Data & Methodology — Knox County

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

Contaminant Data — All Analytes

859 well testing events on record, covering 13 analytes. Data spans 1966 to 2017.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. TX Avg
Nitrate 88 1974–1992 98%
160% of limit ↑ 617% above
Sulfate 119 1979–1992 100%
224% of limit ↑ 685% above
Chloride 119 1979–1992 100%
124% of limit ↑ 247% above
Iron 202 1944–2015 52%
27% of limit ↓ 83% below
Arsenic 114 1988–2015 54%
30% of limit ↓ 21% below
Manganese 194 1946–2015 16%
60% of limit ~ typical
Fluoride 780 1944–2015 99%
35% of limit ↑ 46% above
Lead 98 1988–2015 1%
33% of limit ↑ 98% above
Nitrite 37 1991–1992 51%
3% of limit ↑ 191% above
Uranium 16 2006–2015 100%
30% of limit ↑ 92% above
Sodium 54 1979–1992 100%
— ↑ 159% above
pH 68 1979–1992 100%
— ~ typical
Hardness 54 1979–1992 100%
— ↑ 268% 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 Knox County

Of the 114 arsenic tests on record for Knox County (1988–2015), 46% found none, and half were below 1 µg/L.

Of the 119 chloride tests on record for Knox County (1979–1992), 0% found none, and half were below 310 mg/L.

Of the 780 fluoride tests on record for Knox County (1944–2015), 1% found none, and half were below 1.4 mg/L.

Of the 202 iron tests on record for Knox County (1944–2015), 48% found none, and half were below 10 µg/L.

Of the 98 lead tests on record for Knox County (1988–2015), 99% found none.

Of the 194 manganese tests on record for Knox County (1946–2015), 84% found none.

Of the 88 nitrate tests on record for Knox County (1974–1992), 2% found none, and half were below 15.8 mg/L.

Of the 119 sulfate tests on record for Knox County (1979–1992), 0% found none, and half were below 560 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Nitrate 88 samples
  • Sulfate 119 samples
  • Chloride 119 samples
  • Iron 202 samples
  • Arsenic 114 samples
  • Manganese 194 samples
  • Fluoride 780 samples
  • Lead 98 samples
  • Nitrite 37 samples
  • Uranium 16 samples
  • Sodium 54 samples
  • pH 68 samples
  • Hardness 54 samples

No private-well PFAS data for Knox County

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

Public vs. Private Water in Knox County

8 Active public water systems
3,810 Residents on public water
10% Households on private wells

Public water systems in Knox 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 Knox 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 Knox County Prevalence TX Average Source Year
Arsenic Cancer prevalence 5.6% 6.1% 2020
Arsenic Kidney disease rate 3.1% 3.3% 2020

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