Maine Water Quality Rankings 2026: Best & Worst Cities

This page ranks the 11 Maine cities whose water systems we have matched to EPA records. Every city starts at 100 points and loses points for health-based EPA violations in the last five years (SDWIS 2026Q2), its most recent Lead and Copper Rule 90th-percentile result, PFAS detected in EPA's 2023–2026 UCMR5 monitoring, and 2012–2019 compliance samples that averaged near or above a limit. Letters follow fixed bands (A ≥90, B ≥80, C ≥70, D ≥60, F below 60). Cities run from the highest score (Biddeford) down to the lowest (Sanford); ties are ordered by population served. See the full scoring methodology for every deduction and the data vintages. 4 further Maine cities are listed at the bottom without a grade because we have not yet matched them to an EPA water system.

What your city's grade means

An A or B grade points to water that consistently tests within federal safety limits, while a C suggests moderate issues worth watching and a D or F flags contaminants or compliance problems serious enough to act on. These grades describe system-level water leaving the treatment plant — they can't account for your home's own plumbing, so older houses with lead service lines or fixtures can add contaminants after the water arrives. For a contaminant-by-contaminant view, see the Maine contaminant breakdown or drill into the county-level rankings.

What Maine residents should do

• Find your city in the ranking below and open its full report for its violation history, lead results and PFAS table.
• See how Maine compares against the best-rated and worst-rated cities nationwide.
• Test your home's water if you have concerns — the most common issues involve lead, PFAS, and arsenic.
• Check whether your utility still has lead service lines in Maine — EPA's inventory counts lead pipes by water system, a risk that plant-level grades cannot capture. Read the lead guide for testing and filter options.
• If treatment makes sense for your situation, compare certified water filters matched to the contaminants found in your area.

We track 15 cities in Maine. 11 of them are matched to an active EPA-registered community water system (PWSID). Those 10 systems report serving 320,968 people in EPA's Safe Drinking Water Information System (SDWIS).

Of 11 cities of the 15 Maine cities we can grade from EPA records, 10 cities (91%) grade B or better, 1 sit in the C range and 0 grade D or F. The average score is 94/100. 4 cities are not graded because they have not been matched to an EPA system yet.

None of the 11 graded systems has a health-based EPA violation in the last five years; the 11 violations on file in that window are monitoring or reporting lapses.

11 cities have a Lead and Copper Rule 90th-percentile result from 2020 or later: 2 cities at 5 ppb or more.

EPA's UCMR5 PFAS monitoring (2023–2026) covers 11 cities: PFAS were detected in 2 cities, and PFOA or PFOS reached EPA's 4 ppt limit in 2 cities.

Biddeford scores highest (100) and Sanford lowest (74), a 26-point spread.

Lead pipes are the part of tap-water risk a treatment-plant grade cannot see, so start with EPA's service line inventory (Q2 2026 snapshot). 771 Maine systems inventoried 291,891 service lines: 29 confirmed lead plus 1,575 galvanized lines requiring replacement, spread across 5 systems. Another 41,667 lines (14%) are still of unknown material, which EPA counts as possible lead until verified.

Of the 10 city-linked Maine utilities with an inventory on file, 4 report at least one lead or galvanized-requiring-replacement line, 1 reports none but still has a quarter or more of its lines unverified, and 5 report no lead with most lines verified. PORTLAND WATER DISTRICT-GREATER, which serves Portland and 135,068 people, is the biggest and reports no lead lines and 100% of lines verified non-lead. The most lead lines among city-linked systems belong to GREATER AUGUSTA UTILITY DISTRICT (Augusta): 9.

Maine's guide on this site singles out arsenic, uranium, PFAS, and lead. Arsenic (EPA MCL 0.010 mg/L (10 ppb)) is linked to skin damage, circulatory problems and increased cancer risk; Uranium (EPA MCL 30 µg/L) increases cancer risk and is toxic to the kidneys; PFAS (EPA 2024 MCLs of 4.0 ppt for PFOA and PFOS) are linked to immune, developmental, liver and some cancer effects; Lead (EPA action level 0.015 mg/L (15 ppb); health goal 0) harms brain development in children and raises blood pressure and kidney risk in adults.

Where a system draws its water shapes which of these show up. Arsenic and uranium are naturally occurring and tend to show up in groundwater, leaching from bedrock into aquifers rather than arriving from pollution. PFAS are tied to specific sites — industrial discharges, firefighting-foam use at airports and bases — rather than to geology, so contamination is local and can affect either source type. Lead is different again: it enters after treatment from service lines and household plumbing, which is why the inventory figures above matter more than plant-level results. Your utility's Consumer Confidence Report names your source.

The best water quality in Maine is found in Biddeford with a score of 100/100 and a grade of A. This puts Biddeford among the top-performing cities in the country for drinking water safety.

The most concerning water quality is in Sanford scoring 74/100 with a grade of C. Residents may want to consider home water testing and filtration options.

The statewide average score is 94/100, which is 6 points above the national average of 88/100. Over half (73%) of Maine cities score above the national average, though some areas face challenges.