Well Water in Maine
Contaminant risks, testing requirements, and treatment recommendations for private well owners in Maine.
Maine Geology and Groundwater
Maine sits on Glacial deposits over granitic bedrock. This geology directly determines what contaminants are likely in private well water. Based on this geology, Maine well owners face elevated risk for arsenic from natural bedrock, radon from granitic geology, PFAS from industrial/military sites, uranium from bedrock geology.
Contaminant Risk Profile
| Contaminant | Risk Level | Why |
|---|---|---|
| Arsenic | Elevated risk | Natural occurrence in bedrock. Carcinogen with no safe level. EPA MCL: 10 ppb. |
| Nitrate | Low risk | Generally low outside of agricultural areas. |
| Radon | Elevated risk | Granitic and metamorphic bedrock produces radon gas. Inhaled from water during showering. |
| PFAS | Elevated risk | Military bases, industrial sites, or manufacturing in this state have contaminated groundwater. |
| Iron/Manganese | Moderate risk | Found in some wells depending on local geology. |
| Uranium | Elevated risk | Natural occurrence in granitic/metamorphic bedrock. EPA MCL: 30 ppb. |
| Fluoride | Moderate risk | Some wells may have naturally elevated levels. |
How Maine Compares: Municipal Water Data
CheckMyTap tracks water quality for 8 cities in Maine. While these numbers reflect municipal water (not private wells), they indicate the baseline mineral content of Maine's water sources. Private wells often draw from the same aquifers but with less treatment.
| Metric | Maine Average | National Average |
|---|---|---|
| Hardness | 22 PPM (soft) | 170 PPM |
| Hardness range | 10 - 44 PPM | 25 - 400+ PPM |
| Lead (avg municipal) | 3.2 ppb | 3.2 ppb |
| Nitrate (avg municipal) | 1 mg/L | 1.1 mg/L |
| Cities with PFAS detected | 1 of 8 | ~45% nationally |
| Cities exceeding PFAS MCL (4 ppt) | 1 |
Hardest water in Maine: Bangor (44 PPM), Lewiston (37 PPM), Augusta (20 PPM), Auburn (18 PPM), Waterville (16 PPM).
Softest water: Portland (10 PPM), South Portland (12 PPM), Biddeford (15 PPM).
Testing Requirements in Maine
Maine requires well water testing at property transfer. Landlords must test for arsenic and disclose results to tenants. Regardless of state requirements, the EPA recommends testing annually for:
- Every year: Total coliform bacteria, E. coli, nitrate, pH, and total dissolved solids
- At least once: Arsenic, lead, copper, fluoride, and any contaminant identified as a local risk
- Recommended for Maine: Radon in water (granitic bedrock states have higher risk)
- Recommended for Maine: PFAS panel, especially if near military bases or industrial sites
- Recommended for Maine: Uranium, especially in areas with granitic or metamorphic bedrock
- After events: Retest after flooding, well repairs, nearby construction, or any change in taste/color/odor
Recommended Treatment for Maine Wells
Based on Maine's geology and common contaminant risks, these treatment systems address the most likely issues:
Removes arsenic, uranium, and most dissolved contaminants from drinking water
Learn moreMost effective radon-in-water removal (95-99%). GAC is an alternative for lower levels
Kills bacteria and viruses without chemicals. Recommended for all well water systems
Frequently Asked Questions
Is well water in Maine safe to drink?
Well water quality in Maine varies significantly by location and geology. Maine sits on Glacial deposits over granitic bedrock. Key concerns include arsenic from natural bedrock, radon from granitic geology, PFAS from industrial/military sites, uranium from bedrock geology. The only way to know your specific water quality is to test it. Use our free interpreter to understand your results.
How often should I test my well water in Maine?
The EPA recommends testing annually for bacteria (total coliform, E. coli), nitrate, total dissolved solids, and pH. Given Maine's arsenic risk, test for arsenic at least once and after any changes to your well. Radon testing is also recommended in Maine. Test more frequently if you notice changes in taste, color, or odor, or after flooding, nearby construction, or well repairs.
Does Maine require well water testing?
Maine has mandatory testing requirements. Landlords must test for arsenic and disclose results to tenants. However, the EPA strongly recommends annual testing regardless of state requirements. Your county health department may have additional local requirements.
What is the average water hardness in Maine?
Municipal water in Maine averages 22 PPM across 8 cities tracked by CheckMyTap, ranging from 10 to 44 PPM. Private well water typically runs 20-50% harder than city water because groundwater has more contact time with mineral formations. Many Maine well owners have manageable hardness levels, though local variation is significant. Check your city's data.