STATE / TERRITORY LEDGER
Connecticut drinking water system records
EPA’s September 2026 export lists 68 active community water systems in Connecticut, with 10 current-violation flags and 1 serious-violator flags among covered systems serving at least 2,500 people.
Source: EPA SDWIS system-search export · Active community systems · Snapshot 13 Sep 2026
Systems68active CWS · pop. 2,500+
Population served2,670,846reported total; may overlap
Current violation flag14.7%10 systems
Serious-violator flag1.5%1 systems
01 / LARGEST SYSTEMS
Connecticut community water systems
EPA’s covered Connecticut records include 68 active community systems reporting a combined population-served total of 2,670,846, which may overlap.
Population served is a system-reported service figure. It is not a count of unique state residents.
| Water system | Population served | Primary source | Current export status |
|---|---|---|---|
| Regional Water AuthorityCT0930011 | 418,900 | Surface water | No current violation flagged |
| Metropolitan District CommissionCT0640011 | 390,887 | Surface water | No current violation flagged |
| Aquarion-Eastern Fairfield CountyCT0150011 | 351,756 | Surface water | No current violation flagged |
| Aquarion-StamfordCT1350011 | 119,214 | Surface water | No current violation flagged |
| Waterbury Water DepartmentCT1510011 | 107,271 | Surface water | No current violation flagged |
| Ctwc - Northern Reg-Western SystemCT0473011 | 101,313 | Surface water | Other current violation flag |
| New Britain Water DepartmentCT0890011 | 73,534 | Surface water | No current violation flagged |
| Danbury Water DepartmentCT0340011 | 62,055 | Surface water | No current violation flagged |
| Meriden Water DivisionCT0800011 | 58,441 | Surface water | No current violation flagged |
| Aquarion-GreenwichCT0570011 | 53,297 | Surface water | No current violation flagged |
| Bristol Water DepartmentCT0170011 | 52,079 | Surface water | No current violation flagged |
| Manchester Water DepartmentCT0770021 | 51,198 | Surface water | No current violation flagged |
| Southington Water DepartmentCT1310011 | 43,069 | Surface water | No current violation flagged |
| South Norwalk Electric & WaterCT1030021 | 42,000 | Surface water | No current violation flagged |
| Middletown Water DepartmentCT0830011 | 41,019 | Surface water | No current violation flagged |
| Norwalk First Taxing DistrictCT1030011 | 40,256 | Surface water | No current violation flagged |
| Torrington Water CompanyCT1430011 | 37,915 | Surface water | No current violation flagged |
| Wallingford Water DepartmentCT1480011 | 37,267 | Surface water | No current violation flagged |
| Norwich Public UtilitiesCT1040011 | 36,163 | Surface water | No current violation flagged |
| Ctwc - Shoreline Region-Guilford SystemCT0608011 | 33,975 | Surface water | No current violation flagged |
| Mohegan Tribal Utility Authority010109005 | 31,961 | Surface water purchased | No current violation flagged |
| Groton UtilitiesCT0590011 | 30,200 | Surface water | No current violation flagged |
| New London Dept. Of Public UtilitiesCT0950011 | 27,620 | Surface water | No current violation flagged |
| University Of Connecticut - Main CampusCT0780021 | 27,199 | Surface water purchased | No current violation flagged |
| Ctwc - Naugatuck Region-Central SystemCT0880011 | 22,735 | Surface water | No current violation flagged |
| Mashantucket Pequot Water System010106001 | 22,171 | Groundwater under influence of surface water | No current violation flagged |
| Windham Water WorksCT1630011 | 21,214 | Surface water | No current violation flagged |
| Aquarion-DarienCT0350011 | 18,737 | Surface water purchased | No current violation flagged |
| Hazardville Water CompanyCT0490021 | 18,544 | Ground water | No current violation flagged |
| Aquarion-Plainville RegionalCT1100011 | 18,231 | Ground water | Current serious-violator flag |
| Waterford WpcaCT1520071 | 16,578 | Surface water purchased | Other current violation flag |
| East Lyme Water & Sewer CommissionCT0450011 | 15,245 | Surface water purchased | No current violation flagged |
| Ctwc - Unionville SystemCT0520011 | 14,693 | Surface water purchased | No current violation flagged |
| Aquarion-Simsbury RegionalCT1280021 | 14,691 | Ground water | No current violation flagged |
| Cromwell Fire District Water DepartmentCT0330011 | 14,316 | Ground water | No current violation flagged |
| Aquarion-New Milford RegionalCT0960011 | 13,331 | Ground water | No current violation flagged |
| Aquarion-ValleyCT1240011 | 13,080 | Surface water purchased | No current violation flagged |
| Avon Water CoCT0040011 | 11,590 | Ground water | Current monitoring/reporting flag |
| Aquarion-MysticCT1370011 | 10,788 | Surface water | No current violation flagged |
| Aquarion-New CanaanCT0900011 | 10,097 | Surface water purchased | No current violation flagged |
| Watertown Water & Sewer AuthorityCT1530021 | 9,972 | Surface water purchased | No current violation flagged |
