Full contaminant data, sample history, and sourcing for Clearfield County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
630 well testing events on record, covering
20 analytes.
Data spans 1901 to 2024.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. PA Avg
Manganese
585
1901–2023
100%
74000% of limit
↑ 14577% above
Iron
588
1901–2023
98%
13333% of limit
↑ 2194% above
Sulfate
585
1901–2023
100%
560% of limit
↑ 3170% above
Radon
9
1995–2018
100%
7% of limit
↓ 94% below
Uranium
13
1996–2021
54%
3% of limit
↑ 45% above
Nitrate
588
1901–2023
44%
3% of limit
↓ 83% below
Lead
568
1901–2023
3%
5333% of limit
↑ 115201% above
Arsenic
574
1901–2023
5%
10% of limit
↓ 66% below
Chloride
589
1901–2023
94%
1% of limit
↓ 89% below
Fluoride
567
1901–2023
63%
15% of limit
↑ 236% above
HFPO-DA (GenX)
municipal
36
2023–2025
0%
—
—
Nitrite
582
1901–2023
62%
1% of limit
↓ 47% below
PFHxS
municipal
27
2023–2025
0%
—
—
PFNA
municipal
26
2023–2025
0%
—
—
PFOA
municipal
47
2023–2025
0%
—
—
PFOS
municipal
47
2023–2025
0%
—
—
Sodium
584
1901–2023
100%
—
↓ 61% below
pH
586
1901–2023
100%
—
↓ 34% below
PFBS
municipal
37
2023–2025
0%
—
—
Hardness
589
1901–2023
100%
—
↑ 577% 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 PA.
Compare your result with Clearfield County
Of the 574 arsenic tests on record for Clearfield County (1901–2023),
95% found none.
Of the 589 chloride tests on record for Clearfield County (1901–2023),
6% found none, and half were below 3 mg/L.
Of the 567 fluoride tests on record for Clearfield County (1901–2023),
37% found none, and half were below 300 µg/L.
Of the 588 iron tests on record for Clearfield County (1901–2023),
2% found none, and half were below 37.5 mg/L.
Of the 568 lead tests on record for Clearfield County (1901–2023),
97% found none.
Of the 585 manganese tests on record for Clearfield County (1901–2023),
0% found none, and half were below 37 mg/L.
Of the 588 nitrate tests on record for Clearfield County (1901–2023),
56% found none.
Of the 20 pfoa tests on record for Clearfield County (2025),
100% found none.
Of the 20 pfos tests on record for Clearfield County (2025),
100% found none.
Of the 585 sulfate tests on record for Clearfield County (1901–2023),
0% found none, and half were below 1400 mg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Manganese 585 samples
Iron 588 samples
Sulfate 585 samples
Nitrate 588 samples
Lead 568 samples
Arsenic 574 samples
Chloride 589 samples
Fluoride 567 samples
HFPO-DA (GenX) 36 samples
Nitrite 582 samples
PFOA 47 samples
PFOS 47 samples
Sodium 584 samples
pH 586 samples
PFBS 37 samples
Hardness 589 samples
Limited data (<15 samples) — interpret with caution
Radon 9 samples
Uranium 13 samples
Public vs. Private Water in Clearfield County
37Active public water systems
56,946Residents on public water
28%Households on private wells
Public water systems in Clearfield 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 Clearfield 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 Clearfield 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 Clearfield County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Clearfield 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 Clearfield County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Clearfield 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 PA with at least one sample for that analyte.