Well water in Portland, Maine
In Portland, 11% of 63 private wells tested had arsenic above the Maine guideline (10 ug/L), according to Maine CDC.
66 private wells tested in state summaries; 5 individual samples from 5 wells, 2023 to 2025. 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 Portland well report
One email with the numbers above, what they mean for a home in Portland, exactly which tests to order, and what treatment fits the local profile. No spam, unsubscribe in one click.
What this means
Among homeowners in Portland who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (11% of 63 wells) and uranium (2% of 48 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.
Manganese exceeds the state's advisory level in a sizable share of wells; this is mostly a taste, staining or diet issue rather than a toxicity one.
What to test for in Portland
- Volatile organic compounds (VOCs)25 leaking underground storage tank sites on record locally.
- PFAS4 unlined landfills on record locally.
- Metals panel26 hazardous waste sites on record locally.
- Manganese17% of 60 local wells tested were above the Maine guideline.
- Arsenic11% of 63 local wells tested were above the Maine guideline.
- Uranium2% of 48 local wells tested were above the Maine guideline.
- Coliform bacteriaRecommended for every private well, every year.
- PFOAAbove the limit in 1 of 5 local samples; too few to quote a rate.
- PFOSAbove the limit in 1 of 5 local samples; too few to quote a rate.
- NitrateRecommended for every private well, especially near farms or septic systems.
Wells in Portland
79 domestic wells in Portland are on record with the state since 1985. 100% are drilled into bedrock, and the typical well is 200 feet deep (one in ten goes past 344 feet).
In a typical Portland well, bedrock starts about 10 feet down, the median yield is 7 gallons per minute, 22% 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 Portland
Maine DEP records 25 leaking underground storage tank sites, 4 unlined landfills, and 26 hazardous waste sites in Portland, among 285 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.
- 25
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 4
- unlined landfillsOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 26
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 230
- 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
Book a free water test in Portland
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 Portland?
The typical domestic well in Portland is 200 feet deep, based on 79 wells reported to the state since 1985. One in ten is deeper than 344 feet. 100% are drilled into bedrock.
How often should I test a private well in Portland?
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: 20 samples in Portland. PFAS results for private wells sampled by the Maine Department of Environmental Protection. Retrieved September 3, 2026.
- Maine Tracking Network private well summaries: summaries for 6 contaminants in Portland, up to 66 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: 93 well records in Portland, 79 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: 285 regulated sites located in Portland. 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.