Full contaminant data, sample history, and sourcing for San Jacinto County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
228 well testing events on record, covering
20 analytes.
Data spans 1963 to 2014.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. TX Avg
Radon
9
2002–2014
100%
28% of limit
↓ 22% below
Manganese
74
1955–2021
88%
95% of limit
↑ 47% above
Iron
183
1945–2021
92%
37% of limit
↓ 76% below
Arsenic
74
1992–2021
59%
27% of limit
↓ 29% below
Chloride
21
1965–2014
100%
14% of limit
↓ 61% below
Fluoride
138
1955–2021
100%
8% of limit
↓ 69% below
HFPO-DA (GenX)
municipal
6
2023
0%
—
—
Lead
66
1992–2021
17%
1% of limit
↓ 92% below
Nitrate
34
1976–2014
41%
0% of limit
↓ 98% below
Nitrite
17
1994–2014
0%
—
—
PFHxS
municipal
6
2023
0%
—
—
PFNA
municipal
6
2023
0%
—
—
PFOA
municipal
6
2023
0%
—
—
PFOS
municipal
6
2023
0%
—
—
Sulfate
21
1965–2014
100%
5% of limit
↓ 83% below
Uranium
30
1994–2021
57%
3% of limit
↓ 79% below
Hardness
21
1965–2014
100%
—
↓ 58% below
PFBS
municipal
6
2023
0%
—
—
pH
21
1965–2014
100%
—
~ typical
Sodium
19
1976–2014
100%
—
~ 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 San Jacinto County
Of the 74 arsenic tests on record for San Jacinto County (1992–2021),
41% found none, and half were below 2 µg/L.
Of the 21 chloride tests on record for San Jacinto County (1965–2014),
0% found none, and half were below 34.6 mg/L.
Of the 138 fluoride tests on record for San Jacinto County (1955–2021),
0% found none, and half were below 300 µg/L.
Of the 183 iron tests on record for San Jacinto County (1945–2021),
8% found none, and half were below 95 µg/L.
Of the 66 lead tests on record for San Jacinto County (1992–2021),
83% found none.
Of the 74 manganese tests on record for San Jacinto County (1955–2021),
12% found none, and half were below 41.9 µg/L.
Of the 34 nitrate tests on record for San Jacinto County (1976–2014),
59% found none.
Of the 21 sulfate tests on record for San Jacinto County (1965–2014),
0% found none, and half were below 12 mg/L.
Of the 30 uranium tests on record for San Jacinto County (1994–2021),
43% found none, and half were below 0.166 µg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Manganese 74 samples
Iron 183 samples
Arsenic 74 samples
Chloride 21 samples
Fluoride 138 samples
Lead 66 samples
Nitrate 34 samples
Nitrite 17 samples
Sulfate 21 samples
Uranium 30 samples
Hardness 21 samples
pH 21 samples
Sodium 19 samples
Limited data (<15 samples) — interpret with caution
Radon 9 samples
No private-well PFAS data for San Jacinto County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in San Jacinto 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 San Jacinto County
37Active public water systems
33,111Residents on public water
20%Households on private wells
Public water systems in San Jacinto 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 San Jacinto 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 San Jacinto 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 San Jacinto County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying San Jacinto 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 San Jacinto County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near San Jacinto 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.