Data & Methodology — Erie County

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

Contaminant Data — All Analytes

609 well testing events on record, covering 19 analytes. Data spans 1927 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. PA Avg
Manganese 113 1964–1996 54%
340% of limit ↓ 33% below
Iron 312 1927–1996 92%
63% of limit ↓ 89% below
Arsenic 76 1987–1989 29%
170% of limit ↑ 481% above
Lead 84 1964–1989 10%
1333% of limit ↑ 28725% above
Chloride 432 1927–1996 100%
6% of limit ↓ 44% below
PFOA municipal 201 2023–2025 7%
106% of limit ~ typical
PFOS municipal 201 2023–2025 10%
84% of limit ↓ 34% below
Nitrate 164 1927–2004 65%
6% of limit ↓ 63% below
Nitrite 108 1987–2004 19%
2% of limit ~ typical
Fluoride 116 1951–1996 65%
5% of limit ~ typical
HFPO-DA (GenX) municipal 149 2023–2025 1%
23% of limit ~ typical
PFHxS municipal 45 2023–2025 0%
— —
PFNA municipal 45 2023–2025 0%
— —
Radon 5 1996 100%
6% of limit ↓ 95% below
Sulfate 102 1928–1996 99%
13% of limit ↓ 25% below
Sodium 122 1928–1996 100%
— ↓ 25% below
pH 276 1927–2023 100%
— ~ typical
PFBS municipal 151 2023–2025 10%
— ~ typical
Hardness 419 1927–1996 99%
— ~ 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 Erie County

Of the 76 arsenic tests on record for Erie County (1987–1989), 71% found none.

Of the 432 chloride tests on record for Erie County (1927–1996), 0% found none, and half were below 15 mg/L.

Of the 116 fluoride tests on record for Erie County (1951–1996), 35% found none, and half were below 100 µg/L.

Of the 312 iron tests on record for Erie County (1927–1996), 8% found none, and half were below 170 µg/L.

Of the 84 lead tests on record for Erie County (1964–1989), 90% found none.

Of the 113 manganese tests on record for Erie County (1964–1996), 46% found none, and half were below 40 µg/L.

Of the 164 nitrate tests on record for Erie County (1927–2004), 35% found none, and half were below 90 µg/L.

Of the 156 pfoa tests on record for Erie County (2025), 90% found none.

Of the 156 pfos tests on record for Erie County (2025), 87% found none.

Of the 102 sulfate tests on record for Erie County (1928–1996), 1% found none, and half were below 32 mg/L.

Have a number from your lab? Enter it to see where it falls. Nothing is sent anywhere.

Want the full picture for your well? Check all your results.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 113 samples
  • Iron 312 samples
  • Arsenic 76 samples
  • Lead 84 samples
  • Chloride 432 samples
  • PFOA 201 samples
  • PFOS 201 samples
  • Nitrate 164 samples
  • Nitrite 108 samples
  • Fluoride 116 samples
  • HFPO-DA (GenX) 149 samples
  • Sulfate 102 samples
  • Sodium 122 samples
  • pH 276 samples
  • PFBS 151 samples
  • Hardness 419 samples

Limited data (<15 samples) — interpret with caution

  • Radon 5 samples

Public vs. Private Water in Erie County

145 Active public water systems
305,482 Residents on public water
30% Households on private wells

Public water systems in Erie 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 Erie 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 Erie County Prevalence PA Average Source Year
Lead Heart disease rate 7.8% 7.2% 2020
Arsenic Cancer incidence rate 482.5% 448.6% 2022
Arsenic Cancer prevalence 6.0% 7.0% 2020
Arsenic Kidney disease rate 2.7% 3.0% 2020

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