Data & Methodology — Addison County

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

Contaminant Data — All Analytes

13 well testing events on record, covering 20 analytes. Data spans 1953 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. VT Avg
Iron 866 1966–1980 100%
17% of limit ↓ 92% below
Manganese 982 1966–1980 100%
6% of limit ↓ 99% below
Lead 3297 — 99%
20% of limit ↓ 72% below
Chloride 1621 1966–1980 100%
1% of limit ↓ 84% below
Arsenic 1835 — 56%
20% of limit ↓ 61% below
Uranium 1733 — 99%
7% of limit ~ typical
Nitrate 2023 1966 100%
2% of limit ↓ 24% below
Fluoride 1835 1966–1980 100%
3% of limit ~ typical
HFPO-DA (GenX) municipal 14 2024–2025 0%
— —
Nitrite 1965 — 100%
2% of limit ~ typical
PFHxS municipal 14 2024–2025 0%
— —
PFNA municipal 14 2024–2025 0%
— —
PFOA municipal 14 2024–2025 0%
— —
PFOS municipal 14 2024–2025 0%
— —
Radon 22 — 100%
89% of limit ↓ 80% below
Sulfate 58 1966–1980 100%
5% of limit ~ typical
Sodium 860 1966–1980 100%
— ↓ 60% below
pH 549 1966–1980 100%
— ~ typical
PFBS municipal 14 2024–2025 0%
— —
Hardness 739 1966–1980 100%
— ↑ 124% above

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 VT.

Compare your result with Addison County

Of the 1835 arsenic tests on record for Addison County, 44% found none, and half were below 1 µg/L.

Of the 1621 chloride tests on record for Addison County (1966–1980), 0% found none, and half were below 3.35 mg/L.

Of the 1835 fluoride tests on record for Addison County (1966–1980), 0% found none, and half were below 130 µg/L.

Of the 866 iron tests on record for Addison County (1966–1980), 0% found none, and half were below 50 µg/L.

Of the 3297 lead tests on record for Addison County, 1% found none, and half were below 3 µg/L.

Of the 982 manganese tests on record for Addison County (1966–1980), 0% found none, and half were below 3 µg/L.

Of the 2023 nitrate tests on record for Addison County (1966), 0% found none, and half were below 250 µg/L.

Of the 58 sulfate tests on record for Addison County (1966–1980), 0% found none, and half were below 12.5 mg/L.

Of the 1733 uranium tests on record for Addison County, 1% found none, and half were below 2 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 866 samples
  • Manganese 982 samples
  • Lead 3297 samples
  • Chloride 1621 samples
  • Arsenic 1835 samples
  • Uranium 1733 samples
  • Nitrate 2023 samples
  • Fluoride 1835 samples
  • Nitrite 1965 samples
  • Radon 22 samples
  • Sulfate 58 samples
  • Sodium 860 samples
  • pH 549 samples
  • Hardness 739 samples

No private-well PFAS data for Addison County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Addison County. PFAS testing for private wells requires a dedicated lab panel (~$300–$500). If you are near a military base, airport, or industrial site, consider testing proactively. Learn more about PFAS →

Public vs. Private Water in Addison County

70 Active public water systems
32,655 Residents on public water
64% Households on private wells

Public water systems in Addison 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 Addison 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 Addison County Prevalence VT Average Source Year
Arsenic Cancer prevalence 7.5% 7.0% 2020
Arsenic Kidney disease rate 2.8% 2.8% 2020
Lead Heart disease rate 5.0% 6.3% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Addison 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 VT with at least one sample for that analyte.

Last updated: 2026-07-31

Full methodology →