The 50 largest wastewater treatment plants in Maine
Ranked by average flow · 32 MGD combined · 97% of the state's reported flow
Bangor Wastewater Treatment Facility in Bangor is the largest publicly owned wastewater treatment plant in Maine by reported average flow, treating about 7.09 million gallons per day. The 50 plants below treat 32 MGD between them, 97% of the flow reported by all 92 plants in the state, and serve about 243,989 people. Every plant links to its profile with permit and compliance data. Treatment technology is shown with a free Klarifi account.
| # | Facility | City | Avg flow (MGD) | Population | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|---|
| 1 | Bangor Wastewater Treatment Facility | Bangor | 7.09 | 38,856 | ME0100781 | Jul 2031 | 14 |
| 2 | Westbrook Waste Water Treatmemt Facility | Westbrook | 3.05 | 23,987 | ME0100846 | Jul 2022 | 26 |
| 3 | Brewer Wastewater Treatment Facility | Brewer | 1.47 | 10,118 | ME0100072 | Nov 2029 | 2 |
| 4 | Sanford Wastewater Treatment Facility | Sanford | 1.42 | 11,904 | ME0100617 | Jul 2023 | 4 |
| 5 | Old Town Wastewater Treatment Facility | Old Town | 1.09 | 9,667 | ME0100471 | Sep 2029 | 2 |
| 6 | Old Orchard Beach Wastewater Treatment Facility | Old Orchard Beach | 0.99 | 8,908 | ME0101524 | May 2020 | 13 |
| 7 | York Wastewater Treatment Facility | York | 0.99 | 9,400 | ME0101222 | Mar 2030 | 12 |
| 8 | Gardiner WWTF | Gardiner | 0.97 | 9,628 | ME0101702 | Oct 2021 | 1 |
| 9 | Bar Harbor WWTF Main Facility | Bar Harbor | 0.91 | 3,700 | ME0101214 | Jan 2021 | 9 |
| 10 | Falmouth Waste Water Treatment Facility | Falmouth | 0.89 | 12,575 | ME0100218 | Dec 2023 | 3 |
| 11 | Canton Wastewater Treatment Facility | Canton | 0.77 | 410 | ME0102067 | Oct 2029 | 4 |
| 12 | Ellsworth Water Pollution Control Facility | Ellsworth | 0.74 | 2,360 | ME0102865 | Dec 2022 | 0 |
| 13 | Pittsfield Wastewater Treatment Facility | Pittsfield | 0.71 | 3,908 | ME0100528 | Jun 2030 | 20 |
| 14 | Anson Madison Wastewater Treatment Facility | Madison | 0.67 | 4,620 | ME0101389 | Apr 2031 | 2 |
| 15 | Camden Wastewater Treatment Facility | Camden | 0.67 | 3,731 | ME0100137 | Dec 2023 | 6 |
| 16 | Belfast Wastewater Treatment Facility | Belfast | 0.59 | 6,668 | ME0101532 | Feb 2021 | 0 |
| 17 | Yarmouth Wastewater Treatiment Facility | Yarmouth | 0.55 | 5,770 | ME0100765 | Aug 2022 | 3 |
| 18 | Skowhegan Wastewater Treatment Facility | Skowhegan | 0.54 | 4,536 | ME0100625 | Apr 2031 | 90 |
| 19 | Calais Wastewater Treatment Facility | Calais | 0.52 | 3,123 | ME0100129 | Nov 2021 | 9 |
| 20 | Ogunquit Wastewater Treatment Facility | Ogunquit | 0.49 | 1,000 | ME0100986 | Nov 2023 | 8 |
| 21 | Unity Ud WWTF | Unity | 0.47 | 1,500 | ME0101150 | Oct 2022 | 8 |
| 22 | Livermore Falls WWTF | Livermore Falls | 0.45 | 3,704 | ME0100315 | Oct 2029 | 15 |
| 23 | Lisbon Wastewater Treatment Facility | Lisbon | 0.45 | 4,825 | ME0100307 | Oct 2029 | 4 |
| 24 | Madawaska WWTF | Madawaska | 0.42 | 3,059 | ME0101681 | Dec 2024 | 6 |
