Well water in Southwest Harbor, Maine
In Southwest Harbor, none of 30 private wells tested had nitrate above the Maine guideline (10 mg/L), according to Maine CDC.
The strongest signal is fluoride: 4% of 26 local wells tested were above the Maine guideline, too few samples to carry the headline but first on the test list below.
30 private wells tested in state summaries; 54 test results across 9 contaminants from at least 3 wells, 1985 to 2004; arsenic has the most at 11. Data refreshed September 3, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
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.
What individual samples found
Each row summarizes every public sample for that contaminant inside Southwest Harbor. 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 | Above limit | Samples | Detected | Median | Highest | Limit |
|---|---|---|---|---|---|---|
| Arsenic 2003 to 2004 | 11 | 27% | 0 | 0.6 | 10 ug/L EPA limit |
Sampled fewer than 10 times, too few to summarize: Fluoride (7), Nitrate (7), Copper (4), Uranium (4), Lead (4), Chloride (7), Iron (5), Manganese (5).
Closer than the town
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
Among homeowners in Southwest Harbor who sent a sample to the state lab, the health-based limits most often exceeded were fluoride (4% of 26 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 Southwest Harbor
- 1Fluoride4% of 26 local wells tested were above the Maine guideline.
- 2Coliform bacteriaRecommended for every private well, every year.
- 3NitrateRecommended for every private well, especially near farms or septic systems.
- 4Manganese8% of 24 local wells tested were above the Maine guideline.
- 5ChlorideDetected in 100% of local samples.
- 6IronDetected in 100% of local samples.
- 7CopperDetected in 75% of local samples.
- 8Volatile organic compounds (VOCs)2 leaking underground storage tank sites on record locally.
- 9Metals panel3 hazardous waste sites on record locally.
Test your Southwest Harbor well for fluoride, coliform bacteria and nitrate
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.
Where to get a well tested in Maine: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Southwest Harbor numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Southwest Harbor
136 domestic wells in Southwest Harbor are on record with the state since 1970. 99% are drilled into bedrock, and the typical well is 218 feet deep (one in ten goes past 400 feet).
In a typical Southwest Harbor well, bedrock starts about 7 feet down, the median yield is 8 gallons per minute, 18% 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.
The rock under Southwest Harbor
Not a principal aquifer
The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.
Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the town centroid. A single well can sit in a different unit, especially near a boundary.
Official help in Maine
Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.
- Private Well Water, Maine CDC
- Laboratory Accreditation, Maine CDC
Contamination sources on record in Southwest Harbor
Maine DEP records 2 leaking underground storage tank sites and 3 hazardous waste sites in Southwest Harbor, among 10 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.
- 2
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 3
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 5
- other remediation projects
Treatment that fits the local profile
Manganese
Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Iron
Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
Systems we would look at first
Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For manganese
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
Free, no obligation
Get on the list for a free in-home water test in Southwest Harbor
No water treatment company serves Southwest Harbor through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Southwest Harbor, and you get an email naming it first.
Common questions
How deep are wells in Southwest Harbor?
The typical domestic well in Southwest Harbor is 218 feet deep, based on 136 wells reported to the state since 1970. One in ten is deeper than 400 feet. 99% are drilled into bedrock.
Is there arsenic in well water in Southwest Harbor?
Arsenic was detected in 27% of 11 public well samples in Southwest Harbor, 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 often should I test a private well in Southwest Harbor?
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 near Southwest Harbor
Closest first. Groundwater does not stop at a line on a map, so the next town over is a fair second opinion.
Want the numbers themselves? Download the Maine dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 54 samples in Southwest Harbor. 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 Southwest Harbor, up to 30 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: 151 well records in Southwest Harbor, 136 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: 10 regulated sites located in Southwest Harbor. 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.