Data & Methodology — Bandera County

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

Contaminant Data — All Analytes

326 well testing events on record, covering 16 analytes. Data spans 1971 to 2016.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. TX Avg
Sulfate 37 1990–2016 100%
133% of limit ↑ 365% above
Iron 232 1941–2020 76%
87% of limit ↓ 43% below
Radon 13 1990–2016 100%
8% of limit ↓ 77% below
Manganese 217 1941–2020 62%
12% of limit ↓ 82% below
Fluoride 313 1941–2020 96%
50% of limit ↑ 111% above
Nitrate 56 1990–2016 59%
2% of limit ↓ 90% below
Arsenic 203 1988–2020 5%
16% of limit ↓ 58% below
Chloride 37 1990–2016 100%
9% of limit ↓ 75% below
Lead 196 1988–2020 15%
16% of limit ~ typical
Nitrite 17 1990–2016 24%
2% of limit ↑ 75% above
Uranium 36 1996–2020 8%
4% of limit ↓ 74% below
Total Coliform 1 2016 100%
— ~ typical
Sodium 38 1990–2016 97%
— ↓ 81% below
pH 37 1990–2016 100%
— ~ typical
Hardness 38 1990–2016 100%
— ↑ 127% above
E. coli 1 2016 0%
— —

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 Bandera County

Of the 203 arsenic tests on record for Bandera County (1988–2020), 95% found none.

Of the 37 chloride tests on record for Bandera County (1990–2016), 0% found none, and half were below 22.3 mg/L.

Of the 313 fluoride tests on record for Bandera County (1941–2020), 4% found none, and half were below 2 mg/L.

Of the 232 iron tests on record for Bandera County (1941–2020), 24% found none, and half were below 137 µg/L.

Of the 196 lead tests on record for Bandera County (1988–2020), 85% found none.

Of the 217 manganese tests on record for Bandera County (1941–2020), 38% found none, and half were below 2.44 µg/L.

Of the 56 nitrate tests on record for Bandera County (1990–2016), 41% found none, and half were below 15 µg/L.

Of the 37 sulfate tests on record for Bandera County (1990–2016), 0% found none, and half were below 332 mg/L.

Of the 36 uranium tests on record for Bandera County (1996–2020), 92% found none.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Sulfate 37 samples
  • Iron 232 samples
  • Manganese 217 samples
  • Fluoride 313 samples
  • Nitrate 56 samples
  • Arsenic 203 samples
  • Chloride 37 samples
  • Lead 196 samples
  • Nitrite 17 samples
  • Uranium 36 samples
  • Sodium 38 samples
  • pH 37 samples
  • Hardness 38 samples

Limited data (<15 samples) — interpret with caution

  • Radon 13 samples
  • Total Coliform 1 sample
  • E. coli 1 sample

No private-well PFAS data for Bandera County

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

CDC Health Outcome Correlations

Where contaminants detected in Bandera 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 Bandera County Prevalence TX Average Source Year
Nitrate Cancer prevalence 5.8% 6.1% 2020

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