Data & Methodology — Chittenden County

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

Contaminant Data — All Analytes

47 well testing events on record, covering 20 analytes. Data spans 1952 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. VT Avg
Radon 438 — 100%
183% of limit ↓ 59% below
Manganese 2454 1980–2003 100%
10% of limit ↓ 98% below
Iron 2235 1980–2003 100%
17% of limit ↓ 92% below
Arsenic 4485 2003 79%
20% of limit ↓ 61% below
Uranium 4238 2003 100%
7% of limit ~ typical
Chloride 3961 1980 100%
1% of limit ↓ 88% below
Lead 11370 2003 99%
13% of limit ↓ 81% below
Nitrate 4814 — 100%
2% of limit ↓ 24% below
Fluoride 5063 1980 100%
4% of limit ~ typical
HFPO-DA (GenX) municipal 40 2023–2025 0%
— —
Nitrite 4755 — 100%
2% of limit ~ typical
PFHxS municipal 40 2023–2025 0%
— —
PFNA municipal 40 2023–2025 0%
— —
PFOA municipal 40 2023–2025 0%
— —
PFOS municipal 40 2023–2025 0%
— —
Sulfate 440 1980 100%
7% of limit ~ typical
Sodium 2223 1980–2003 100%
— ↓ 28% below
pH 1550 1980–2003 100%
— ~ typical
PFBS municipal 40 2023–2025 0%
— —
Hardness 1796 1980–2003 100%
— ↑ 89% 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 Chittenden County

Of the 4485 arsenic tests on record for Chittenden County (2003), 21% found none, and half were below 2 µg/L.

Of the 3961 chloride tests on record for Chittenden County (1980), 0% found none, and half were below 2.6 mg/L.

Of the 5063 fluoride tests on record for Chittenden County (1980), 0% found none, and half were below 150 µg/L.

Of the 2235 iron tests on record for Chittenden County (1980–2003), 0% found none, and half were below 50 µg/L.

Of the 11370 lead tests on record for Chittenden County (2003), 1% found none, and half were below 2 µg/L.

Of the 2454 manganese tests on record for Chittenden County (1980–2003), 0% found none, and half were below 5 µg/L.

Of the 4814 nitrate tests on record for Chittenden County, 0% found none, and half were below 250 µg/L.

Of the 440 sulfate tests on record for Chittenden County (1980), 0% found none, and half were below 17 mg/L.

Of the 4238 uranium tests on record for Chittenden County (2003), 0% found none, and half were below 2 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Radon 438 samples
  • Manganese 2454 samples
  • Iron 2235 samples
  • Arsenic 4485 samples
  • Uranium 4238 samples
  • Chloride 3961 samples
  • Lead 11370 samples
  • Nitrate 4814 samples
  • Fluoride 5063 samples
  • Nitrite 4755 samples
  • Sulfate 440 samples
  • Sodium 2223 samples
  • pH 1550 samples
  • Hardness 1796 samples

No private-well PFAS data for Chittenden County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Chittenden 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 Chittenden County

96 Active public water systems
150,374 Residents on public water
19% Households on private wells

Public water systems in Chittenden 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 Chittenden 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 Chittenden County Prevalence VT Average Source Year
Arsenic Cancer prevalence 6.3% 7.0% 2020
Arsenic Kidney disease rate 2.3% 2.8% 2020
Lead Heart disease rate 4.8% 6.3% 2020

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