Maine’s tap water is generally safe to drink, particularly for residents served by public water systems, which are subject to stringent federal and state regulations. Safety is not universal, however, and the water source is the primary factor determining risk. Maine’s unique geology and the prevalence of private wells mean that water safety is often a localized and individual responsibility. Understanding the specific contaminants and oversight that apply to your water source is important.
Public Water System Safety and Oversight
Public water systems in Maine are overseen by the Maine Drinking Water Program (DWP), part of the Maine Center for Disease Control and Prevention (Maine CDC) within the Maine DHHS. The DWP ensures compliance with the federal Safe Drinking Water Act (SDWA), which sets Maximum Contaminant Levels (MCLs) for various substances. The U.S. Environmental Protection Agency (EPA) has granted the DWP “primacy,” allowing the state to administer and enforce these regulations locally.
Regulated systems, including municipal utilities, must routinely test their water for contaminants such as bacteria, chemicals, and radionuclides. The DWP uses teams for compliance, enforcement, field services, and source water protection. This multi-layered oversight aims to identify and treat contamination before the water reaches the public.
Customers of public water systems receive an annual Consumer Confidence Report (CCR), detailing the system’s water quality data and any violations. Community water systems, defined as those serving at least 15 service connections or 25 year-round residents, must distribute these reports by July 1st each year. These reports provide transparent, localized data, allowing consumers to review test results against regulatory standards.
Unique Contaminant Risks in Maine
Maine’s bedrock geology presents a challenge for water quality due to the natural presence of certain elements. Arsenic is a widespread concern, particularly in the eastern New England “arsenic belt,” with elevated levels found in groundwater across counties like Kennebec, York, and Hancock. This naturally occurring arsenic leaches from the bedrock into the groundwater, where it is tasteless, odorless, and colorless.
Another geological contaminant is radon, a radioactive gas resulting from the natural decay of uranium found in granite and other rocks. Areas with granitic intrusions, such as the greater Augusta region, often show elevated uranium and radon concentrations in well water. The Maine Bureau of Health recommends that radon in drinking water be no more than 4,000 picocuries per liter (pCi/L).
Emerging contaminants, specifically Per- and polyfluoroalkyl substances (PFAS), also pose a risk and have prompted state action. These “forever chemicals” are used in various products and do not break down easily. Maine established an interim state standard of 20 parts per trillion (ppt) for the combined sum of six specific PFAS chemicals in public water supplies.
Private Well Water: A Separate Safety Concern
Over half of Maine’s population relies on private residential wells for drinking water, a percentage much higher than the national average. Unlike public water systems, private wells are not subject to the federal SDWA or mandated state oversight; testing and treatment responsibility rests solely with the homeowner. This lack of regulation means water quality issues can go undetected.
Private well water is susceptible to contamination from various sources, including the natural geological risks of arsenic and radon. Wells are also vulnerable to localized contamination from bacteria, such as total coliform, which can indicate surface water intrusion or proximity to a septic system. Nitrates are another common concern, often originating from fertilizer runoff or nearby septic systems.
Testing is the only method to confirm the safety of a private well, as these contaminants often have no discernible taste or odor. The Maine CDC recommends that private well owners test their water for common contaminants like bacteria, nitrates, arsenic, and radon. Testing is especially important when purchasing a home, after a new well is drilled, or if the well has been submerged during a flood.
Individual Steps for Water Assurance
Proactive testing is the most effective first step to ensure water safety, regardless of the source. For private well owners, the Maine CDC recommends testing for bacteria and nitrates annually, and for arsenic, radon, and other inorganic contaminants every three to five years. Samples should be sent to a state-certified laboratory, such as the State of Maine Health and Environmental Testing Laboratory, to ensure accurate results.
If testing reveals a contaminant above health guidelines, several treatment options are available. For arsenic removal, a point-of-use reverse osmosis (RO) system or a whole-house adsorption filter is effective. Radon can be removed through aeration systems, which agitate the water to release the gas, or by using granular activated carbon (GAC) filters.
For public water users concerned about taste, odor, or residual chemicals like chlorine, a simple activated carbon filter can be installed on a faucet or as a whole-house system. Specialized filtration systems, including RO and GAC, are also utilized for the removal of emerging contaminants like PFAS. Understanding your water quality profile allows for the selection of the most appropriate filtration technology.