
  • Manganese 1695 samples
  • Chloride 2281 samples
  • Fluoride 1743 samples
  • Nitrite 363 samples
  • Uranium 32 samples
  • Lead 291 samples
  • Hardness 582 samples
  • Total Coliform 158 samples
  • Sodium 2017 samples
  • pH 2086 samples
  • E. coli 68 samples
  • Fecal Coliform 90 samples

Limited data (<15 samples) — interpret with caution

  • Radon 11 samples

No private-well PFAS data for Polk County

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

401 Active public water systems
672,540 Residents on public water
9% Households on private wells

Public water systems in Polk 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 Polk 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 Polk County Prevalence FL Average Source Year
Nitrate Cancer prevalence 7.4% 6.8% 2020

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