Data & Methodology — Hernando County Well Water

Contaminant Data — All Analytes

1836 well testing events on record, covering 23 analytes. Data spans 1956 to 2025.

Contaminant	Samples	Years	Detection Rate	vs. Limit	vs. FL Avg
Radon	1	2015	100%	157% of limit	↑ 434% above
Chloride	1693	1962–2025	100%	10% of limit	↓ 80% below
PFOS municipal	37	2023–2025	30%	160% of limit	↓ 24% below
Sulfate	1160	1962–2025	100%	5% of limit	↓ 81% below
Iron	1008	1962–2025	99%	6% of limit	↓ 97% below
Arsenic	34	1977–2024	97%	2% of limit	↓ 81% below
PFOA municipal	37	2023–2025	8%	110% of limit	↓ 23% below
Manganese	909	1977–2025	99%	4% of limit	↓ 84% below
Fluoride	931	1962–2025	99%	2% of limit	↓ 68% below
HFPO-DA (GenX) municipal	37	2023–2025	0%	—	—
Nitrite	475	1971–2024	99%	0% of limit	↓ 90% below
PFNA municipal	37	2023–2025	0%	—	—
Lead	37	1977–2024	78%	1% of limit	↓ 58% below
Nitrate	17	1962–2015	100%	1% of limit	↓ 60% below
PFHxS municipal	37	2023–2025	3%	33% of limit	↓ 36% below
Uranium	3	2002–2015	100%	4% of limit	↑ 261% above
Hardness	120	1962–2015	100%	—	↓ 36% below
Total Coliform	49	1985–2025	97%	—	~ typical
E. coli	20	2002–2025	96%	—	~ typical
Fecal Coliform	29	1985–2021	96%	—	~ typical
PFBS municipal	37	2023–2025	49%	—	~ typical
pH	969	1962–2025	100%	—	~ typical
Sodium	1058	1962–2025	100%	—	↓ 87% below

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)

Chloride 1693 samples
Sulfate 1160 samples
Iron 1008 samples
Arsenic 34 samples
Manganese 909 samples
Fluoride 931 samples
Nitrite 475 samples
Lead 37 samples
Nitrate 17 samples
Hardness 120 samples
Total Coliform 49 samples
E. coli 20 samples
Fecal Coliform 29 samples
pH 969 samples
Sodium 1058 samples

Limited data (<15 samples) — interpret with caution

Radon 1 sample
Uranium 3 samples

No private-well PFAS data for Hernando County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Hernando 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 Hernando County

113 Active public water systems

178,191 Residents on public water

Public water systems in Hernando 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 Hernando 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	Hernando County Prevalence	FL Average	Source Year
Arsenic	Cancer prevalence	8.9%	6.8%	2020
Arsenic	Kidney disease rate	4.1%	3.4%	2020

Data Sources

This report aggregates data from the following public databases:

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