Well water in Aroostook County, Maine
In Aroostook County, 4% of 1,087 private wells tested had nitrate above the Maine guideline (10 mg/L), according to Maine CDC.
1,089 private wells tested in state summaries; 113 individual samples from 113 wells, 1953 to 2026. 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, 12% of 113 PFOS results in Aroostook County were above the EPA limit of 4 ng/L. In that targeted sampling, 12% of 113 PFOA results in Aroostook 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 Aroostook 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 | |
|---|---|---|---|---|---|---|---|
| PFOS 2019 to 2026 | 113 | 35% | 12% | 0 | 32.5 | 4 ng/L EPA limit | |
| PFOA 2019 to 2026 | 113 | 36% | 12% | 0 | 44.8 | 4 ng/L EPA limit | |
| Nitrate 1953 to 1987 | 58 | 95% | 7% | 1.75 | 31 | 10 mg/L EPA limit | |
| PFHxS 2019 to 2026 | 113 | 23% | <1% | 0 | 10.4 | 10 ng/L EPA limit | |
| PFNA 2019 to 2026 | 113 | 9% | 0% | 0 | 2.51 | 10 ng/L EPA limit | |
| Fluoride 1956 to 1992 | 10 | 70% | 0% | 0.1 | 0.2 | 4 mg/L EPA limit | |
| Chloride 1953 to 1992 | 88 | 97% | no limit | 9.25 | 98 | 250 mg/L nuisance level |
Sampled fewer than 10 times, too few to summarize: Iron (8), Manganese (7), Sodium (4).
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What this means
Among homeowners in Aroostook County who sent a sample to the state lab, the health-based limits most often exceeded were nitrate (4% of 1,087 wells), arsenic (3% of 844 wells), and uranium (<1% of 772 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 Aroostook County
- Volatile organic compounds (VOCs)119 leaking underground storage tank sites on record locally.
- PFAS49 unlined landfills on record locally.
- Metals panel30 hazardous waste sites on record locally.
- PFOS12% of 113 local samples were above the limit.
- PFOA12% of 113 local samples were above the limit.
- Arsenic3% of 844 local wells tested were above the Maine guideline.
- Manganese2% of 860 local wells tested were above the Maine guideline.
- PFHxS<1% of 113 local samples were above the limit.
- Uranium<1% of 772 local wells tested were above the Maine guideline.
- Nitrite<1% of 1,089 local wells tested were above the Maine guideline.
- Coliform bacteriaRecommended for every private well, every year.
Wells in Aroostook County
2,396 domestic wells in Aroostook County are on record with the state since 1975. 96% are drilled into bedrock, and the typical well is 175 feet deep (one in ten goes past 300 feet).
In a typical Aroostook County well, bedrock starts about 12 feet down, the median yield is 12 gallons per minute, 5% 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 Aroostook County
Maine DEP records 119 leaking underground storage tank sites, 49 unlined landfills, and 30 hazardous waste sites in Aroostook County, among 427 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.
- 119
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 49
- unlined landfillsOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 30
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 229
- other remediation projects
Treatment that fits the local profile
- PFOS
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- PFOA
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- PFHxS
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
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Common questions
How deep are wells in Aroostook County?
The typical domestic well in Aroostook County is 175 feet deep, based on 2,396 wells reported to the state since 1975. One in ten is deeper than 300 feet. 96% are drilled into bedrock.
How often should I test a private well in Aroostook 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 Aroostook County
- Caribou8% nitrate
- Fort Fairfield15% nitrate
- Fort Kent2% arsenic
- Hodgdon0% nitrate
- Houlton7% nitrate
- Island Falls0% fluoride
- Madawaska0% arsenic
- Mapleton7% nitrate
- Presque Isle2% arsenic
- Woodland3% nitrate
61 towns have fewer than 30 public samples and are included in the Aroostook County totals above rather than shown separately: Allagash, Amity, Ashland, Bancroft UT, Blaine, Bridgewater, Castle Hill, Caswell, Central Aroostook UT, Chapman, Connor UT, Crystal, Cyr plantation, Dyer Brook, Eagle Lake, Easton, Frenchville, Garfield plantation, Glenwood plantation, Grand Isle, Hamlin, Hammond, Haynesville, Hersey, Limestone, Linneus, Littleton, Ludlow, Macwahoc plantation, Mars Hill, Masardis, Merrill, Monticello, Moro plantation, Nashville plantation, New Canada, New Limerick, New Sweden, Northwest Aroostook UT, Oakfield, Orient, Penobscot Indian Island Reservation, Perham, Portage Lake, Reed plantation, Sherman, Smyrna, South Aroostook UT, Square Lake UT, St. Agatha, St. Francis, St. John plantation, Stockholm, Van Buren, Wade, Wallagrass, Washburn, Westfield, Westmanland, Weston, Winterville plantation.
Sources
- Maine DEP PFAS investigation: 452 samples in Aroostook County. PFAS results for private wells sampled by the Maine Department of Environmental Protection. Retrieved September 3, 2026.
- USGS Water Quality Portal: 175 samples in Aroostook 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 Aroostook County, up to 1,089 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: 3,445 well records in Aroostook County, 2,396 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: 427 regulated sites located in Aroostook 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.