Well water in Thetford, Vermont
In Thetford, 10% of 193 private wells tested had arsenic above the Vermont limit (10 ug/L), according to the Vermont Department of Health.
193 private wells tested in state summaries; 7 individual samples from 4 wells, 1967 to 1994. Data refreshed September 3, 2026.
What homeowner tests found
Vermont Tracking private well summaries: private wells tested and reported to the state. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA.
| Contaminant | Wells tested | Above state level | Median | 95th pct | Highest | State level | |
|---|---|---|---|---|---|---|---|
| Arsenic | 193 | 10% | * | 20 | 66 | 10 ug/L | |
| Gross alpha Gross Alpha | 109 | <1% | 2.1 | 10.1 | 16.7 | 15 pCi/L | |
| Fluoride | 179 | 0% | 0.05 | 0.198 | 0.94 | 4 mg/L | |
| Uranium | 174 | 0% | 1 | 8 | 13 | 20 ug/L | |
| Nitrate | 115 | 0% | 0.25 | 5.8 | 8.07 | 10 mg/L |
* suppressed by the publisher because too few wells were tested.
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What this means
Among homeowners in Thetford who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (10% of 193 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.
What to test for in Thetford
- Volatile organic compounds (VOCs)14 leaking underground storage tank sites on record locally.
- PFAS1 unlined landfill on record locally.
- Metals panel6 hazardous waste sites on record locally.
- Arsenic10% of 193 local wells tested were above the Vermont limit.
- Gross alpha<1% of 109 local wells tested were above the Vermont limit.
- Coliform bacteriaRecommended for every private well, every year.
- NitrateAbove the limit in 3 of 7 local samples; too few to quote a rate.
- ManganeseDetected in 100% of local samples.
- ChlorideDetected in 100% of local samples.
- IronDetected in 75% of local samples.
Wells in Thetford
368 domestic wells in Thetford are on record with the state since 1995. 98% are drilled into bedrock, and the typical well is 323 feet deep (one in ten goes past 522 feet).
In a typical Thetford well, bedrock starts about 23 feet down, the median yield is 6 gallons per minute, 29% of wells yield under 3 gallons per minute and usually need a storage tank.
Bedrock wells are where arsenic, uranium and radon come from: the water sits in fractures in granite and metamorphic rock and picks up whatever the rock carries. That is why testing for those three matters more here than in a dug or gravel well.
Contamination sources on record in Thetford
Vermont ANR records 14 leaking underground storage tank sites, 1 unlined landfill, and 6 hazardous waste sites in Thetford, among 26 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 14
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 1
- unlined landfillOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 6
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 5
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
Treatment that fits the local profile
- Arsenic
- Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
- Manganese
- Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
- Chloride
- Point-of-use reverse osmosis; Distillation
Book a free water test in Thetford
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Common questions
How deep are wells in Thetford?
The typical domestic well in Thetford is 323 feet deep, based on 368 wells reported to the state since 1995. One in ten is deeper than 522 feet. 98% are drilled into bedrock.
How often should I test a private well in Thetford?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Sources
- USGS Water Quality Portal: 27 samples in Thetford. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- Vermont Tracking private well summaries: summaries for 5 contaminants in Thetford, up to 193 wells each. Town summaries of private well tests reported to the Vermont Department of Health, published through Vermont Environmental Public Health Tracking. Shares are against the limit Vermont applies to each analyte: arsenic 10 ug/L, uranium 20 ug/L (stricter than EPA), fluoride 4 mg/L, nitrate 10 mg/L, gross alpha 15 pCi/L, radon 4,000 pCi/L advisory. Only towns with 20 or more results are published; statistics below the reporting limit show as *. Retrieved September 3, 2026.
- Vermont ANR well completion reports: 398 well records in Thetford, 368 domestic. Well completion reports filed with the Vermont Agency of Natural Resources since 1966. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 3, 2026.
- Vermont ANR regulated sites: 26 regulated sites located in Thetford. Hazardous waste sites, landfills and underground storage tanks from the Vermont Agency of Natural Resources. Retrieved September 3, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.