TapGraded

Connecticut water quality

Connecticut has 2,373 active public water systems (10,873 on file total), 505 of them graded by TapGraded.

Grade distribution

Biggest water systems

B

REGIONAL WATER AUTHORITY

NEW HAVEN, CT · 418,900 served

A

METROPOLITAN DISTRICT COMMISSION

HARTFORD, CT · 390,887 served

B

AQUARION-EASTERN FAIRFIELD COUNTY

SHELTON, CT · 351,756 served

C

AQUARION-STAMFORD

SHELTON, CT · 119,214 served

A

WATERBURY WATER DEPARTMENT

WATERBURY, CT · 107,271 served

C

CTWC - NORTHERN REG-WESTERN SYSTEM

CLINTON, CT · 101,313 served

A

NEW BRITAIN WATER DEPARTMENT

NEW BRITAIN, CT · 73,534 served

C

DANBURY WATER DEPARTMENT

DANBURY, CT · 62,055 served

C

MERIDEN WATER DIVISION

MERIDEN, CT · 58,441 served

C

AQUARION-GREENWICH

SHELTON, CT · 53,297 served

Lowest-graded systems

Active, graded systems serving at least 10,000 people, ordered by lowest Tap Grade first.

C

AQUARION-PLAINVILLE REGIONAL

SHELTON, CT · 18,231 served

C

DANBURY WATER DEPARTMENT

DANBURY, CT · 62,055 served

C

SOUTHINGTON WATER DEPARTMENT

SOUTHINGTON, CT · 43,069 served

C

WALLINGFORD WATER DEPARTMENT

WALLINGFORD, CT · 37,267 served

C

AQUARION-NEW MILFORD REGIONAL

SHELTON, CT · 13,331 served

C

MERIDEN WATER DIVISION

MERIDEN, CT · 58,441 served

C

CTWC - UNIONVILLE SYSTEM

CLINTON, CT · 14,693 served

C

MANCHESTER WATER DEPARTMENT

MANCHESTER, CT · 51,198 served

C

BRISTOL WATER DEPARTMENT

BRISTOL, CT · 52,079 served

C

AQUARION WATER/NH

MONROE, CT · 34,000 served

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Source: EPA SDWIS/ECHO · Data as of 2026Q2