Well water in Cumberland County, Maine
In Cumberland County, 20% of 3,441 private wells tested had uranium above the Maine guideline (30 ug/L), according to Maine CDC.
4,655 private wells tested in state summaries; 574 individual samples from 574 wells, 1958 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 574 PFOA results in Cumberland County were above the EPA limit of 4 ng/L. In that targeted sampling, 9% of 574 PFOS results in Cumberland 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 Cumberland 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 | |
|---|---|---|---|---|---|---|---|
| Arsenic 1999 to 2019 | 73 | 71% | 52% | 24 | 450 | 10 ug/L EPA limit | |
| Uranium 1958 to 2019 | 32 | 78% | 25% | 2.57 | 960 | 30 ug/L EPA limit | |
| Nitrate 1958 to 2019 | 508 | 89% | 18% | 1.55 | 162 | 10 mg/L EPA limit | |
| PFOA 2019 to 2026 | 574 | 61% | 12% | 0.447 | 121 | 4 ng/L EPA limit | |
| PFOS 2019 to 2026 | 574 | 51% | 9% | 0.485 | 91.8 | 4 ng/L EPA limit | |
| Radium (226 + 228) 1958 to 2019 | 20 | 90% | 5% | 0 | 57 | 5 pCi/L EPA limit | |
| Fluoride 1958 to 2019 | 25 | 80% | 4% | 0.03 | 4.9 | 4 mg/L EPA limit | |
| PFHxS 2020 to 2026 | 573 | 43% | <1% | 0 | 24 | 10 ng/L EPA limit | |
| PFNA 2020 to 2026 | 573 | 9% | 0% | 0 | 7.69 | 10 ng/L EPA limit | |
| Copper 1999 to 2019 | 13 | 85% | 0% | 0.001 | 0.012 | 1.3 mg/L EPA limit | |
| Chloride 1958 to 2019 | 380 | 100% | no limit | 29.1 | 2,020 | 250 mg/L nuisance level | |
| Sodium 1958 to 2015 | 29 | 100% | no limit | 15 | 814 | 20 mg/L health guideline | |
| Manganese 1975 to 2011 | 11 | 82% | no limit | 20 | 5,200 | 300 ug/L health guideline | |
| Iron 1974 to 2006 | 10 | 90% | no limit | 7 | 130 | 300 ug/L nuisance level |
Sampled fewer than 10 times, too few to summarize: Lead (8), E. coli (8), Radon (5).
Get the free Cumberland County well report
One email with the numbers above, what they mean for a home in Cumberland County, exactly which tests to order, and what treatment fits the local profile. No spam, unsubscribe in one click.
What this means
Among homeowners in Cumberland County who sent a sample to the state lab, the health-based limits most often exceeded were uranium (20% of 3,441 wells), arsenic (17% of 4,050 wells), and fluoride (2% of 4,655 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 Cumberland County
- Volatile organic compounds (VOCs)136 leaking underground storage tank sites on record locally.
- PFAS50 unlined landfills on record locally.
- Metals panel113 hazardous waste sites on record locally.
- PFOA12% of 574 local samples were above the limit.
- PFOS9% of 574 local samples were above the limit.
- Radium (226 + 228)5% of 20 local samples were above the limit.
- Manganese5% of 3,513 local wells tested were above the Maine guideline.
Wells in Cumberland County
13,047 domestic wells in Cumberland County are on record with the state since 1970. 97% are drilled into bedrock, and the typical well is 280 feet deep (one in ten goes past 510 feet).
In a typical Cumberland County well, bedrock starts about 16 feet down, the median yield is 6 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 Cumberland County
Maine DEP records 136 leaking underground storage tank sites, 50 unlined landfills, and 113 hazardous waste sites in Cumberland County, among 869 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.
- 136
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 50
- unlined landfillsOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 113
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 570
- other remediation projects
Treatment that fits the local profile
- Uranium
- Point-of-use reverse osmosis; Anion exchange; Whole-house anion exchange
- Arsenic
- Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- 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
Book a free water test in Cumberland County
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 Cumberland County?
The typical domestic well in Cumberland County is 280 feet deep, based on 13,047 wells reported to the state since 1970. One in ten is deeper than 510 feet. 97% are drilled into bedrock.
Is there arsenic in well water in Cumberland County?
Arsenic was detected in 71% of 73 public well samples in Cumberland County, and 52% 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 Cumberland County?
The median radon level across 5 public samples in Cumberland County was 8,590 pCi/L, with a high of 45,300 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Cumberland 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 Cumberland County
- Baldwin16% uranium
- Bridgton28% uranium
- Brunswick9% arsenic
- Casco44% uranium
- Cumberland30% uranium
- Falmouth27% uranium
- Freeport5% uranium
- Gorham49% arsenic
- Gray34% uranium
- Harpswell3% arsenic
- Harrison17% uranium
- Naples56% uranium
- New Gloucester34% uranium
- North Yarmouth24% uranium
- Portland11% arsenic
- Pownal12% uranium
- Raymond43% uranium
- Scarborough32% arsenic
- Sebago45% uranium
- Standish28% arsenic
- Windham20% arsenic
- Yarmouth18% arsenic
6 towns have fewer than 30 public samples and are included in the Cumberland County totals above rather than shown separately: Cape Elizabeth, Chebeague Island, Frye Island, Long Island, South Portland, Westbrook.
Sources
- Maine DEP PFAS investigation: 2,292 samples in Cumberland County. PFAS results for private wells sampled by the Maine Department of Environmental Protection. Retrieved September 3, 2026.
- USGS Water Quality Portal: 1,124 samples in Cumberland 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 Cumberland County, up to 4,655 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: 13,593 well records in Cumberland County, 13,047 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: 869 regulated sites located in Cumberland 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.