Data & Methodology — Sumter County Well Water

Contaminant Data — All Analytes

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

Contaminant	Samples	Years	Detection Rate	vs. Limit	vs. FL Avg
PFOS municipal	36	2023–2025	31%	132% of limit	↓ 37% below
PFOA municipal	36	2023–2025	28%	130% of limit	~ typical
Iron	273	1966–2025	99%	3% of limit	↓ 99% below
PFHxS municipal	36	2023–2025	17%	98% of limit	↑ 90% above
Lead	27	1994–2024	93%	3% of limit	~ typical
Sulfate	356	1966–2025	98%	8% of limit	↓ 71% below
Manganese	252	1992–2025	99%	1% of limit	↓ 97% below
Radon	3	2002	100%	10% of limit	↓ 66% below
Uranium	4	2002–2010	100%	1% of limit	↓ 21% below
Fluoride	309	1966–2025	98%	3% of limit	↓ 61% below
HFPO-DA (GenX) municipal	36	2023–2025	0%	—	—
Nitrite	225	1974–2024	82%	0% of limit	↓ 90% below
Nitrate	57	1966–2012	49%	3% of limit	~ typical
Arsenic	27	1994–2024	96%	2% of limit	↓ 81% below
Chloride	355	1966–2025	100%	4% of limit	↓ 92% below
PFNA municipal	36	2023–2025	0%	—	—
pH	354	1966–2025	100%	—	~ typical
Sodium	356	1966–2025	100%	—	↓ 92% below
Hardness	88	1966–2012	100%	—	~ typical
Total Coliform	43	2002–2025	98%	—	~ typical
E. coli	20	2002–2025	100%	—	~ typical
Fecal Coliform	23	2013–2021	100%	—	~ typical
PFBS municipal	36	2023–2025	61%	—	↑ 47% 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 FL.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

Iron 273 samples
Lead 27 samples
Sulfate 356 samples
Manganese 252 samples
Fluoride 309 samples
Nitrite 225 samples
Nitrate 57 samples
Arsenic 27 samples
Chloride 355 samples
pH 354 samples
Sodium 356 samples
Hardness 88 samples
Total Coliform 43 samples
E. coli 20 samples
Fecal Coliform 23 samples

Limited data (<15 samples) — interpret with caution

Radon 3 samples
Uranium 4 samples

No private-well PFAS data for Sumter County

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

82 Active public water systems

174,314 Residents on public water

Public water systems in Sumter 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 Sumter 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	Sumter County Prevalence	FL Average	Source Year
Lead	Heart disease rate	13.4%	7.7%	2020
PFOA	Cancer prevalence	6.0%	6.8%	2020

Data Sources

This report aggregates data from the following public databases:

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