Data & Methodology — Travis County

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

Contaminant Data — All Analytes

3280 well testing events on record, covering 22 analytes. Data spans 1967 to 2017.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. TX Avg
PFOS municipal 133 2023–2025 16%
138% of limit ~ typical
Iron 978 1938–2022 53%
20% of limit ↓ 87% below
Fluoride 2656 1937–2023 98%
8% of limit ↓ 69% below
PFOA municipal 133 2023–2025 4%
152% of limit ↑ 27% above
PFNA municipal 133 2023–2025 5%
244% of limit ↑ 95% above
Manganese 827 1938–2022 37%
6% of limit ↓ 91% below
Sulfate 1013 1978–2023 100%
12% of limit ↓ 59% below
Lead 682 1977–2022 26%
2% of limit ↓ 90% below
Chloride 1013 1978–2023 100%
8% of limit ↓ 78% below
Arsenic 744 1978–2022 52%
4% of limit ↓ 89% below
Nitrate 1170 1971–2023 94%
14% of limit ↓ 36% below
Nitrite 1004 1978–2023 16%
1% of limit ~ typical
HFPO-DA (GenX) municipal 133 2023–2025 0%
— —
PFHxS municipal 133 2023–2025 23%
48% of limit ~ typical
Radon 1 2017 100%
41% of limit ~ typical
Uranium 267 1980–2022 55%
3% of limit ↓ 81% below
E. coli 1 2008–2017 19%
— ~ typical
Hardness 1011 1978–2023 100%
— ↑ 35% above
PFBS municipal 132 2023–2025 23%
— ↑ 24% above
pH 1299 1978–2024 100%
— ~ typical
Sodium 1011 1978–2023 100%
— ↓ 90% below
Total Coliform 1 1978–2017 75%
— ~ 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 TX.

Compare your result with Travis County

Of the 744 arsenic tests on record for Travis County (1978–2022), 48% found none.

Of the 1013 chloride tests on record for Travis County (1978–2023), 0% found none, and half were below 19.5 mg/L.

Of the 2656 fluoride tests on record for Travis County (1937–2023), 2% found none, and half were below 300 µg/L.

Of the 978 iron tests on record for Travis County (1938–2022), 47% found none, and half were below 4.2 µg/L.

Of the 682 lead tests on record for Travis County (1977–2022), 74% found none.

Of the 827 manganese tests on record for Travis County (1938–2022), 63% found none.

Of the 1170 nitrate tests on record for Travis County (1971–2023), 6% found none, and half were below 1.4 mg/L.

Of the 1013 sulfate tests on record for Travis County (1978–2023), 0% found none, and half were below 28.9 mg/L.

Of the 267 uranium tests on record for Travis County (1980–2022), 45% found none, and half were below 0.43 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 978 samples
  • Fluoride 2656 samples
  • Manganese 827 samples
  • Sulfate 1013 samples
  • Lead 682 samples
  • Chloride 1013 samples
  • Arsenic 744 samples
  • Nitrate 1170 samples
  • Nitrite 1004 samples
  • Uranium 267 samples
  • Hardness 1011 samples
  • pH 1299 samples
  • Sodium 1011 samples

Limited data (<15 samples) — interpret with caution

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

No private-well PFAS data for Travis County

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

140 Active public water systems
1,555,359 Residents on public water
4% Households on private wells

Public water systems in Travis 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 Travis 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 Travis County Prevalence TX Average Source Year
Arsenic Cancer prevalence 5.4% 6.1% 2020
Arsenic Kidney disease rate 2.5% 3.3% 2020
Lead Heart disease rate 4.5% 7.4% 2020

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