Connecticut Water Quality — 158 Cities Tested

Analysis

Connecticut water quality overview

Connecticut's drinking water quality is below average overall, with an average score of 58.8 out of 100 across 158 cities tested. The median score is 56.6, serving a total population of 28,377,463 residents. 47% of cities scored a D or F, pointing to significant water quality challenges in parts of the state. PFAS "forever chemicals" were detected in 102 of 158 cities tested (65%). 94 cities exceed the 2024 EPA maximum contaminant levels. 3 cities have lead levels exceeding the EPA action level of 15 ppb, often indicating aging infrastructure with lead service lines or lead solder. The state relies on a mix of water sources: 38 cities use groundwater while 120 draw from surface water such as rivers, lakes, and reservoirs.

Key Concerns

Issues to watch in Connecticut

102 cities

PFAS Detected

65% of tested cities have PFAS in their water supply.

3 cities

Lead Exceedances

Lead levels above the EPA action level of 15 ppb (90th percentile).

134 cities

Health Violations

43,448 total violations recorded, 158 with unresolved issues.

42 cities

Failing Systems

Received a grade of F, indicating serious water quality issues.

Contaminant Data

Explore contaminants in Connecticut

Lead in Connecticut → Ranked by 90th percentile level (ppb) PFAS in Connecticut → Ranked by compounds detected Copper in Connecticut → Ranked by 90th percentile level (mg/L)

More contaminants tested in Connecticut

HAA5 → Chromium-6 → Arsenic → Nitrate → Strontium → 1,4-Dioxane → Manganese → Vanadium → Chlorate → Molybdenum → Cobalt → Lithium → NDMA →

State context

13

Superfund sites in Connecticut

EPA National Priorities List

90.4%

of Connecticut residents on fluoridated water

CDC, 2020

1,945

lbs released to surface water

Top 10 TRI facilities, 2023

1.2%

of Connecticut domestic wells exceed EPA arsenic limit

USGS, 83 samples · 10 µg/L MCL

Domestic well chemistry

Private-well water in Connecticut

Based on USGS Powell Domestic-Well Database — 515 private wells sampled across Connecticut. These wells are not regulated by the EPA; if you draw your tap from a private well, the public-system grade above does not apply to you.

0.2 µg/L

Median arsenic in domestic wells

P90 1.9 µg/L · max 11.0 µg/L

7 µg/L

Median manganese in domestic wells

13.6% exceed 300 µg/L aesthetic limit

Industrial pollution

Top industrial water polluters in Connecticut

Industrial polluters nearby

The 10 facilities reporting the most pounds released to surface water in Connecticut, 2023.

Total reported releases to surface water: 1,945 lbs

Facility	Top chemical	To surface water (lbs/yr)
ALLNEX USA INC. WALLINGFORD CT SITE Chemicals · ALLNEX USA INC WALLINGFORD, CT06492	Methanol	1,044
TRADEBE TREATMENT & RECYCLING OF BRIDGEPORT LLC Hazardous Waste · TRADEBE ENVIRONMENTAL SERVICES LLC BRIDGEPORT, CT06610	Nitrate compounds (water dissociable; reportable only when in aqueous solution)	252
MIDDLETOWN POWER LLC Electric Utilities · ARCLIGHT ENERGY PARTNERS MIDDLETOWN, CT06457	Ammonia	125
HAR-CONN CHROME CO Fabricated Metals · NA WEST HARTFORD, CT06110	Nitrate compounds (water dissociable; reportable only when in aqueous solution)	106
AHLSTROM NONWOVENS LLC Textiles · AHLSTROM USA INC WINDSOR LOCKS, CT06096	Ammonia	103

+ 5 more facilities

Source: EPA Toxic Release Inventory (TRI) 2023

Test your own tap

Get your Connecticut water tested

City-level data shows the source and infrastructure picture — but lead and other home-plumbing issues only show up at your tap. Find a state-certified lab, see what to test for, and what it costs.

