Full contaminant data, sample history, and sourcing for Fairfield County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
177 well testing events on record, covering
20 analytes.
Data spans 1962 to 2023.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. OH Avg
Iron
161
1973–2023
99%
568% of limit
↑ 30% above
Manganese
145
1973–2023
98%
244% of limit
↑ 38% above
Arsenic
123
1992–2023
98%
70% of limit
↑ 344% above
Lead
130
1975–2023
76%
0% of limit
↓ 100% below
Chloride
166
1973–2023
99%
16% of limit
~ typical
Fluoride
111
1973–2023
79%
7% of limit
↓ 28% below
HFPO-DA (GenX)
municipal
10
2023–2025
0%
—
—
Nitrate
24
1974–2023
88%
1% of limit
↓ 79% below
Nitrite
18
1974–2023
78%
0% of limit
↓ 100% below
PFHxS
municipal
10
2023–2025
0%
—
—
PFNA
municipal
10
2023–2025
0%
—
—
PFOA
municipal
10
2023–2025
0%
—
—
PFOS
municipal
10
2023–2025
0%
—
—
Radon
2
2013
100%
88% of limit
↑ 297% above
Sulfate
32
1978–2023
100%
19% of limit
↓ 56% below
Uranium
3
2013–2023
100%
7% of limit
↑ 185% above
Sodium
167
1973–2023
100%
—
↓ 28% below
pH
108
1973–2023
100%
—
~ typical
PFBS
municipal
10
2023–2025
0%
—
—
Hardness
115
1973–2023
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 OH.
Compare your result with Fairfield County
Of the 123 arsenic tests on record for Fairfield County (1992–2023),
2% found none, and half were below 7 µg/L.
Of the 166 chloride tests on record for Fairfield County (1973–2023),
1% found none, and half were below 39.9 mg/L.
Of the 111 fluoride tests on record for Fairfield County (1973–2023),
21% found none, and half were below 170 µg/L.
Of the 161 iron tests on record for Fairfield County (1973–2023),
1% found none, and half were below 1.7 mg/L.
Of the 130 lead tests on record for Fairfield County (1975–2023),
24% found none.
Of the 145 manganese tests on record for Fairfield County (1973–2023),
2% found none, and half were below 121 µg/L.
Of the 24 nitrate tests on record for Fairfield County (1974–2023),
12% found none, and half were below 100 µg/L.
Of the 32 sulfate tests on record for Fairfield County (1978–2023),
0% found none, and half were below 48.1 mg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Iron 161 samples
Manganese 145 samples
Arsenic 123 samples
Lead 130 samples
Chloride 166 samples
Fluoride 111 samples
Nitrate 24 samples
Nitrite 18 samples
Sulfate 32 samples
Sodium 167 samples
pH 108 samples
Hardness 115 samples
Limited data (<15 samples) — interpret with caution
Radon 2 samples
Uranium 3 samples
No private-well PFAS data for Fairfield County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Fairfield 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 Fairfield County
74Active public water systems
99,693Residents on public water
40%Households on private wells
Public water systems in Fairfield 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 Fairfield 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 Fairfield 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 Fairfield County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Fairfield 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 Fairfield County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Fairfield 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 OH with at least one sample for that analyte.