Well Water Nerd

Well water in York County, Maine

In York County, 23% of 2,174 private wells tested had arsenic above the Maine guideline (10 ug/L), according to Maine CDC.

2,695 private wells tested in state summaries; 386 individual samples from 386 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, 9% of 386 PFOA results in York County were above the EPA limit of 4 ng/L. In that targeted sampling, 6% of 386 PFOS results in York 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.

ContaminantWells testedAbove state levelMedian95th pctHighestState level
Arsenic2,17423%10 ug/L
Manganese1,9685%300 ug/L
Fluoride2,6953%2 mg/L
Uranium1,8352%30 ug/L
Nitrate2,517<1%10 mg/L
Nitrite2,518<1%1 mg/L

What individual samples found

Each row summarizes every public sample for that contaminant inside York 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.

ContaminantSamplesDetectedAbove limitMedianHighestLimit
Arsenic
1997 to 2019
4898%69%55.571010 ug/L
EPA limit
PFOA
2017 to 2026
38658%9%0.3471104 ng/L
EPA limit
Nitrate
1953 to 2019
9472%9%0.0732910 mg/L
EPA limit
PFOS
2017 to 2026
38648%6%030.64 ng/L
EPA limit
PFHxS
2017 to 2026
38536%1%031.210 ng/L
EPA limit
PFNA
2017 to 2026
3856%<1%011.610 ng/L
EPA limit
Uranium
1999 to 2019
2463%0%0.12921.830 ug/L
EPA limit
Radium (226 + 228)
1975 to 2019
1995%0%025 pCi/L
EPA limit
Copper
1999 to 2019
1850%0%00.031.3 mg/L
EPA limit
E. coli
2011 to 2019
140%0%000 MPN/100mL
EPA limit
Chloride
1953 to 2019
9099%no limit9.4870250 mg/L
nuisance level
Iron
1961 to 2007
10100%no limit25069,900300 ug/L
nuisance level

Sampled fewer than 10 times, too few to summarize: Fluoride (4), Lead (3), Sodium (9), Manganese (8), Radon (8).

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What this means

Among homeowners in York County who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (23% of 2,174 wells), fluoride (3% of 2,695 wells), and uranium (2% of 1,835 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 York County

  • Volatile organic compounds (VOCs)111 leaking underground storage tank sites on record locally.
  • PFAS49 unlined landfills on record locally.
  • Metals panel91 hazardous waste sites on record locally.
  • PFOA9% of 386 local samples were above the limit.
  • PFOS6% of 386 local samples were above the limit.
  • Manganese5% of 1,968 local wells tested were above the Maine guideline.
  • Fluoride3% of 2,695 local wells tested were above the Maine guideline.
  • Uranium2% of 1,835 local wells tested were above the Maine guideline.
  • PFHxS1% of 385 local samples were above the limit.
  • PFNA<1% of 385 local samples were above the limit.
  • Nitrite<1% of 2,518 local wells tested were above the Maine guideline.

Wells in York County

11,937 domestic wells in York County are on record with the state since 1970. 98% are drilled into bedrock, and the typical well is 290 feet deep (one in ten goes past 500 feet).

In a typical York County well, bedrock starts about 18 feet down, the median yield is 8 gallons per minute, 19% 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.

287
1970s
710
1980s
2,439
1990s
2,712
2000s
2,178
2010s
3,231
2020s

Contamination sources on record in York County

Maine DEP records 111 leaking underground storage tank sites, 49 unlined landfills, and 91 hazardous waste sites in York County, among 494 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.

111
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.
91
hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
243
other remediation projects

Treatment that fits the local profile

Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
PFOA
Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
PFOS
Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
PFHxS
Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

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Common questions

How deep are wells in York County?

The typical domestic well in York County is 290 feet deep, based on 11,937 wells reported to the state since 1970. One in ten is deeper than 500 feet. 98% are drilled into bedrock.

Is there arsenic in well water in York County?

Arsenic was detected in 98% of 48 public well samples in York County, and 69% 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 York County?

The median radon level across 8 public samples in York County was 2,290 pCi/L, with a high of 12,800 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in York 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 York County

3 towns have fewer than 30 public samples and are included in the York County totals above rather than shown separately: Cornish, Ogunquit, Old Orchard Beach.

Sources

  • Maine DEP PFAS investigation: 1,540 samples in York County. PFAS results for private wells sampled by the Maine Department of Environmental Protection. Retrieved September 3, 2026.
  • USGS Water Quality Portal: 351 samples in York 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 York County, up to 2,695 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: 12,466 well records in York County, 11,937 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: 494 regulated sites located in York 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.