Full contaminant data, sample history, and sourcing for Uvalde County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
1006 well testing events on record, covering
22 analytes.
Data spans 1930 to 2023.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. TX Avg
Sulfate
489
1930–2022
100%
11% of limit
↓ 61% below
Chloride
492
1930–2022
100%
14% of limit
↓ 60% below
Radon
26
1996–2017
100%
8% of limit
↓ 77% below
Iron
526
1930–2022
40%
4% of limit
↓ 97% below
Nitrate
318
1930–2022
94%
20% of limit
~ typical
Manganese
491
1938–2022
22%
4% of limit
↓ 94% below
Fluoride
704
1938–2022
96%
5% of limit
↓ 79% below
Lead
443
1970–2022
30%
8% of limit
↓ 51% below
Arsenic
579
1970–2022
32%
10% of limit
↓ 74% below
HFPO-DA (GenX)
municipal
17
2024
0%
—
—
Nitrite
239
1977–2022
18%
1% of limit
~ typical
PFHxS
municipal
17
2024
0%
—
—
PFNA
municipal
17
2024
0%
—
—
PFOA
municipal
17
2024
0%
—
—
PFOS
municipal
17
2024
0%
—
—
Uranium
129
1996–2022
47%
3% of limit
↓ 84% below
Hardness
485
1930–2022
100%
—
~ typical
Total Coliform
12
1970–2018
52%
—
~ typical
E. coli
12
2004–2018
52%
—
~ typical
Sodium
341
1945–2022
100%
—
↓ 87% below
pH
491
1945–2022
100%
—
~ typical
PFBS
municipal
17
2024
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 Uvalde County
Of the 579 arsenic tests on record for Uvalde County (1970–2022),
68% found none.
Of the 492 chloride tests on record for Uvalde County (1930–2022),
0% found none, and half were below 36 mg/L.
Of the 704 fluoride tests on record for Uvalde County (1938–2022),
4% found none, and half were below 200 µg/L.
Of the 526 iron tests on record for Uvalde County (1930–2022),
60% found none.
Of the 443 lead tests on record for Uvalde County (1970–2022),
70% found none.
Of the 491 manganese tests on record for Uvalde County (1938–2022),
78% found none.
Of the 318 nitrate tests on record for Uvalde County (1930–2022),
6% found none, and half were below 1.9 mg/L.
Of the 489 sulfate tests on record for Uvalde County (1930–2022),
0% found none, and half were below 28 mg/L.
Of the 129 uranium tests on record for Uvalde County (1996–2022),
53% found none.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Sulfate 489 samples
Chloride 492 samples
Radon 26 samples
Iron 526 samples
Nitrate 318 samples
Manganese 491 samples
Fluoride 704 samples
Lead 443 samples
Arsenic 579 samples
Nitrite 239 samples
Uranium 129 samples
Hardness 485 samples
Sodium 341 samples
pH 491 samples
Limited data (<15 samples) — interpret with caution
Total Coliform 12 samples
E. coli 12 samples
No private-well PFAS data for Uvalde County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Uvalde 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 Uvalde County
30Active public water systems
30,707Residents on public water
13%Households on private wells
Public water systems in Uvalde 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 Uvalde 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 Uvalde 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 Uvalde County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Uvalde 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 Uvalde County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Uvalde 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.