Data & Methodology — York County

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

Contaminant Data — All Analytes

416 well testing events on record, covering 22 analytes. Data spans 1925 to 2023.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. PA Avg
Radon 66 1986–2021 100%
460% of limit ↑ 256% above
Manganese 224 1960–2023 87%
40% of limit ↓ 92% below
PFOS municipal 500 2023–2025 49%
103% of limit ~ typical
PFOA municipal 500 2023–2025 56%
90% of limit ~ typical
Iron 228 1925–2023 93%
30% of limit ↓ 95% below
Nitrate 215 1925–2023 98%
43% of limit ↑ 142% above
Chloride 240 1925–2023 100%
3% of limit ↓ 70% below
Sulfate 236 1925–2023 94%
4% of limit ↓ 77% below
HFPO-DA (GenX) municipal 493 2023–2025 0%
— —
Fluoride 229 1960–2023 66%
2% of limit ↓ 44% below
Nitrite 105 1976–2023 10%
1% of limit ↓ 33% below
Uranium 61 1986–2021 59%
1% of limit ↓ 71% below
Arsenic 67 1972–2023 66%
10% of limit ↓ 66% below
Lead 97 1968–2023 30%
0% of limit ↓ 100% below
PFHxS municipal 101 2023–2025 6%
35% of limit ↓ 24% below
PFNA municipal 101 2023–2025 1%
62% of limit ~ typical
Total Coliform 4 1993–2021 36%
— ~ typical
Hardness 236 1925–2023 99%
— ↓ 63% below
E. coli 4 1994–2021 0%
— —
PFBS municipal 493 2023–2025 57%
— ~ typical
pH 250 1960–2023 100%
— ~ typical
Sodium 235 1925–2023 100%
— ↓ 66% below

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 York County

Of the 67 arsenic tests on record for York County (1972–2023), 34% found none, and half were below 1 µg/L.

Of the 240 chloride tests on record for York County (1925–2023), 0% found none, and half were below 8 mg/L.

Of the 229 fluoride tests on record for York County (1960–2023), 34% found none.

Of the 228 iron tests on record for York County (1925–2023), 7% found none, and half were below 70 µg/L.

Of the 97 lead tests on record for York County (1968–2023), 70% found none.

Of the 224 manganese tests on record for York County (1960–2023), 13% found none, and half were below 20 µg/L.

Of the 215 nitrate tests on record for York County (1925–2023), 2% found none, and half were below 4.3 mg/L.

Of the 399 pfoa tests on record for York County (2025), 35% found none, and half were below 2.3 ng/L.

Of the 399 pfos tests on record for York County (2025), 44% found none, and half were below 2 ng/L.

Of the 236 sulfate tests on record for York County (1925–2023), 6% found none, and half were below 8.5 mg/L.

Of the 61 uranium tests on record for York County (1986–2021), 41% found none, and half were below 20 ng/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Radon 66 samples
  • Manganese 224 samples
  • PFOS 500 samples
  • PFOA 500 samples
  • Iron 228 samples
  • Nitrate 215 samples
  • Chloride 240 samples
  • Sulfate 236 samples
  • HFPO-DA (GenX) 493 samples
  • Fluoride 229 samples
  • Nitrite 105 samples
  • Uranium 61 samples
  • Arsenic 67 samples
  • Lead 97 samples
  • Hardness 236 samples
  • PFBS 493 samples
  • pH 250 samples
  • Sodium 235 samples

Limited data (<15 samples) — interpret with caution

  • Total Coliform 4 samples
  • E. coli 4 samples

Public vs. Private Water in York County

208 Active public water systems
390,208 Residents on public water
37% Households on private wells

Public water systems in York 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 York 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 York County Prevalence PA Average Source Year
Nitrate Cancer prevalence 7.4% 7.0% 2020

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