Connecticut tap water quality

476 active community water systems.

Largest water systems

GradeSystemPeopleHealth violations (5y)
CRegional Water Authority (South Central Connecticut)418,9000
AThe Metropolitan District (MDC Hartford)390,8870
CAquarion Water Company (Eastern Fairfield County)351,7560
AAquarion-Stamford119,2140
AWaterbury Water Department107,2710
CCtwc - Northern Reg-Western System101,3130
ANew Britain Water Department73,5340
BDanbury Water Department62,0550
CMeriden Water Division58,4410
BAquarion-Greenwich53,2970
BBristol Water Department52,0790
CManchester Water Department51,1980
DSouthington Water Department43,0690
ASouth Norwalk Electric & Water42,0000
AMiddletown Water Department41,0190
CNorwalk First Taxing District40,2560
ATorrington Water Company37,9150
CWallingford Water Department37,2670
DNorwich Public Utilities36,1630
CCtwc - Shoreline Region-Guilford System33,9750
AMohegan Tribal Utility Authority31,9610
AGroton Utilities30,2000
ANew London Dept. of Public Utilities27,6200
BUniversity of Connecticut - Main Campus27,1990
ACtwc - Naugatuck Region-Central System22,7350
BMashantucket Pequot Water System22,1710
AWindham Water Works21,2140
AAquarion-Darien18,7370
CHazardville Water Company18,5440
DAquarion-Plainville Regional18,2311
AWaterford Wpca16,5780
CEast Lyme Water & Sewer Commission15,2450
DCtwc - Unionville System14,6931
AAquarion-Simsbury Regional14,6910
ACromwell Fire District Water Department14,3160
CAquarion-New Milford Regional13,3310
BAquarion-Valley13,0800
CAvon Water Co11,5900
AAquarion-Mystic10,7880
AAquarion-New Canaan10,0970
BWatertown Water & Sewer Authority9,9720
CBethel Water Dept9,5070
AWinsted Water Works7,7840
BKensington Fire District7,5530
CAquarion-Ridgefield7,4760
AHeritage Water Company7,3000
CPutnam Water Pollution Control Authority7,3000
BJewett City Water Company6,8400
AWatertown Fire District6,7180
CCtwc - Crystal System6,3780

Most issues (systems serving 10,000+)

D

Southington Water Department

Serves 43,069 people · Surface water · Full report →
No health-based violations in the last 5 years; 12 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOS, PFOA; Lead 90th percentile below the action level (2024).
D

Norwich Public Utilities

Serves 36,163 people · Surface water · Full report →
No health-based violations in the last 5 years; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Other PFAS above 2024 limits (rule proposed for repeal): PFHxS, Hazard Index; Lead 90th percentile below the action level (2025).
D

Aquarion-Plainville Regional

Serves 18,231 people · Groundwater · Full report →
1 health-based violation in the last 5 years; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2025).
D

Ctwc - Unionville System

Serves 14,693 people · Surface water · Full report →
1 health-based violation in the last 5 years; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2025).
C

Meriden Water Division

Serves 58,441 people · Surface water · Full report →
No health-based violations in the last 5 years; 7 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2026).
C

Manchester Water Department

Serves 51,198 people · Surface water · Full report →
No health-based violations in the last 5 years; 3 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2025).
C

East Lyme Water & Sewer Commission

Serves 15,245 people · Surface water · Full report →
No health-based violations in the last 5 years; 2 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOS, PFOA; Lead 90th percentile below the action level (2026).
C

Ctwc - Northern Reg-Western System

Serves 101,313 people · Surface water · Full report →
No health-based violations in the last 5 years; 1 monitoring/reporting violation; PFOA/PFOS average above the 4 ppt federal limit: PFOS, PFOA; Lead 90th percentile below the action level (2026).
C

Norwalk First Taxing District

Serves 40,256 people · Surface water · Full report →
No health-based violations in the last 5 years; 1 monitoring/reporting violation; PFOA/PFOS average above the 4 ppt federal limit: PFOS, PFOA; Lead 90th percentile below the action level (2025).
C

Hazardville Water Company

Serves 18,544 people · Groundwater · Full report →
No health-based violations in the last 5 years; 1 monitoring/reporting violation; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2024).
C

Regional Water Authority (South Central Connecticut)

Serves 418,900 people · Surface water · Full report →
No health-based violations in the last 5 years; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2025).
C

Aquarion Water Company (Eastern Fairfield County)

Serves 351,756 people · Surface water · Full report →
No health-based violations in the last 5 years; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2025).
C

