How many public water systems are in Connecticut?

Connecticut has 2,362 active public water systems in EPA SDWIS records, including 482 community water systems. Together they report serving 2.9M people.

What is the largest water system in Connecticut?

Regional Water Authority is the largest active public water system in Connecticut, serving a reported 418,900 people.

Does Connecticut rely more on groundwater or surface water?

96.2% of Connecticut's active public water systems draw primarily on groundwater and 3.8% on surface water (including purchased supplies).

Connecticut public water systems

2,362 active systems regulated under the Safe Drinking Water Act, serving a reported 2.9M people across 20 counties.

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

Active systems

2,362

Population served

2.9M

Community systems

482

Groundwater share

96.2%

System types in Connecticut

482

Community water system

483

Non-transient non-community water system

1,397

Transient non-community water system

Largest water systems in Connecticut

The largest active public water systems in Connecticut by population served
#	Water system	County	Population served	Type	Source
1	Regional Water Authority	New Haven	418,900	Community	Surface water
2	Metropolitan District Commission	Hartford	390,887	Community	Surface water
3	Aquarion-Eastern Fairfield County	Fairfield	351,756	Community	Surface water
4	Aquarion-Stamford	Fairfield	119,214	Community	Surface water
5	Waterbury Water Department	New Haven	107,271	Community	Surface water
6	Ctwc - Northern Reg-Western System	Hartford	101,313	Community	Surface water
7	New Britain Water Department	Hartford	73,534	Community	Surface water
8	Danbury Water Department	Fairfield	62,055	Community	Surface water
9	Meriden Water Division	New Haven	58,441	Community	Surface water
10	Aquarion-Greenwich	Fairfield	53,297	Community	Surface water
11	Bristol Water Department	Hartford	52,079	Community	Surface water
12	Manchester Water Department	Hartford	51,198	Community	Surface water
13	Southington Water Department	Hartford	43,069	Community	Surface water
14	South Norwalk Electric & Water	Fairfield	42,000	Community	Surface water
15	Middletown Water Department	Middlesex	41,019	Community	Surface water
16	Norwalk First Taxing District	Fairfield	40,256	Community	Surface water
17	Torrington Water Company	Litchfield	37,915	Community	Surface water
18	Wallingford Water Department	New Haven	37,267	Community	Surface water
19	Norwich Public Utilities	New London	36,163	Community	Surface water
20	Ctwc - Shoreline Region-Guilford System	New Haven	33,975	Community	Surface water
21	Mohegan Tribal Utility Authority	—	31,961	Community	Purchased surface water
22	Groton Utilities	New London	30,200	Community	Surface water
23	New London Dept. of Public Utilities	New London	27,620	Community	Surface water
24	University of Connecticut - Main Campus	Tolland	27,199	Community	Purchased surface water
25	Mashantucket Pequot Water System	—	26,445	Community	Groundwater under influence of surface water

By county

New London395 systems Litchfield345 systems Fairfield338 systems Tolland297 systems Middlesex276 systems Windham254 systems Hartford219 systems New Haven213 systems Kalkaska6 systems

Aleutians West Census Area2 systems

Columbia2 systems

Aleutians East Borough2 systems

Wayne2 systems

Wood2 systems

Osceola2 systems

Henderson1 systems

Walker1 systems

Lake and Peninsula Borough1 systems

Hays1 systems

Harris1 systems