Data & Methodology — Tom Green County

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

Contaminant Data — All Analytes

407 well testing events on record, covering 22 analytes. Data spans 1949 to 2023.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. TX Avg
Radon 1 2017 100%
173% of limit ↑ 381% above
Nitrate 59 1983–2017 98%
260% of limit ↑ 1068% above
Chloride 35 1983–2017 100%
108% of limit ↑ 202% above
Sulfate 33 1983–2017 100%
56% of limit ↑ 96% above
Iron 141 1950–2019 34%
7% of limit ↓ 96% below
Manganese 144 1950–2019 29%
15% of limit ↓ 76% below
Lead 125 1983–2019 22%
16% of limit ~ typical
Fluoride 380 1950–2019 98%
18% of limit ↓ 27% below
Arsenic 143 1983–2019 69%
30% of limit ↓ 21% below
HFPO-DA (GenX) municipal 31 2023–2024 0%
— —
Nitrite 9 1983–2017 11%
9% of limit ↑ 774% above
PFHxS municipal 31 2023–2024 74%
71% of limit ↑ 61% above
PFNA municipal 31 2023–2024 0%
— —
PFOA municipal 31 2023–2024 0%
— —
PFOS municipal 31 2023–2024 0%
— —
Uranium 41 2007–2019 100%
12% of limit ↓ 25% below
PFBS municipal 31 2023–2024 81%
— ↑ 43% above
pH 33 1983–2017 100%
— ~ typical
Sodium 33 1983–2017 100%
— ~ typical
Total Coliform 1 2017 0%
— —
E. coli 1 2017 0%
— —
Hardness 33 1983–2017 100%
— ↑ 127% above

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 Tom Green County

Of the 143 arsenic tests on record for Tom Green County (1983–2019), 31% found none, and half were below 2.4 µg/L.

Of the 35 chloride tests on record for Tom Green County (1983–2017), 0% found none, and half were below 270 mg/L.

Of the 380 fluoride tests on record for Tom Green County (1950–2019), 2% found none, and half were below 700 µg/L.

Of the 141 iron tests on record for Tom Green County (1950–2019), 66% found none.

Of the 125 lead tests on record for Tom Green County (1983–2019), 78% found none.

Of the 144 manganese tests on record for Tom Green County (1950–2019), 71% found none.

Of the 59 nitrate tests on record for Tom Green County (1983–2017), 2% found none, and half were below 26 mg/L.

Of the 33 sulfate tests on record for Tom Green County (1983–2017), 0% found none, and half were below 140 mg/L.

Of the 41 uranium tests on record for Tom Green County (2007–2019), 0% found none, and half were below 3.5 µg/L.

Have a number from your lab? Enter it to see where it falls. Nothing is sent anywhere.

Want the full picture for your well? Check all your results.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Nitrate 59 samples
  • Chloride 35 samples
  • Sulfate 33 samples
  • Iron 141 samples
  • Manganese 144 samples
  • Lead 125 samples
  • Fluoride 380 samples
  • Arsenic 143 samples
  • Uranium 41 samples
  • pH 33 samples
  • Sodium 33 samples
  • Hardness 33 samples

Limited data (<15 samples) — interpret with caution

  • Radon 1 sample
  • Nitrite 9 samples
  • Total Coliform 1 sample
  • E. coli 1 sample

No private-well PFAS data for Tom Green County

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

23 Active public water systems
124,181 Residents on public water
14% Households on private wells

Public water systems in Tom Green 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 Tom Green 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 Tom Green County Prevalence TX Average Source Year
Nitrate Cancer prevalence 5.5% 6.1% 2020
Lead Heart disease rate 6.6% 7.4% 2020

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