Wastewater treatment plants in Maine
85 facilities · 19 MGD combined flow
Klarifi tracks 85 publicly owned wastewater treatment plants in Maine with a combined average flow of 19 MGD, serving about 248,949 residents. 2 plants treat more than 1 MGD and 0 more than 10 MGD; 30 use lagoon systems and 23 have digesters or biogas infrastructure. The largest is Bangor Wastewater Treatment Facility in Bangor at 4.38 MGD. 3 NPDES permits expire this year and 6 next year.
Every plant below links to a profile with average and design flow, the NPDES permit and its expiry, a three-year compliance snapshot and the capital projects planned in its city. Treatment technology and verified contacts are shown with a free Klarifi account.
85 plant locations in Maine; dot size follows average flow.
NPDES permits and renewals in Maine
Every plant discharges under an NPDES permit that is renewed every five years, usually with tighter limits. The renewal year is the year a plant budgets for upgrades.
Largest wastewater treatment plants in Maine
| Facility | City | Avg flow (MGD) | Design (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| Bangor Wastewater Treatment Facility | Bangor | 4.38 | 18 | ME0100781 | Jul 2031 | 14 |
| Westbrook Waste Water Treatmemt Facility | Westbrook | 2.5 | 4.54 | ME0100846 | Jul 2022 | 26 |
| Brewer Wastewater Treatment Facility | Brewer | 0.92 | 5.19 | ME0100072 | Nov 2029 | 2 |
| Old Orchard Beach Wastewater Treatment Facility | Old Orchard Beach | 0.9 | 3.5 | ME0101524 | May 2020 | 11 |
| Bar Harbor WWTF Main Facility | Bar Harbor | 0.82 | 2 | ME0101214 | Jan 2021 | 9 |
| Falmouth Waste Water Treatment Facility | Falmouth | 0.7 | 1.56 | ME0100218 | Dec 2023 | 3 |
| York Wastewater Treatment Facility | York | 0.67 | 3 | ME0101222 | Mar 2030 | 12 |
| Old Town Wastewater Treatment Facility | Old Town | 0.63 | 3.5 | ME0100471 | Sep 2029 | 2 |
| Anson Madison Wastewater Treatment Facility | Madison | 0.6 | 7.84 | ME0101389 | Apr 2031 | 2 |
| Ogunquit Wastewater Treatment Facility | Ogunquit | 0.54 | 1.28 | ME0100986 | Nov 2023 | 8 |
Treatment technology for each plant is shown with a free Klarifi account. Create one →
Maine plants by treatment technology
All 85 plants in Maine
Wastewater treatment in Maine: questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed September 14, 2026.