| Bethel Water DeptCT0090011 | 9,507 | Surface water | No current violation flagged |
| Winsted Water WorksCT1620011 | 7,784 | Surface water | No current violation flagged |
| Kensington Fire DistrictCT0070011 | 7,553 | Surface water purchased | No current violation flagged |
| Aquarion-RidgefieldCT1180011 | 7,476 | Surface water purchased | No current violation flagged |
| Heritage Water CompanyCT1300021 | 7,300 | Surface water purchased | No current violation flagged |
| Putnam Water Pollution Control AuthorityCT1160011 | 7,300 | Surface water | No current violation flagged |
| Jewett City Water CompanyCT0580011 | 6,840 | Surface water | No current violation flagged |
| Watertown Fire DistrictCT1530011 | 6,718 | Ground water | Current monitoring/reporting flag |
| Ctwc - Crystal SystemCT0690011 | 6,378 | Ground water | No current violation flagged |
| Ctwc - Naugatuck Reg-Collinsville SysCT0230011 | 6,324 | Surface water | No current violation flagged |
| Aquarion-Newtown RegionalCT0970011 | 6,054 | Ground water | Other current violation flag |
| Ctwc - Naugatuck Reg-Terryville SystemCT1110011 | 5,607 | Ground water | No current violation flagged |
| Berlin Water Control CommissionCT0070021 | 5,128 | Surface water purchased | Current health-based flag |
| Ctwc - Shoreline Region-Chester SystemCT0261031 | 5,030 | Surface water | No current violation flagged |
| Portland Water DepartmentCT1130011 | 5,010 | Surface water purchased | No current violation flagged |
| Colchester Sewer & Water CommissionCT0280011 | 4,020 | Ground water | No current violation flagged |
| Ctwc - Naugatuck Reg-Thomaston SystemCT1400011 | 3,789 | Ground water | No current violation flagged |
| Ctwc - Shoreline Region-Sound ViewCT1050732 | 3,397 | Ground water | No current violation flagged |
| Ledyard Wpca - Ledyard CenterCT0727091 | 3,294 | Surface water purchased | Other current violation flag |
| Aquarion-Litchfield RegionalCT0740011 | 3,097 | Surface water purchased | No current violation flagged |
| Connecticut Valley HospitalCT0830021 | 2,928 | Surface water | No current violation flagged |
| Worthington Fire DistrictCT0070031 | 2,875 | Surface water purchased | No current violation flagged |
| Fairfield HillsCT0970021 | 2,610 | Ground water | Current health-based flag |
| Scwa, Montville Division (Mtv)CT0860011 | 2,570 | Ground water | No current violation flagged |
| Scwa, Tower-Ferry View DivisionCT0720041 | 2,567 | Ground water | Other current violation flag |
| Wolcott Water DepartmentCT1661423 | 2,550 | Surface water purchased | No current violation flagged |
| Ctwc - Gallup SystemCT1090031 | 2,538 | Ground water | No current violation flagged |
02 / CITY REPORTS
Connecticut city water-system reports
Connecticut has 107 city reports meeting the publication threshold for covered systems or reported population served.
Berlin7 systemsFarmington5 systemsNew Canaan5 systemsSouthington5 systemsStamford5 systemsDarien4 systemsLedyard4 systemsMiddletown4 systemsNewington4 systemsNorwalk4 systemsPlainville4 systemsWaterbury4 systemsWolcott4 systemsAvon3 systemsBeacon Falls3 systemsBristol3 systemsCheshire3 systemsCromwell3 systemsEast Granby3 systemsGreenwich3 systemsManchester3 systemsMansfield3 systemsMiddlebury3 systemsMontville3 systemsNewtown3 systemsPlymouth3 systemsProspect3 systemsRidgefield3 systemsSeymour3 systemsSouth Windsor3 systemsWallingford3 systemsWatertown3 systemsWilton3 systemsAnsonia2 systemsBethany2 systemsBethel2 systemsBrookfield2 systemsBurlington2 systemsDanbury2 systemsEast Windsor2 systemsEnfield2 systemsGlastonbury2 systemsGroton2 systemsLisbon2 systemsLitchfield2 systemsMeriden2 systemsNew Britain2 systemsNew Hartford2 systemsNew London2 systemsNorth Haven2 systemsOxford2 systemsPortland2 systemsSimsbury2 systemsTorrington2 systemsVernon2 systemsWaterford2 systemsWest Hartford2 systemsWestport2 systemsWindsor Locks2 systemsWoodbridge2 systemsBloomfield1 systemsBozrah1 systemsBranford1 systemsBridgeport1 systemsClinton1 systemsDerby1 systemsEast Hartford1 systemsEast Haven1 systemsEast Lyme1 systemsEaston1 systemsEllington1 systemsFairfield1 systemsFranklin1 systemsGranby1 systemsGuilford1 systemsHamden1 systemsHartford1 systemsHarwinton1 systemsLebanon1 systemsMadison1 systemsMiddlefield1 systemsMilford1 systemsMonroe1 systemsNaugatuck1 systemsNew Haven1 systemsNew Milford1 systemsNorth Branford1 systemsNorwich1 systemsOld Saybrook1 systemsOrange1 systemsPreston1 systemsRedding1 systemsRocky Hill1 systemsShelton1 systemsSomers1 systemsStafford1 systemsStonington1 systemsStratford1 systemsSuffield1 systemsTolland1 systemsTrumbull1 systemsWest Haven1 systemsWestbrook1 systemsWeston1 systemsWethersfield1 systemsWindham1 systemsWindsor1 systems
03 / COUNTY REPORTS
Connecticut county water-system reports
Connecticut has 8 county reports meeting the publication threshold for covered systems or reported population served.