Grade Distribution

How Connecticut cities scored

A: 11 B: 33 C: 39 D: 33 F: 42

Best Cities

Worst Cities

City Map

Water quality across Connecticut

Each dot is a city, colored by its water quality grade. Size reflects population served. Click any city to view its full water report.

All Cities

158 cities in Connecticut

Full rankings →

#	City	Grade	Score	Population	Violations
1	Plymouth	A+	95.6	4K	43
2	Uncasville	A	92.2	32K	3
3	Beacon Falls	A	92.1	23K	10
4	Sheffield	A	91.2	987	5
5	Barkhamsted	A-	89.7	8K	61
6	Sheffield	A-	89.3	1K	13
7	Berlin	A-	87	391K	3
8	Berlin	A-	87	391K	3
9	Berlin	A-	87	391K	3
10	Berlin	A-	87	391K	3
11	Norfolk	A-	86.3	913	10
12	Harwinton	B+	84.7	41K	51
13	Ansonia	B+	84.4	419K	32
14	Ansonia	B+	84.4	419K	32
15	Ansonia	B+	84.4	419K	32
16	Ansonia	B+	84.4	419K	32
17	Ansonia	B+	84.4	419K	32
18	Ansonia	B+	84.4	419K	32
19	Salisbury	B+	84.2	3K	43
20	North Canaan	B+	83.9	1K	7
21	Berlin	B+	83.6	464K	21
22	Lewisboro (T)	B+	83.6	656	104
23	Sprague	B+	83.4	1K	60
24	Ansonia	B+	82.4	432K	41
25	Ansonia	B+	82.4	432K	41
26	Windham	B+	80.8	22K	50
27	Berlin	B+	80.2	442K	18
28	Ansonia	B+	80.2	420K	45
29	Ansonia	B+	80.2	420K	45
30	Hampton	B	78.9	34K	11
31	Franklin	B	78.8	36K	29
32	Franklin	B	78.8	36K	29
33	Mashantucket	B	78	26K	47
34	Berlin	B	77	391K	11
35	East Granby	B	75.4	101K	203
36	Ansonia	B-	74.8	21K	35
37	Berlin	B-	74.6	446K	97
38	Groton	B-	74.5	12K	88
39	Clinton	B-	74.3	34K	288
40	Chester	B-	73.9	5K	115
41	Berlin	B-	73.8	492K	206
42	Berlin	B-	73.2	81K	55
43	Franklin	B-	70.5	37K	72
44	Hampton	B-	70.3	35K	43
45	Plainville	C+	69.6	33K	214
46	East Granby	C+	69.4	102K	258
47	Ansonia	C+	68.8	477K	85
48	Clinton	C+	68.5	35K	337
49	New London	C+	68.2	44K	158
50	Ansonia	C+	68.1	549K	126
51	Bristol	C+	67.9	85K	158
52	East Windsor	C+	67	21K	212
53	Clinton	C+	66.2	34K	347
54	East Granby	C+	66	17K	106
55	Middlebury	C	64.8	143K	124
56	Barkhamsted	C	64.7	8K	218
57	Carroll	C	64.5	1K	62
58	Chester	C	64.1	5K	276
59	Carroll	C	64	2K	64
60	Berlin	C	63.4	159K	176
61	North Stonington	C	63.2	2K	267
62	Bristol	C	63.1	62K	363
63	Berlin	C	62.5	396K	262
64	Goshen	C	62.3	4K	72
65	Bristol	C	62.1	59K	245
66	Berlin	C	60.9	544K	228
67	Berlin	C	60.5	544K	236
68	East Lyme	C	60.2	15K	219
69	Avon	C	60.1	6K	122
70	Ansonia	C-	60	456K	127
71	East Granby	C-	59.6	102K	265
72	Beacon Falls	C-	59	352K	155
73	Beacon Falls	C-	59	352K	155
74	Beacon Falls	C-	59	352K	155
75	Beacon Falls	C-	59	352K	155
76	Beacon Falls	C-	59	352K	155
77	Beacon Falls	C-	57.9	392K	158
78	Beacon Falls	C-	57.8	388K	172
79	East Granby	C-	57.8	153K	315
