Full contaminant data, sample history, and sourcing for Duval County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
5897 well testing events on record, covering
23 analytes.
Data spans 1925 to 2023.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. FL Avg
Manganese
1096
1952–2024
99%
15% of limit
↓ 43% below
Iron
1247
1925–2024
99%
8% of limit
↓ 96% below
Sulfate
1151
1925–2024
100%
54% of limit
↑ 104% above
Chloride
5554
1925–2024
100%
10% of limit
↓ 79% below
Arsenic
1056
1979–2024
100%
4% of limit
↓ 66% below
Fluoride
894
1941–2024
98%
16% of limit
↑ 129% above
PFNA
municipal
82
2023–2025
0%
—
—
PFOA
municipal
82
2023–2025
0%
—
—
HFPO-DA (GenX)
municipal
82
2023–2025
0%
—
—
Nitrite
313
1973–2015
29%
0% of limit
↓ 84% below
Lead
1059
1966–2024
100%
0% of limit
↓ 113% below
Nitrate
358
1940–2015
37%
1% of limit
↓ 83% below
PFHxS
municipal
82
2023–2025
0%
—
—
PFOS
municipal
82
2023–2025
0%
—
—
Radon
1
2015
100%
20% of limit
↓ 32% below
Uranium
3
2005–2015
0%
—
—
Total Coliform
15
2005–2024
94%
—
~ typical
Hardness
1431
1925–2015
100%
—
↑ 25% above
E. coli
3
2005–2024
57%
—
~ typical
Fecal Coliform
12
2006–2021
15%
—
~ typical
PFBS
municipal
82
2023–2025
0%
—
—
Sodium
1961
1930–2024
100%
—
↓ 74% below
pH
2328
1951–2024
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 FL.
Compare your result with Duval County
Of the 1056 arsenic tests on record for Duval County (1979–2024),
0% found none, and half were below 0.439 µg/L.
Of the 5554 chloride tests on record for Duval County (1925–2024),
0% found none, and half were below 26 mg/L.
Of the 894 fluoride tests on record for Duval County (1941–2024),
2% found none, and half were below 630 µg/L.
Of the 1247 iron tests on record for Duval County (1925–2024),
1% found none, and half were below 23.1 µg/L.
Of the 1059 lead tests on record for Duval County (1966–2024),
0% found none.
Of the 1096 manganese tests on record for Duval County (1952–2024),
1% found none, and half were below 7.49 µg/L.
Of the 358 nitrate tests on record for Duval County (1940–2015),
63% found none.
Of the 1151 sulfate tests on record for Duval County (1925–2024),
0% found none, and half were below 134 mg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Manganese 1096 samples
Iron 1247 samples
Sulfate 1151 samples
Chloride 5554 samples
Arsenic 1056 samples
Fluoride 894 samples
Nitrite 313 samples
Lead 1059 samples
Nitrate 358 samples
Total Coliform 15 samples
Hardness 1431 samples
Sodium 1961 samples
pH 2328 samples
Limited data (<15 samples) — interpret with caution
Radon 1 sample
Uranium 3 samples
E. coli 3 samples
Fecal Coliform 12 samples
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
92Active public water systems
938,721Residents on public water
16%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 FL with at least one sample for that analyte.