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

406 well testing events on record, covering 20 analytes. Data spans 1963 to 2019.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. TX Avg
Manganese 83 1971–2021 86%
94% of limit ↑ 46% above
Iron 280 1941–2021 86%
67% of limit ↓ 57% below
Radon 6 2002–2014 100%
11% of limit ↓ 69% below
PFOS municipal 25 2023–2025 12%
155% of limit ~ typical
Chloride 40 1971–2014 100%
23% of limit ↓ 36% below
PFOA municipal 25 2023–2025 4%
118% of limit ~ typical
Arsenic 83 1991–2021 25%
20% of limit ↓ 48% below
Fluoride 251 1941–2021 92%
5% of limit ↓ 79% below
HFPO-DA (GenX) municipal 25 2023–2025 0%
— —
Lead 78 1991–2021 15%
8% of limit ↓ 50% below
Nitrate 60 1971–2014 87%
1% of limit ↓ 96% below
Nitrite 13 1994–2014 0%
— —
PFHxS municipal 25 2023–2025 12%
55% of limit ↑ 25% above
PFNA municipal 25 2023–2025 0%
— —
Sulfate 40 1971–2014 100%
2% of limit ↓ 94% below
Uranium 31 1994–2021 32%
10% of limit ↓ 35% below
Hardness 40 1971–2014 100%
— ↓ 53% below
PFBS municipal 25 2023–2025 12%
— ↑ 31% above
pH 40 1971–2014 100%
— ~ typical
Sodium 40 1971–2014 100%
— ↓ 48% 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 TX.

Compare your result with Polk County

Of the 83 arsenic tests on record for Polk County (1991–2021), 75% found none.

Of the 40 chloride tests on record for Polk County (1971–2014), 0% found none, and half were below 57 mg/L.

Of the 251 fluoride tests on record for Polk County (1941–2021), 8% found none, and half were below 200 µg/L.

Of the 280 iron tests on record for Polk County (1941–2021), 14% found none, and half were below 140 µg/L.

Of the 78 lead tests on record for Polk County (1991–2021), 85% found none.

Of the 83 manganese tests on record for Polk County (1971–2021), 14% found none, and half were below 35 µg/L.

Of the 60 nitrate tests on record for Polk County (1971–2014), 13% found none, and half were below 80 µg/L.

Of the 40 sulfate tests on record for Polk County (1971–2014), 0% found none, and half were below 4 mg/L.

Of the 31 uranium tests on record for Polk County (1994–2021), 68% found none.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 83 samples
  • Iron 280 samples
  • Chloride 40 samples
  • Arsenic 83 samples
  • Fluoride 251 samples
  • Lead 78 samples
  • Nitrate 60 samples
  • Sulfate 40 samples
  • Uranium 31 samples
  • Hardness 40 samples
  • pH 40 samples
  • Sodium 40 samples

Limited data (<15 samples) — interpret with caution

  • Radon 6 samples
  • Nitrite 13 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

66 Active public water systems
67,351 Residents on public water
18% 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 TX Average Source Year
Arsenic Cancer prevalence 5.9% 6.1% 2020
Arsenic Kidney disease rate 3.1% 3.3% 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 TX with at least one sample for that analyte.

Last updated: 2026-08-04

Full methodology →