Oxidation ditches: wastewater treatment plants in New Hampshire
5 plants · 11% of the state · 1 MGD combined
Klarifi identifies 5 publicly owned wastewater treatment plants with oxidation ditches in New Hampshire, 11% of the 46 plants in the state (1 MGD combined). The largest is Littleton Wastewater Treatment Plant in Littleton at 0.27 MGD.
Oxidation ditches are ring-shaped activated sludge reactors with long retention times, common at plants between 0.5 and 10 MGD. They are recognisable from the air by their looped channels and rely on surface aerators or brush rotors, which are frequent replacement and energy-efficiency projects.
The largest oxidation ditch plants in New Hampshire
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Littleton Wastewater Treatment Plant | Littleton | 0.27 | NH0100153 | Oct 2025 | 17 |
| 2 | Sunapee, Town Of-WWTP | Sunapee | 0.22 | NHG580017 | Nov 2026 | 27 |
| 3 | Town Of Bristol WWTF | Bristol | 0.21 | NHG580021 | Nov 2026 | 0 |
| 4 | Woodstock WWTF | Woodstock | 0.08 | NHG580020 | Nov 2026 | 29 |
| 5 | Hinsdale Wastewater Treatment Plant | Hinsdale | 0.07 | NHG580016 | Nov 2026 | 6 |
Contacts and project signals for every plant on this list
Klarifi adds verified decision-maker contacts, permit limits, discharge monitoring data and the capital projects planned in each city, filterable by technology, size and compliance record.
Other technologies in New Hampshire
Oxidation ditches in other states
Oxidation ditches in New Hampshire: 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 11, 2026.