Data & Methodology — Lake County Well Water

Contaminant Data — All Analytes

712 well testing events on record, covering 23 analytes. Data spans 1948 to 2017.

Contaminant	Samples	Years	Detection Rate	vs. Limit	vs. FL Avg
PFOS municipal	83	2023–2025	43%	150% of limit	↓ 29% below
Iron	630	1968–2025	99%	7% of limit	↓ 96% below
PFOA municipal	83	2023–2025	20%	128% of limit	~ typical
Chloride	655	1968–2025	100%	5% of limit	↓ 90% below
Manganese	580	1977–2025	99%	6% of limit	↓ 79% below
Nitrate	35	1968–2015	60%	4% of limit	~ typical
Sulfate	578	1968–2025	98%	4% of limit	↓ 85% below
PFHxS municipal	83	2023–2025	39%	37% of limit	↓ 28% below
Arsenic	576	1977–2025	97%	5% of limit	↓ 62% below
Lead	579	1977–2025	96%	0% of limit	↓ 89% below
Radon	3	2002–2015	100%	16% of limit	↓ 44% below
Uranium	3	2002–2015	67%	1% of limit	↓ 27% below
PFNA municipal	83	2023–2025	1%	40% of limit	↓ 31% below
Fluoride	129	1968–2025	83%	3% of limit	↓ 59% below
HFPO-DA (GenX) municipal	83	2023–2025	0%	—	—
Nitrite	33	1972–2015	39%	2% of limit	↑ 92% above
pH	660	1968–2025	100%	—	~ typical
Sodium	655	1968–2025	100%	—	↓ 91% below
Hardness	58	1968–2015	100%	—	↓ 44% below
Total Coliform	44	1973–2025	98%	—	~ typical
E. coli	19	2015–2025	95%	—	~ typical
Fecal Coliform	25	1977–2021	100%	—	~ typical
PFBS municipal	83	2023–2025	42%	—	~ 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 630 samples
Chloride 655 samples
Manganese 580 samples
Nitrate 35 samples
Sulfate 578 samples
Arsenic 576 samples
Lead 579 samples
Fluoride 129 samples
Nitrite 33 samples
pH 660 samples
Sodium 655 samples
Hardness 58 samples
Total Coliform 44 samples
E. coli 19 samples
Fecal Coliform 25 samples

Limited data (<15 samples) — interpret with caution

Radon 3 samples
Uranium 3 samples

No private-well PFAS data for Lake County

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

274 Active public water systems

431,469 Residents on public water

Public water systems in Lake 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 Lake 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	Lake County Prevalence	FL Average	Source Year
Arsenic	Cancer prevalence	8.7%	6.8%	2020
Arsenic	Kidney disease rate	3.8%	3.4%	2020
Lead	Heart disease rate	6.1%	7.7%	2020

Data Sources

This report aggregates data from the following public databases:

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