Data & Methodology — Pinellas County Well Water

Contaminant Data — All Analytes

5865 well testing events on record, covering 22 analytes. Data spans 1917 to 2025.

Contaminant	Samples	Years	Detection Rate	vs. Limit	vs. FL Avg
Iron	896	1917–2025	98%	402% of limit	↑ 99% above
Chloride	5280	1949–2025	100%	136% of limit	↑ 178% above
Sulfate	1402	1949–2025	99%	18% of limit	↓ 30% below
Manganese	437	1971–2025	95%	43% of limit	↑ 61% above
PFOS municipal	64	2023–2025	9%	840% of limit	↑ 298% above
Arsenic	1145	1971–2024	80%	30% of limit	↑ 130% above
PFOA municipal	64	2023–2025	8%	242% of limit	↑ 70% above
Nitrate	1760	1949–2002	97%	0% of limit	↓ 94% below
Lead	788	1917–2024	11%	0% of limit	↓ 100% below
Fluoride	757	1949–2025	94%	6% of limit	↓ 23% below
Nitrite	1798	1971–2022	56%	1% of limit	~ typical
HFPO-DA (GenX) municipal	64	2023–2025	0%	—	—
Uranium	2	2002	50%	0% of limit	↓ 96% below
PFHxS municipal	64	2023–2025	6%	76% of limit	↑ 47% above
PFNA municipal	64	2023–2025	0%	—	—
pH	2297	1949–2025	100%	—	~ typical
Sodium	1874	1917–2025	100%	—	↑ 25% above
Hardness	1607	1949–2002	100%	—	↑ 42% above
Total Coliform	17	1973–2024	60%	—	~ typical
E. coli	7	2002–2024	100%	—	~ typical
Fecal Coliform	10	1973–2021	33%	—	~ typical
PFBS municipal	64	2023–2025	11%	—	~ 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.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

Iron 896 samples
Chloride 5280 samples
Sulfate 1402 samples
Manganese 437 samples
Arsenic 1145 samples
Nitrate 1760 samples
Lead 788 samples
Fluoride 757 samples
Nitrite 1798 samples
pH 2297 samples
Sodium 1874 samples
Hardness 1607 samples
Total Coliform 17 samples

Limited data (<15 samples) — interpret with caution

Uranium 2 samples
E. coli 7 samples
Fecal Coliform 10 samples

No private-well PFAS data for Pinellas County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Pinellas County. PFAS has been detected in local public water systems (UCMR 5 data) — indicated by the "municipal" badge in the table above — but this does not directly indicate private well contamination. 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 Pinellas County

13 Active public water systems

1,147,926 Residents on public water

Public water systems in Pinellas 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 Pinellas 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.

Contaminant	Associated Condition	Pinellas County Prevalence	FL Average	Source Year
Arsenic	Cancer prevalence	8.6%	6.8%	2020
Arsenic	Kidney disease rate	3.7%	3.4%	2020
Lead	Heart disease rate	5.8%	7.7%	2020

Data Sources

This report aggregates data from the following public databases:

Water Quality Portal (WQP) — groundwater sample results for Pinellas 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 Pinellas County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Pinellas 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 Pinellas County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Pinellas 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.

Last updated: 2026-08-12

Full methodology →