Data & Methodology — Lehigh County

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

Contaminant Data — All Analytes

328 well testing events on record, covering 20 analytes. Data spans 1925 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. PA Avg
Iron 124 1925–2023 98%
30% of limit ↓ 95% below
Radon 8 1999–2023 100%
61% of limit ↓ 53% below
PFOA municipal 434 2023–2025 45%
110% of limit ~ typical
PFOS municipal 435 2023–2025 37%
122% of limit ~ typical
Manganese 93 1965–2023 95%
0% of limit ↓ 100% below
Nitrate 170 1925–2023 99%
23% of limit ↑ 28% above
PFHxS municipal 118 2023–2025 8%
38% of limit ~ typical
PFNA municipal 118 2023–2025 5%
80% of limit ~ typical
Sulfate 129 1925–2023 100%
13% of limit ↓ 23% below
Arsenic 12 1975–2023 75%
6% of limit ↓ 79% below
Chloride 155 1925–2023 100%
3% of limit ↓ 74% below
Fluoride 94 1965–2023 96%
0% of limit ↓ 100% below
HFPO-DA (GenX) municipal 425 2023–2025 0%
— —
Lead 10 1973–2023 20%
2% of limit ↓ 56% below
Nitrite 24 1973–2023 21%
1% of limit ↓ 33% below
Uranium 6 1985–2023 67%
6% of limit ↑ 148% above
Hardness 130 1925–2023 100%
— ~ typical
PFBS municipal 425 2023–2025 38%
— ↓ 26% below
pH 171 1951–2023 100%
— ~ typical
Sodium 97 1925–2023 100%
— ↓ 69% 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 Lehigh County

Of the 155 chloride tests on record for Lehigh County (1925–2023), 0% found none, and half were below 7 mg/L.

Of the 94 fluoride tests on record for Lehigh County (1965–2023), 4% found none.

Of the 124 iron tests on record for Lehigh County (1925–2023), 2% found none, and half were below 80 µg/L.

Of the 93 manganese tests on record for Lehigh County (1965–2023), 5% found none.

Of the 170 nitrate tests on record for Lehigh County (1925–2023), 1% found none, and half were below 2.26 mg/L.

Of the 316 pfoa tests on record for Lehigh County (2025), 43% found none, and half were below 2.11 ng/L.

Of the 317 pfos tests on record for Lehigh County (2025), 54% found none.

Of the 129 sulfate tests on record for Lehigh County (1925–2023), 0% found none, and half were below 33 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 124 samples
  • PFOA 434 samples
  • PFOS 435 samples
  • Manganese 93 samples
  • Nitrate 170 samples
  • Sulfate 129 samples
  • Chloride 155 samples
  • Fluoride 94 samples
  • HFPO-DA (GenX) 425 samples
  • Nitrite 24 samples
  • Hardness 130 samples
  • PFBS 425 samples
  • pH 171 samples
  • Sodium 97 samples

Limited data (<15 samples) — interpret with caution

  • Radon 8 samples
  • Arsenic 12 samples
  • Lead 10 samples
  • Uranium 6 samples

Public vs. Private Water in Lehigh County

203 Active public water systems
294,956 Residents on public water
17% Households on private wells

Public water systems in Lehigh 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 Lehigh 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 Lehigh County Prevalence PA Average Source Year
Nitrate Cancer prevalence 6.7% 7.0% 2020

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