Well water in Piscataquis County, Maine
In Piscataquis County, 12% of 320 private wells tested had arsenic above the Maine guideline (10 ug/L), according to Maine CDC.
384 private wells tested in state summaries; 30 individual samples from 30 wells, 1990 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. In that targeted sampling, 10% of 30 PFOA results in Piscataquis County were above the EPA limit of 4 ng/L. In that targeted sampling, 3% of 30 PFOS results in Piscataquis County were above the EPA limit of 4 ng/L.
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. County and state figures combine the town summaries, weighted by wells tested; medians are not combined.
What individual samples found
Each row summarizes every public sample for that contaminant inside Piscataquis County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Samples | Detected | Above limit | Median | Highest | Limit | |
|---|---|---|---|---|---|---|---|
| PFOA 2019 to 2024 | 30 | 40% | 10% | 0 | 9.08 | 4 ng/L EPA limit | |
| PFOS 2019 to 2024 | 30 | 23% | 3% | 0 | 4.84 | 4 ng/L EPA limit | |
| PFHxS 2019 to 2024 | 30 | 13% | 0% | 0 | 3.23 | 10 ng/L EPA limit | |
| PFNA 2019 to 2024 | 30 | 7% | 0% | 0 | 0.508 | 10 ng/L EPA limit | |
| Chloride 1990 to 2014 | 14 | 100% | no limit | 1.6 | 58 | 250 mg/L nuisance level |
Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (2), Nitrate (2), Arsenic (1), Uranium (1), Fluoride (1), Copper (1), E. coli (1), Sodium (2), Iron (1), Radon (1), Manganese (1).
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What this means
Among homeowners in Piscataquis County who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (12% of 320 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 Piscataquis County
- Volatile organic compounds (VOCs)14 leaking underground storage tank sites on record locally.
- PFAS21 unlined landfills on record locally.
- Metals panel10 hazardous waste sites on record locally.
- Arsenic12% of 320 local wells tested were above the Maine guideline.
- PFOA10% of 30 local samples were above the limit.
- Manganese5% of 307 local wells tested were above the Maine guideline.
- PFOS3% of 30 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 650 pCi/L.
- CopperDetected in 100% of local samples.
- ChlorideDetected in 100% of local samples.
Wells in Piscataquis County
1,608 domestic wells in Piscataquis County are on record with the state since 1970. 99% are drilled into bedrock, and the typical well is 200 feet deep (one in ten goes past 340 feet).
In a typical Piscataquis County well, bedrock starts about 20 feet down, the median yield is 8 gallons per minute, 11% 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 Piscataquis County
Maine DEP records 14 leaking underground storage tank sites, 21 unlined landfills, and 10 hazardous waste sites in Piscataquis County, among 108 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.
- 21
- unlined landfillsOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 10
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 63
- other remediation projects
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
- PFOA
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- PFOS
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- Copper
- Neutralizing filter to raise pH; Point-of-use reverse osmosis
- Chloride
- Point-of-use reverse osmosis; Distillation
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Common questions
How deep are wells in Piscataquis County?
The typical domestic well in Piscataquis County is 200 feet deep, based on 1,608 wells reported to the state since 1970. One in ten is deeper than 340 feet. 99% are drilled into bedrock.
Is there arsenic in well water in Piscataquis County?
Arsenic was detected in 100% of 1 public well samples in Piscataquis County, and 0% 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 high is radon in well water in Piscataquis County?
The median radon level across 1 public samples in Piscataquis County was 650 pCi/L, with a high of 650 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Piscataquis County?
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.
Towns in Piscataquis County
- Dover-Foxcroft14% arsenic
- Greenville7% arsenic
- Guilford3% arsenic
- Sebec10% arsenic
18 towns have fewer than 30 public samples and are included in the Piscataquis County totals above rather than shown separately: Abbot, Beaver Cove, Blanchard UT, Bowerbank, Brownville, Kingsbury plantation, Lake View plantation, Medford, Milo, Monson, Northeast Piscataquis UT, Northwest Piscataquis UT, Parkman, Sangerville, Shirley, Southeast Piscataquis UT, Wellington, Willimantic.
Sources
- Maine DEP PFAS investigation: 120 samples in Piscataquis County. PFAS results for private wells sampled by the Maine Department of Environmental Protection. Retrieved September 3, 2026.
- USGS Water Quality Portal: 28 samples in Piscataquis County. 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 Piscataquis County, up to 384 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: 1,653 well records in Piscataquis County, 1,608 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: 108 regulated sites located in Piscataquis County. 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.