Data & Methodology — Adams County

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

Contaminant Data — All Analytes

374 well testing events on record, covering 22 analytes. Data spans 1925 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. PA Avg
Radon 12 1993–2021 100%
95% of limit ↓ 27% below
PFOS municipal 321 2023–2025 36%
121% of limit ~ typical
Iron 92 1925–2023 87%
33% of limit ↓ 94% below
Nitrate 191 1925–2023 97%
32% of limit ↑ 81% above
Manganese 85 1960–2023 78%
20% of limit ↓ 96% below
PFOA municipal 321 2023–2025 28%
98% of limit ~ typical
Sulfate 79 1925–2023 97%
10% of limit ↓ 42% below
Arsenic 46 1975–2023 76%
20% of limit ↓ 33% below
Lead 51 1969–2023 12%
3% of limit ↓ 37% below
Fluoride 66 1960–2023 68%
2% of limit ↓ 44% below
Nitrite 166 1973–2023 24%
3% of limit ↑ 100% above
Chloride 110 1925–2023 100%
3% of limit ↓ 73% below
HFPO-DA (GenX) municipal 320 2023–2025 0%
— —
PFHxS municipal 38 2023–2025 5%
48% of limit ~ typical
PFNA municipal 38 2023–2025 0%
— —
Uranium 17 1993–2021 71%
6% of limit ↑ 142% above
pH 191 1960–2023 100%
— ~ typical
PFBS municipal 320 2023–2025 28%
— ~ typical
Hardness 89 1925–2023 99%
— ~ typical
Total Coliform 5 1993–2021 61%
— ~ typical
Sodium 74 1925–2023 100%
— ↓ 45% below
E. coli 5 2003–2021 11%
— ~ 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 Adams County

Of the 46 arsenic tests on record for Adams County (1975–2023), 24% found none, and half were below 1.44 µg/L.

Of the 110 chloride tests on record for Adams County (1925–2023), 0% found none, and half were below 7.3 mg/L.

Of the 66 fluoride tests on record for Adams County (1960–2023), 32% found none, and half were below 40 µg/L.

Of the 92 iron tests on record for Adams County (1925–2023), 13% found none, and half were below 80 µg/L.

Of the 51 lead tests on record for Adams County (1969–2023), 88% found none.

Of the 85 manganese tests on record for Adams County (1960–2023), 22% found none, and half were below 7.45 µg/L.

Of the 191 nitrate tests on record for Adams County (1925–2023), 3% found none, and half were below 3.2 mg/L.

Of the 283 pfoa tests on record for Adams County (2025), 70% found none.

Of the 283 pfos tests on record for Adams County (2025), 63% found none.

Of the 79 sulfate tests on record for Adams County (1925–2023), 3% found none, and half were below 25 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • PFOS 321 samples
  • Iron 92 samples
  • Nitrate 191 samples
  • Manganese 85 samples
  • PFOA 321 samples
  • Sulfate 79 samples
  • Arsenic 46 samples
  • Lead 51 samples
  • Fluoride 66 samples
  • Nitrite 166 samples
  • Chloride 110 samples
  • HFPO-DA (GenX) 320 samples
  • Uranium 17 samples
  • pH 191 samples
  • PFBS 320 samples
  • Hardness 89 samples
  • Sodium 74 samples

Limited data (<15 samples) — interpret with caution

  • Radon 12 samples
  • Total Coliform 5 samples
  • E. coli 5 samples

Public vs. Private Water in Adams County

165 Active public water systems
82,224 Residents on public water
53% Households on private wells

Public water systems in Adams 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 Adams 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 Adams County Prevalence PA Average Source Year
Arsenic Cancer prevalence 8.0% 7.0% 2020
Arsenic Kidney disease rate 2.5% 3.0% 2020
Lead Heart disease rate 5.8% 7.2% 2020

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