Well water in Penobscot, Maine
In Penobscot, 24% of 70 private wells tested had arsenic above the Maine guideline (10 ug/L), according to Maine CDC.
73 private wells tested in state summaries; 3 individual samples from 2 wells, 2002 to 2024. 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.
Get the free Penobscot well report
One email with the numbers above, what they mean for a home in Penobscot, exactly which tests to order, and what treatment fits the local profile. No spam, unsubscribe in one click.
What this means
Among homeowners in Penobscot who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (24% of 70 wells), uranium (9% of 64 wells), and fluoride (7% of 70 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 Penobscot
- Volatile organic compounds (VOCs)3 leaking underground storage tank sites on record locally.
- PFAS1 unlined landfill on record locally.
- Arsenic24% of 70 local wells tested were above the Maine guideline.
- Uranium9% of 64 local wells tested were above the Maine guideline.
- Fluoride7% of 70 local wells tested were above the Maine guideline.
- Manganese3% of 65 local wells tested were above the Maine guideline.
- Coliform bacteriaRecommended for every private well, every year.
- NitrateRecommended for every private well, especially near farms or septic systems.
Wells in Penobscot
252 domestic wells in Penobscot are on record with the state since 1971. 100% are drilled into bedrock, and the typical well is 180 feet deep (one in ten goes past 345 feet).
In a typical Penobscot well, bedrock starts about 20 feet down, the median yield is 6 gallons per minute, 20% 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 Penobscot
Maine DEP records 3 leaking underground storage tank sites and 1 unlined landfill in Penobscot, among 6 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.
- 3
- 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.
- 2
- other remediation projects
Treatment that fits the local profile
- Arsenic
- Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
- Uranium
- Point-of-use reverse osmosis; Anion exchange; Whole-house anion exchange
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
Book a free water test in Penobscot
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation.
Common questions
How deep are wells in Penobscot?
The typical domestic well in Penobscot is 180 feet deep, based on 252 wells reported to the state since 1971. One in ten is deeper than 345 feet. 100% are drilled into bedrock.
Is there arsenic in well water in Penobscot?
Arsenic was detected in 100% of 3 public well samples in Penobscot, and 100% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How often should I test a private well in Penobscot?
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: 8 samples in Penobscot. PFAS results for private wells sampled by the Maine Department of Environmental Protection. Retrieved September 3, 2026.
- USGS Water Quality Portal: 5 samples in Penobscot. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- Maine Tracking Network private well summaries: summaries for 6 contaminants in Penobscot, up to 73 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: 257 well records in Penobscot, 252 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: 6 regulated sites located in Penobscot. 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.