States/NH

Sewer overflows in New Hampshire

Sewer overflow record — reported spills, the worst utilities, and how often overflows reached waterways in New Hampshire.

Reported events
169
Total volume
22.7M gal
Reached waterways
0(0%)
Latest event
Jun 20, 2026

Worst utilities in New Hampshire

Ranked by number of reported overflow events.

#UtilityEventsVolumeReached water
1MANCHESTER SANITARY SEWER SYSTEM7117.3M gal0
2KEENE SANITARY SEWER SYSTEM10410 gal0
3LEBANON-HANOVER SANITARY SEWER SYSTEM939K gal0
4MERRIMACK SANITARY SEWER SYSTEM912K gal0
5JAFFREY SANITARY SEWER SYSTEM98K gal0
6NASHUA SANITARY SEWER SYSTEM75.2M gal0
7PLYMOUTH SANITARY SEWER SYSTEM625K gal0
8HAMPTON SANITARY SEWER SYSTEM52K gal0
9LITTLETON SANITARY SEWER SYSTEM55K gal0
10NEWMARKET SANITARY SEWER SYSTEM51K gal0
11WINNIPESAUKEE RIVER BASIN PROGRAM SANITARY SEWER S412K gal0
12SEABROOK SANITARY SEWER SYSTEM4110K gal0
13EXETER SANITARY SEWER SYSTEM410K gal0
14NEWPORT SANITARY SEWER SYSTEM3150 gal0
15COLEBROOK SANITARY SEWER SYSTEM31K gal0
16HOOKSETT SANITARY SEWER SYSTEM34K gal0
17CHARLESTOWN SANITARY SEWER SYSTEM24 gal0
18PORTSMOUTH-PIERCE ISLAND SANITARY SEWER SYSTEM211 gal0
19ROCHESTER SANITARY SEWER SYSTEM214K gal0
20CLAREMONT SANITARY SEWER SYSTEM1500 gal0
21LACONIA SANITARY SEWER SYSTEM11 gal0
22PITTSFIELD SANITARY SEWER SYSTEM1300 gal0
23CONCORD-HALL STREET SANITARY SEWER SYSTEM1400 gal0
24CONCORD-PENACOOK SANITARY SEWER SYSTEM11K gal0
25NEWINGTON SANITARY SEWER SYSTEM10 gal0

Biggest spills in New Hampshire

The largest single reported overflow events.