Full contaminant data, sample history, and sourcing for Duval County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
508 well testing events on record, covering
20 analytes.
Data spans 1913 to 2013.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. TX Avg
Radon
1
2013
100%
127% of limit
↑ 252% above
Chloride
92
1913–2013
100%
188% of limit
↑ 426% above
Arsenic
193
1977–2021
88%
142% of limit
↑ 272% above
Nitrate
108
1913–2013
100%
140% of limit
↑ 529% above
Sulfate
92
1913–2013
100%
50% of limit
↑ 74% above
Iron
287
1913–2021
43%
40% of limit
↓ 74% below
Manganese
232
1960–2021
32%
10% of limit
↓ 85% below
Fluoride
488
1913–2021
100%
25% of limit
~ typical
HFPO-DA (GenX)
municipal
2
2025
0%
—
—
Lead
190
1977–2021
6%
11% of limit
↓ 37% below
Nitrite
1
2013
0%
—
—
PFHxS
municipal
2
2025
0%
—
—
PFNA
municipal
2
2025
0%
—
—
PFOA
municipal
2
2025
0%
—
—
PFOS
municipal
2
2025
0%
—
—
Uranium
73
1990–2021
97%
25% of limit
↑ 63% above
Hardness
87
1913–2013
100%
—
~ typical
PFBS
municipal
2
2025
0%
—
—
pH
80
1945–2013
100%
—
~ typical
Sodium
92
1913–2013
100%
—
↑ 180% 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 Duval County
Of the 193 arsenic tests on record for Duval County (1977–2021),
12% found none, and half were below 12.4 µg/L.
Of the 92 chloride tests on record for Duval County (1913–2013),
0% found none, and half were below 470 mg/L.
Of the 488 fluoride tests on record for Duval County (1913–2021),
0% found none, and half were below 1 mg/L.
Of the 287 iron tests on record for Duval County (1913–2021),
57% found none.
Of the 190 lead tests on record for Duval County (1977–2021),
94% found none.
Of the 232 manganese tests on record for Duval County (1960–2021),
68% found none.
Of the 108 nitrate tests on record for Duval County (1913–2013),
0% found none, and half were below 14 mg/L.
Of the 92 sulfate tests on record for Duval County (1913–2013),
0% found none, and half were below 124 mg/L.
Of the 73 uranium tests on record for Duval County (1990–2021),
3% found none, and half were below 7.01 µg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Chloride 92 samples
Arsenic 193 samples
Nitrate 108 samples
Sulfate 92 samples
Iron 287 samples
Manganese 232 samples
Fluoride 488 samples
Lead 190 samples
Uranium 73 samples
Hardness 87 samples
pH 80 samples
Sodium 92 samples
Limited data (<15 samples) — interpret with caution
Radon 1 sample
Nitrite 1 sample
No private-well PFAS data for Duval County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Duval 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 Duval County
9Active public water systems
12,532Residents on public water
15%Households on private wells
Public water systems in Duval 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 Duval 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 Duval 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 Duval County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Duval 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 Duval County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Duval 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.