Data & Methodology — Tioga County

Full contaminant data, sample history, and sourcing for Tioga County. For readers who want to go beyond the summary.

Contaminant Data — All Analytes

419 well testing events on record, covering 22 analytes. Data spans 1928 to 2023.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. PA Avg
Radon 12 2010–2022 100%
423% of limit ↑ 227% above
Manganese 173 1973–2023 85%
500% of limit ~ typical
Iron 181 1935–2023 89%
217% of limit ↓ 63% below
Arsenic 197 1974–2023 41%
30% of limit ~ typical
Lead 166 1973–2023 11%
1% of limit ↓ 76% below
Chloride 176 1935–2023 100%
3% of limit ↓ 71% below
Fluoride 172 1973–2023 79%
2% of limit ↓ 44% below
HFPO-DA (GenX) municipal 71 2024–2025 0%
— —
Nitrate 178 1935–2023 95%
2% of limit ↓ 88% below
Nitrite 171 1973–2023 60%
0% of limit ↓ 93% below
PFHxS municipal 8 2024–2025 0%
— —
PFNA municipal 8 2024–2025 0%
— —
PFOA municipal 95 2024–2025 0%
— —
PFOS municipal 95 2024–2025 4%
49% of limit ↓ 62% below
Sulfate 176 1935–2023 93%
5% of limit ↓ 72% below
Uranium 26 2010–2022 54%
0% of limit ↓ 92% below
E. coli 1 1998–2022 50%
— ~ typical
Hardness 142 1935–2023 100%
— ~ typical
PFBS municipal 71 2024–2025 0%
— —
pH 284 1973–2023 100%
— ~ typical
Sodium 172 1935–2023 99%
— ↓ 64% below
Total Coliform 1 1998–2022 75%
— ~ 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 PA.

Compare your result with Tioga County

Of the 197 arsenic tests on record for Tioga County (1974–2023), 59% found none.

Of the 176 chloride tests on record for Tioga County (1935–2023), 0% found none, and half were below 7.75 mg/L.

Of the 172 fluoride tests on record for Tioga County (1973–2023), 21% found none, and half were below 100 µg/L.

Of the 181 iron tests on record for Tioga County (1935–2023), 11% found none, and half were below 500 µg/L.

Of the 166 lead tests on record for Tioga County (1973–2023), 89% found none.

Of the 173 manganese tests on record for Tioga County (1973–2023), 15% found none, and half were below 100 µg/L.

Of the 178 nitrate tests on record for Tioga County (1935–2023), 5% found none, and half were below 200 µg/L.

Of the 87 pfoa tests on record for Tioga County (2025), 100% found none.

Of the 87 pfos tests on record for Tioga County (2025), 95% found none.

Of the 176 sulfate tests on record for Tioga County (1935–2023), 7% found none, and half were below 10 mg/L.

Of the 26 uranium tests on record for Tioga County (2010–2022), 46% found none, and half were below 10.5 ng/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 173 samples
  • Iron 181 samples
  • Arsenic 197 samples
  • Lead 166 samples
  • Chloride 176 samples
  • Fluoride 172 samples
  • HFPO-DA (GenX) 71 samples
  • Nitrate 178 samples
  • Nitrite 171 samples
  • PFOA 95 samples
  • PFOS 95 samples
  • Sulfate 176 samples
  • Uranium 26 samples
  • Hardness 142 samples
  • PFBS 71 samples
  • pH 284 samples
  • Sodium 172 samples

Limited data (<15 samples) — interpret with caution

  • Radon 12 samples
  • E. coli 1 sample
  • Total Coliform 1 sample

Public vs. Private Water in Tioga County

84 Active public water systems
33,215 Residents on public water
64% Households on private wells

Public water systems in Tioga 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 Tioga 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 Tioga County Prevalence PA Average Source Year
Arsenic Cancer incidence rate 436.7% 448.6% 2022
Arsenic Cancer prevalence 8.3% 7.0% 2020
Arsenic Kidney disease rate 3.5% 3.0% 2020
Lead Heart disease rate 6.5% 7.2% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Tioga County CDC PLACES data →

Data Sources

This report aggregates data from the following public databases:

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.

Last updated: 2026-08-04

Full methodology →