Maine Private Well Water Quality 2026

Maine’s PFAS Crisis: Sludge, Farms and Private Wells

Maine’s PFAS contamination story began in 2016, when testing of a water well at a dairy farm in Arundel revealed elevated levels of PFAS chemicals. The source: wastewater sludge and septage that had been routinely spread on Maine farmland as fertiliser from the 1970s through the 2000s — a state-licensed practice that was not understood to pose a PFAS risk until 2019. The chemicals leached from treated fields into soil and from soil into groundwater, reaching private drinking water wells across the state.

What followed was the most systematic state-level PFAS investigation in the country. Maine’s Department of Environmental Protection (DEP) was required by law to test all sites where sludge or septage had been land-applied. The original estimate was 700 sites — but as of the DEP’s 2025 report, the number of identified investigation sites has grown to 1,066, with more potentially still to be found. By January 2025, the investigation had confirmed PFAS contamination at more than 100 Maine farms and 500 residential properties.

The DEP has installed around 660 water filtration systems on private residential supplies where PFAS was found to exceed Maine’s interim standard — and has spent approximately $19.9 million on the investigation through December 2024. Additional contamination sources include:

• Military bases and firefighting foam (AFFF) — Brunswick Naval Air Station has been a documented PFAS source. In 2024, a spill of AFFF foam in Brunswick raised fresh contamination concerns for surrounding groundwater.
• Landfill leachate — Maine DEP conducted five rounds of landfill leachate testing between 2021 and 2023. PFAS was found in leachate from multiple landfills, and in 2025 a new law was enacted to protect groundwater and surface water from landfill leachate PFAS.
• Institutional sources — Research published in December 2024 in Environmental Health Perspectives found that floor wax and other PFAS-containing school products may have contaminated private wells near rural Maine schools. Of 196 schools tested through November 2024, 31% exceeded federal PFAS limits.
• Tremont, Mount Desert Island — Community testing of 74 private wells found 36 with detectable PFAS and 13 above Maine’s interim standard of 20 ppt for six PFAS combined — in an area far from major industrial sources.

Maine was the first state to ban the land application of PFAS-contaminated sludge, doing so in 2022. The state also adopted its own enforceable drinking water standards for PFAS, and in 2025 the legislature passed two further bills — requiring landlords to test rental property wells for PFAS, and creating state-funded testing for low-income households. Maine has been among the most proactive states on PFAS regulation, but the scale of historical contamination means the well water risk remains very real.

Arsenic, Radon and Uranium in Maine Well Water

Maine’s bedrock geology creates a distinct set of naturally occurring risks that exist independently of industrial contamination. Maine CDC confirms that many wells across the state contain arsenic, radon, uranium or other naturally occurring chemicals at levels that can cause serious health effects including cancer. These contaminants are colourless and tasteless — they cannot be detected without laboratory testing.

Arsenic is one of the most widespread well water concerns in Maine. The state’s granite-rich geology releases arsenic into groundwater, and the Maine Tracking Network holds data from over 45,000 well water tests covering six potentially hazardous substances. The Maine CDC recommends arsenic testing every three to five years, with specific risk maps available by county and town on the Maine Tracking Network portal. The EPA’s MCL for arsenic is 10 ppb — exceeding this level is a health risk that requires action.

Radon is found in elevated concentrations in Maine well water, particularly where wells are drilled into granite bedrock. Studies have shown that close to one in five Maine wells has radon concentrations above the Maine Bureau of Health’s recommended limit of 4,000 pCi/L. In greater Augusta specifically, approximately 29% of private bedrock well samples showed radon above that level. Radon in water contributes to airborne radon exposure when water is used for bathing and cooking.

Uranium is also a documented risk in Maine bedrock wells, particularly near granitic intrusions. Research from the greater Augusta area found that around 4.8% of sampled bedrock wells contained uranium above the EPA’s MCL of 30 µg/L. Uranium is linked to kidney damage and cancer risk. Maine CDC recommends testing for uranium every three to five years.

Bacteria and Nitrate Risks in Maine Wells

Maine CDC recommends annual testing of all private wells for coliform bacteria, E. coli, and nitrates. Bacteria can enter a well when the wellhead is improperly sealed, during flooding events, or where a septic system is too close to the well casing. Older wells are at higher risk. Nitrate contamination from agricultural activity is a lower risk in Maine than in heavily farmed Midwest states, but remains a concern near farms and in shallow wells — it is particularly dangerous for infants under six months.

Regulatory Situation for Maine Well Owners

Private residential wells in Maine are not regulated under the federal Safe Drinking Water Act. Testing and treatment of well water remain the individual owner’s responsibility. However, Maine is one of the more proactive states when it comes to supporting well owners near known contamination sites.

Where the DEP’s sludge and septage investigation confirms that a private well exceeds Maine’s interim PFAS drinking water standard of 20 ppt for six PFAS combined — and the contamination can be linked to a licensed land application site — the DEP will provide bottled water and fund the installation of a filtration system. The federal standard of 4 ppt for PFOA and PFOS (set April 2024) is lower than Maine’s current interim standard, meaning some wells that fall between the two thresholds are not currently covered by state-funded remediation.

For PFAS contamination from other sources — such as military bases, landfill leachate, or unknown origins — private well owners bear the full cost of testing and treatment themselves. Maine CDC provides free technical assistance and can advise on certified labs and appropriate testing panels.

See our Maine municipal water quality page for city-by-city tap water data, or use our live boil water notice tracker for active advisories across the state.

Known High-Risk Areas in Maine

If you live near any of the following locations, well water testing is urgent — not precautionary.

How to Test Your Maine Well Water — and What to Do Next

Maine CDC recommends testing well water annually for bacteria, E. coli, and nitrates, and every three to five years for arsenic, radon, uranium, fluoride, lead, and manganese. Given Maine’s PFAS contamination picture, a PFAS test should be carried out at least once — and urgently if your property is near any of the high-risk areas listed above.

Contact Maine CDC’s free technical assistance service at wellwater.maine.gov or call 1-866-292-3474 to discuss your property’s specific risk profile and get a list of certified laboratories. The Maine Tracking Network’s data portal (data.mainepublichealth.gov) shows contaminant levels by town, which can help you understand what risks are most common in your area.

If you believe your well may be affected by DEP-licensed sludge application, check the interactive PFAS Investigation Map at maine.gov/dep. Where contamination above the state threshold can be linked to a licensed land application site, DEP is funding filtration system installation.

For filter options, our well water filter guide covers reverse osmosis for PFAS and arsenic, radon treatment options, and whole-house well systems for comprehensive protection. Browse our full water filter solutions page or check your ZIP code for local water quality context.

For other Northeast well water risks, see our pages on Michigan wells, North Carolina wells, and Pennsylvania wells. Return to the private well water directory to find your state.