How many public water systems are in New Hampshire?

New Hampshire has 2,443 active public water systems in EPA SDWIS records, including 706 community water systems. Together they report serving 1.2M people.

What is the largest water system in New Hampshire?

Manchester Water Works is the largest active public water system in New Hampshire, serving a reported 123,500 people.

Does New Hampshire rely more on groundwater or surface water?

97.3% of New Hampshire's active public water systems draw primarily on groundwater and 2.7% on surface water (including purchased supplies).

New Hampshire public water systems

2,443 active systems regulated under the Safe Drinking Water Act, serving a reported 1.2M people across 15 counties.

Dataset updated July 2026 . Source: EPA SDWIS/ECHO, refreshed quarterly.

Active systems

2,443

Population served

1.2M

Community systems

706

Groundwater share

97.3%

System types in New Hampshire

706

Community water system

455

Non-transient non-community water system

1,282

Transient non-community water system

Largest water systems in New Hampshire

The largest active public water systems in New Hampshire by population served
#	Water system	County	Population served	Type	Source
1	Manchester Water Works	Hillsborough	123,500	Community	Surface water
2	Pennichuck Water Works	Hillsborough	89,073	Community	Surface water
3	Concord Water Dept	Merrimack	44,215	Community	Surface water
4	Portsmouth Water Works	Rockingham	33,000	Community	Surface water
5	Keene Water Dept	Cheshire	30,000	Community	Surface water
6	Dover Water Dept	Strafford	29,000	Community	Groundwater
7	Merrimack Village Dist	Hillsborough	25,500	Community	Groundwater
8	Rochester Water Dept	Strafford	25,000	Community	Surface water
9	Salem Water Dept	Rockingham	21,000	Community	Surface water
10	Aquarion Water/Nh	Rockingham	18,950	Community	Groundwater
11	Derry Water Dept	Rockingham	17,290	Community	Purchased surface water
12	Laconia Water Works	Belknap	17,000	Community	Surface water
13	Hudson Water Dept	Hillsborough	16,700	Community	Groundwater
14	Unh/Durham Water Sys	Strafford	16,000	Community	Surface water
15	Seabrook Water Dept	Rockingham	14,000	Community	Groundwater
16	Lebanon Water Dept	Grafton	13,600	Community	Surface water
17	Exeter Water Dept	Rockingham	12,236	Community	Surface water
18	Somersworth Water Works	Strafford	12,000	Community	Surface water
19	Pease Trade Port	Rockingham	9,900	Community	Groundwater
20	Hanover Water Dept	Grafton	9,600	Community	Surface water
21	Berlin Water Works	Coos	9,575	Community	Surface water
22	Milford Water Utilities Dept	Hillsborough	9,500	Community	Purchased surface water
23	Claremont Water Dept	Sullivan	9,000	Community	Surface water
24	Franklin Water Works	Merrimack	7,200	Community	Groundwater
25	Hampstead Area Water	Rockingham	7,153	Community	Purchased surface water

By county

Rockingham551 systems Carroll364 systems Hillsborough278 systems Grafton270 systems Belknap256 systems Merrimack244 systems Cheshire167 systems Strafford132 systems Coos111 systems Sullivan65 systems

Somerset1 systems

Antrim1 systems

Kent1 systems

Woodford1 systems

Muskegon1 systems