Well water in Jefferson, Maine
In Jefferson, 10% of 208 private wells tested had arsenic above the Maine guideline (10 ug/L), according to Maine CDC.
229 private wells tested in state summaries; 8 individual samples from 8 wells, 2023 to 2025. Data refreshed September 3, 2026.
Maine DEP samples private wells near fields where sludge or septage was spread and near other known PFAS sources, and resamples detections. PFAS shares describe wells that were tested for a reason, not every well in the area.
What homeowner tests found
Maine Tracking Network 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.
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What this means
Among homeowners in Jefferson who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (10% of 208 wells), fluoride (5% of 217 wells), and uranium (4% of 163 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 Jefferson
- PFAS1 unlined landfill on record locally.
- Volatile organic compounds (VOCs)1 unlined landfill on record locally.
- Arsenic10% of 208 local wells tested were above the Maine guideline.
- Fluoride5% of 217 local wells tested were above the Maine guideline.
- Uranium4% of 163 local wells tested were above the Maine guideline.
- Manganese4% of 195 local wells tested were above the Maine guideline.
- Nitrate<1% of 229 local wells tested were above the Maine guideline.
- Coliform bacteriaRecommended for every private well, every year.
Wells in Jefferson
543 domestic wells in Jefferson are on record with the state since 1970. 98% are drilled into bedrock, and the typical well is 240 feet deep (one in ten goes past 400 feet).
In a typical Jefferson well, bedrock starts about 17 feet down, the median yield is 5 gallons per minute, 25% 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 Jefferson
Maine DEP records 1 unlined landfill in Jefferson, among 2 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.
- 1
- unlined landfillOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 1
- other remediation project
Treatment that fits the local profile
- Arsenic
- Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
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Common questions
How deep are wells in Jefferson?
The typical domestic well in Jefferson is 240 feet deep, based on 543 wells reported to the state since 1970. One in ten is deeper than 400 feet. 98% are drilled into bedrock.
How often should I test a private well in Jefferson?
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
- Maine DEP PFAS investigation: 32 samples in Jefferson. PFAS results for private wells sampled by the Maine Department of Environmental Protection. Retrieved September 3, 2026.
- Maine Tracking Network private well summaries: summaries for 6 contaminants in Jefferson, up to 229 wells each. Town summaries of private well tests run by the Maine Health and Environmental Testing Laboratory, published by Maine CDC through the Maine Tracking Network. Shares are against Maine's guideline for each analyte (arsenic 10 ug/L, uranium 30 ug/L, fluoride 2 mg/L, manganese 0.3 mg/L, nitrate 10 mg/L, nitrite 1 mg/L). Towns with too few tests are suppressed (NR). Only the share above the guideline and wells tested are published; no medians. Retrieved September 3, 2026.
- Maine Geological Survey well database: 556 well records in Jefferson, 543 domestic. Well construction records reported to the Maine Geological Survey by licensed well drillers. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 3, 2026.
- Maine DEP regulated sites: 2 regulated sites located in Jefferson. Remediation sites, leaking underground storage tanks and closed municipal landfills from the Maine Department of Environmental Protection. 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.