Full contaminant data, sample history, and sourcing for Wilson County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
482 well testing events on record, covering
20 analytes.
Data spans 1975 to 2023.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. TX Avg
Iron
309
1938–2020
88%
180% of limit
~ typical
Manganese
260
1938–2020
72%
97% of limit
↑ 51% above
Sulfate
58
2004–2017
100%
11% of limit
↓ 60% below
Nitrate
42
1976–2016
33%
0% of limit
↓ 99% below
Chloride
58
2004–2017
100%
14% of limit
↓ 61% below
Arsenic
182
1990–2020
21%
1% of limit
↓ 96% below
Fluoride
470
1938–2020
93%
8% of limit
↓ 69% below
HFPO-DA (GenX)
municipal
22
2023–2025
0%
—
—
Lead
181
1990–2020
13%
0% of limit
↓ 98% below
Nitrite
18
2004–2016
0%
—
—
PFHxS
municipal
22
2023–2025
0%
—
—
PFNA
municipal
22
2023–2025
0%
—
—
PFOA
municipal
22
2023–2025
0%
—
—
PFOS
municipal
22
2023–2025
0%
—
—
Radon
3
2008–2015
100%
16% of limit
↓ 56% below
Uranium
100
2004–2020
4%
1% of limit
↓ 92% below
Hardness
58
2004–2017
100%
—
↓ 70% below
PFBS
municipal
22
2023–2025
0%
—
—
pH
58
2004–2017
100%
—
~ typical
Sodium
58
2004–2017
100%
—
↓ 80% 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 Wilson County
Of the 182 arsenic tests on record for Wilson County (1990–2020),
79% found none.
Of the 58 chloride tests on record for Wilson County (2004–2017),
0% found none, and half were below 35.2 mg/L.
Of the 470 fluoride tests on record for Wilson County (1938–2020),
7% found none, and half were below 300 µg/L.
Of the 309 iron tests on record for Wilson County (1938–2020),
12% found none, and half were below 292 µg/L.
Of the 181 lead tests on record for Wilson County (1990–2020),
87% found none.
Of the 260 manganese tests on record for Wilson County (1938–2020),
28% found none, and half were below 25.6 µg/L.
Of the 42 nitrate tests on record for Wilson County (1976–2016),
67% found none.
Of the 58 sulfate tests on record for Wilson County (2004–2017),
0% found none, and half were below 28.4 mg/L.
Of the 100 uranium tests on record for Wilson County (2004–2020),
96% found none.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Iron 309 samples
Manganese 260 samples
Sulfate 58 samples
Nitrate 42 samples
Chloride 58 samples
Arsenic 182 samples
Fluoride 470 samples
Lead 181 samples
Nitrite 18 samples
Uranium 100 samples
Hardness 58 samples
pH 58 samples
Sodium 58 samples
Limited data (<15 samples) — interpret with caution
Radon 3 samples
No private-well PFAS data for Wilson County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Wilson 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 Wilson County
18Active public water systems
57,752Residents on public water
2%Households on private wells
Public water systems in Wilson 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 Wilson 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.
This report aggregates data from the following public databases:
Water Quality Portal (WQP) — groundwater sample results for Wilson County from EPA, USGS, and state agencies. Browse WQP data →
EPA Safe Drinking Water Information System (SDWIS) — public water system inventory used to estimate the share of residents on private wells. Browse SDWIS →
Census ACS 5-Year Estimates — well and cistern household counts (variable DP04_0074E) used to calculate the private-well percentage for Wilson County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Wilson County, which informs which contaminants are geologically likely. USGS Aquifer Atlas →
EPA UCMR 5 (2023–2025) — PFAS occurrence data from public water systems, used as a proxy indicator for aquifer PFAS exposure. Rows marked "municipal" in the table above come from this source. About UCMR 5 →
EPA Toxics Release Inventory (TRI) — industrial facility chemical releases near Wilson County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Wilson County, used in contamination risk scoring. Superfund site search →
CDC PLACES — county-level health outcome prevalence (kidney disease, cancer, heart disease) correlated with detected contaminants. About CDC PLACES →
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.