Ctwc - Shoreline Region-Guilford System

Serves 33,975 people · Surface water · Full report →
No health-based violations in the last 5 years; PFOA/PFOS average above the 4 ppt federal limit: PFOS, PFOA; Lead 90th percentile below the action level (2025).
C

Avon Water Co

Serves 11,590 people · Groundwater · Full report →
No health-based violations in the last 5 years; PFOA/PFOS average above the 4 ppt federal limit: PFOA, PFOS; Lead 90th percentile below the action level (2026).
C

Wallingford Water Department

Serves 37,267 people · Surface water · Full report →
No health-based violations in the last 5 years; 22 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOS; Lead 90th percentile below the action level (2025).
C

Aquarion-New Milford Regional

Serves 13,331 people · Groundwater · Full report →
No health-based violations in the last 5 years; 46 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOA; Lead 90th percentile below the action level (2026).
B

Bristol Water Department

Serves 52,079 people · Surface water · Full report →
No health-based violations in the last 5 years; 2 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOA; Lead 90th percentile below the action level (2025).
B

Mashantucket Pequot Water System

Serves 22,171 people · Surface water · Full report →
No health-based violations in the last 5 years; 2 monitoring/reporting violations; PFOA/PFOS average above the 4 ppt federal limit: PFOA; Lead 90th percentile below the action level (2025).
B

Danbury Water Department

Serves 62,055 people · Surface water · Full report →
No health-based violations in the last 5 years; 1 monitoring/reporting violation; PFOA/PFOS average above the 4 ppt federal limit: PFOA; Lead 90th percentile below the action level (2025).
B

Aquarion-Greenwich

Serves 53,297 people · Surface water · Full report →
No health-based violations in the last 5 years; 1 monitoring/reporting violation; PFOA/PFOS average above the 4 ppt federal limit: PFOA; Lead 90th percentile below the action level (2025).

Cities

AmstonAndoverAnsoniaAshfordAvonBalticBantamBarkhamstedBeacon FallsBerlinBethanyBethelBethlehemBloomfieldBoltonBozrahBranfordBridgeportBridgewaterBristolBroad BrookBrookfieldBrooklynBurlingtonCanaanCanterburyCantonCanton CenterCenterbrookCentral VillageChaplinCheshireChesterClintonCobaltColchesterColumbiaCornwallCornwall BridgeCos CobCoventryCromwellDanburyDanielsonDarienDayvilleDeep RiverDerbyDurhamEast BerlinEast CanaanEast GranbyEast HaddamEast HamptonEast HartfordEast HavenEast LymeEast WindsorEastfordEastonEllingtonEnfieldEssexFairfieldFalls VillageFarmingtonFranklinGales FerryGaylordsvilleGilmanGlastonburyGoshenGranbyGreenwichGriswoldGrotonGuilfordHaddamHamdenHartfordHarwintonHebronIvorytonJewett CityKentKillinglyKillingworthLakevilleLebanonLedyardLisbonLitchfieldMadisonManchesterMansfieldMansfield CenterMarionMarlboroughMashantucketMeridenMiddle HaddamMiddleburyMiddlefieldMiddletownMilfordMilldaleMonroeMontvilleMoodusMoosupMorrisMysticNaugatuckNew BritainNew CanaanNew FairfieldNew HartfordNew HavenNew LondonNew MilfordNew Preston Marble DaleNewingtonNewtownNianticNorfolkNorth BranfordNorth CanaanNorth FranklinNorth GrosvenordaleNorth HavenNorth StoningtonNorth WindhamNorthfieldNorthfordNorwalkNorwichOakdaleOakvilleOld GreenwichOld LymeOld SaybrookOrangeOxfordPawcatuckPine MeadowPlainfieldPlainvillePlantsvillePlymouthPomfretPomfret CenterPortlandPrestonProspectPutnamQuaker HillQuinebaugReddingRidgefieldRiversideRivertonRockfallRocky HillRogersRoxburySalemSalisburySandy HookSeymourSharonSheltonShermanSimsburySomersSouth GlastonburySouth KentSouth LymeSouth WindhamSouth WindsorSouthburySouthingtonSouthportSpragueStaffordStamfordSterlingStoningtonStorrs MansfieldStratfordSuffieldTaftvilleTariffvilleTerryvilleThomastonThompsonTollandTorringtonTrumbullUncasvilleUnionvilleVernonVernon RockvilleVoluntownWallingfordWarrenWashingtonWashington DepotWaterburyWaterfordWatertownWaureganWeatogueWest CornwallWest HartfordWest HavenWest SimsburyWest SuffieldWestbrookWestonWestportWethersfieldWillimanticWillingtonWiltonWinchesterWindhamWindsorWindsor LocksWinstedWolcottWoodbridgeWoodburyWoodstockYantic