Quick answer
About 510,000 people in Maine (38.4% of residents) got their water from private wells in 2010, according to USGS estimates. Maine Center for Disease Control and Prevention (Maine DHHS) runs the state’s private well guidance. We didn’t find a free statewide well testing program in Maine. Certified labs charge for each test, and some county health departments offer lower-cost bacteria and nitrate tests.
- People on private wells
- 510,165
- Share of residents
- 38.4%
- Rank among states
- 25th
- Well users modeled above 10 µg/L arsenic
- 21.2%
Where to get your well tested in Maine
- Maine Center for Disease Control and Prevention (Maine DHHS): Private Well Water, the state’s guidance for private well owners.
Free or low-cost testing
We didn’t find a free statewide program in Maine. Certified labs charge per test; county health departments sometimes offer lower-cost bacteria and nitrate tests.
Mail-in lab kits are another option when no local lab is convenient. See well water test kits for what home kits can and can’t tell you.
What to test for
- Every year: total coliform bacteria and nitrate.
- Before buying equipment: pH, hardness, iron, manganese and, if there’s a smell, hydrogen sulfide.
- Based on location: arsenic, uranium and radon, PFAS, and lead in older plumbing.
USGS modeling estimates that about 21.2% of Maine’s private well users have water above the 10 µg/L arsenic limit. Arsenic has no taste or smell, so include it in your first test.
Private wells by county
Estimated people relying on private wells in each Maine county in 2010, the share of residents that represents, and the modeled share of well users with arsenic above 10 µg/L. These are USGS model estimates (2010 population), not measurements of any well. Arsenic is hidden for counties with fewer than 500 well users.
| County | People on wells | Share | Arsenic >10 µg/L |
|---|---|---|---|
| York County | 61,742 | 31.3% | 25.2% |
| Penobscot County | 58,412 | 37.9% | 10.0% |
| Cumberland County | 53,521 | 19.0% | 26.2% |
| Kennebec County | 52,132 | 42.7% | 29.0% |
| Aroostook County | 36,134 | 50.3% | 16.4% |
| Hancock County | 35,636 | 65.5% | 21.8% |
| Oxford County | 32,896 | 56.9% | 6.2% |
| Androscoggin County | 30,993 | 28.8% | 44.1% |
| Somerset County | 26,156 | 50.1% | 21.6% |
| Waldo County | 25,473 | 65.7% | 12.0% |
| Lincoln County | 23,110 | 67.1% | 23.1% |
| Knox County | 18,309 | 46.1% | 12.1% |
Show all 16 counties
| Washington County | 17,968 | 54.7% | 13.8% |
| Sagadahoc County | 15,413 | 43.7% | 41.0% |
| Franklin County | 12,971 | 42.2% | 14.4% |
| Piscataquis County | 9,299 | 53.0% | 15.2% |
Counties with the highest modeled arsenic share: Androscoggin County (44.1%), Sagadahoc County (41.0%), Kennebec County (29.0%), Cumberland County (26.2%), York County (25.2%).
After you get results
Enter your numbers in the test results tool to see what needs treating and in what order. The guide to reading a well water test explains units and limits.
Common questions
Does Maine offer free well water testing?
We didn’t find a free statewide well testing program in Maine. Certified labs charge for each test, and some county health departments offer lower-cost bacteria and nitrate tests.
Who oversees private wells in Maine?
Maine Center for Disease Control and Prevention (Maine DHHS) (Private Well Water) publishes guidance for private well owners. Private wells aren’t covered by the federal Safe Drinking Water Act, so testing and treatment are up to the owner.
How many people use private wells in Maine?
USGS estimates about 510,000 people, or 38.4% of the population in 2010. That ranks 25th of the states covered by the estimate.
What should I test my well for in Maine?
Test every year for total coliform bacteria and nitrate, plus pH, hardness, iron and manganese before buying equipment. Arsenic is a known concern in parts of Maine, so add it to the first test.