| 25 | Jackman Wastewater Treatment Facility | Jackman | 0.35 | 534 | ME0100978 | Oct 2024 | 0 |
| 26 | Norway Wastewater Treatment Facility | Norway | 0.33 | 5,031 | ME0100455 | Aug 2030 | 0 |
| 27 | Kennebunkport Wastewater Treatment Facility | Kennebunkport | 0.32 | 3,700 | ME0101184 | Nov 2026 | 31 |
| 28 | Bucksport Wastewater Treatment Facility | Bucksport | 0.31 | 3,168 | ME0100111 | Jan 2023 | 9 |
| 29 | Dover-Foxcroft Wastewater Treatment Facility | Dover-Foxcroft | 0.31 | 3,100 | ME0100501 | Feb 2028 | 6 |
| 30 | Freeport Wastewater Treatment Facility | Freeport | 0.3 | 2,452 | ME0101036 | Feb 2021 | 4 |
| 31 | Ft Fairfield Wastewater Treatment Facility | Fort Fairfield | 0.27 | 1,663 | ME0100226 | May 2022 | 11 |
| 32 | South Berwick Sd WWTF | South Berwick | 0.25 | 3,300 | ME0100820 | Jun 2030 | 2 |
| 33 | Fort Kent WWTF | Fort Kent | 0.24 | 1,893 | ME0102369 | Dec 2021 | 2 |
| 34 | South Cape Elizabeth WWTF | Cape Elizabeth | 0.22 | 4,162 | ME0102121 | Dec 2021 | 16 |
| 35 | Newport Wastewater Treatement Facility | Newport | 0.22 | 2,052 | ME0100447 | Mar 2028 | 2 |
| 36 | Machias Wastewater Treatment Facility | Machias | 0.21 | 1,335 | ME0100323 | Mar 2021 | 2 |
| 37 | Northeast Harbor Wastewater Treatment Facility | Northeast Harbor | 0.2 | 640 | ME0101346 | May 2025 | 7 |
| 38 | Milo Wastewater Treatment Facility | Milo | 0.2 | 1,510 | ME0100439 | Mar 2028 | 15 |
| 39 | Wiscasset WWTF | Wiscasset | 0.17 | 2,247 | ME0100757 | Aug 2025 | 14 |
| 40 | Bingham WWTF | Bingham | 0.16 | 866 | ME0100056 | Feb 2029 | 28 |
| 41 | Warren Wastewater Treatment Facility | Warren | 0.14 | 1,630 | ME0102253 | Mar 2030 | 0 |
| 42 | Clinton WWTF | Clinton | 0.14 | 1,400 | ME0101699 | Jun 2030 | 0 |
| 43 | Richmond Wastewater Treatment Facility | Richmond | 0.14 | 1,419 | ME0100587 | May 2030 | 8 |
| 44 | Veazie WWTF | Veazie | 0.13 | 1,898 | ME0100706 | Sep 2030 | 13 |
| 45 | Eastport WWTF | Eastport | 0.12 | 1,183 | ME0100200 | Feb 2030 | 2 |
| 46 | Ashland Wastwater Treatment Facility | Ashland | 0.11 | 253 | ME0101087 | May 2027 | 28 |
| 47 | Rockland Wastewater Treatment Facility | Rockland | 0.1 | 7,600 | ME0100595 | Jul 2021 | 3 |
| 48 | Howland WWTF | Howland | 0.1 | 1,556 | ME0101788 | Sep 2031 | 0 |
| 49 | Limerick WWTF | Limerick | 0.1 | 640 | ME0100871 | Oct 2020 | 64 |
| 50 | Hartland Wastewater Treatment Facility | Hartland | 0.1 | 800 | ME0101443 | May 2023 | 0 |
Treatment technology for each plant is shown with a free Klarifi account. Create one →
Largest plants 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 October 26, 2026.
Wastewater terms: WWTP · POTW · MGD · NPDES permit · Filter press · FOG · all terms
Cite this page
Journalists, researchers and educators are welcome to quote these figures. Please credit Klarifi as the source and link to this page.
Klarifi. “The 50 largest wastewater treatment plants in Maine (2026).” Updated October 26, 2026. https://klarifi.io/facilities/maine/largestNeed a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.