80	Killingly	C-	56.6	8K	172
81	Killingworth	C-	55.8	837	162
82	Middlebury	C-	55.4	125K	154
83	New London	C-	55	46K	307
84	Ansonia	D+	54.8	432K	92
85	Berlin	D+	54.4	509K	243
86	Clinton	D+	52.5	34K	567
87	Groton	D+	52.2	50K	123
88	Franklin	D+	52	37K	132
89	Middlebury	D+	50	125K	173
90	Brookfield	D+	50	5K	791
91	Woodbury	D+	50	3K	600
92	Ansonia	D	49.4	784K	200
93	Durham	D	49	3K	664
94	East Granby	D	48.8	122K	428
95	Beacon Falls	D	48.2	434K	234
96	Ansonia	D	48	515K	180
97	Harwinton	D	48	38K	784
98	Lower Sipaulovi, Lower Mishongnovi	D	48	609	293
99	Lower Sipaulovi, Lower Mishongnovi	D	48	609	293
100	Berlin	D	47.9	477K	259
101	Chester	D	47.7	5K	231
102	Beacon Falls	D	47.5	453K	237
103	Putnam	D	47.4	8K	179
104	Bow	D	47.4	808	112
105	Ashford	D	47	1K	588
106	Pomfret	D	47	850	443
107	East Haddam	D	47	673	306
108	Cromwell	D	46.8	54K	302
109	Clinton	D	46.8	35K	482
110	Kent	D	46.7	2K	242
111	Old Lyme	D	46	5K	778
112	Plainfield	D	46	5K	448
113	East Hampton	D	46	3K	889
114	Marlborough	D	46	2K	312
115	Beacon Falls	D	45.4	463K	245
116	Colchester	D	45	6K	663
117	Cromwell	F	44.8	41K	257
118	Berlin	F	44.4	391K	262
119	Middlebury	F	44	9K	436
120	Bethel	F	43	72K	313
121	Hebron	F	43	3K	376
122	Willington	F	43	2K	370
123	Beacon Falls	F	42.6	352K	229
124	Beacon Falls	F	42.5	532K	269
125	Griswold	F	42.4	8K	361
126	Bethel	F	42	79K	1590
127	Sharon	F	42	865	154
128	Franklin	F	41.9	38K	457
129	Beacon Falls	F	41.6	352K	1850
130	Beacon Falls	F	41.6	352K	429
131	Beacon Falls	F	41.5	553K	232
132	Groton	F	41.5	48K	305
133	Berlin	F	41	553K	419
134	Washington	F	41	1K	335
135	Hopkinton	F	41	769	266
136	Harwinton	F	40.4	41K	340
137	Putnam	F	40	9K	735
138	Berlin	F	39.9	508K	524
139	Beacon Falls	F	39.8	423K	500
140	East Granby	F	39.6	120K	573
141	Harwinton	F	39.4	46K	212
142	Coventry	F	39	3K	235
143	Ansonia	F	38.7	419K	234
144	Brookfield	F	38.5	17K	998
145	East Granby	F	38.4	28K	436
146	Killingly	F	37.5	8K	407
147	Beacon Falls	F	36.6	525K	257
148	East Granby	F	36.4	103K	324
149	Franklin	F	35.9	62K	1243
150	Beacon Falls	F	35.6	361K	484
151	Beacon Falls	F	35.6	352K	285
152	Bethel	F	35	74K	860
153	Putnam	F	35	8K	748
154	Ansonia	F	34.5	573K	663
155	Ansonia	F	34.5	520K	577
156	Franklin	F	33.8	43K	278
157	Ansonia	F	33.5	591K	555
158	East Granby	F	33.4	153K	811

Counties

Browse Connecticut counties

Berkshire 2 cities · avg 90.3 Coos 2 cities · avg 64.3 Fairfield 24 cities · avg 46.6 Hartford 36 cities · avg 62.4 Litchfield 15 cities · avg 63.9 Merrimack 1 city · avg 47.4 Middlesex 9 cities · avg 52.8 New Haven 31 cities · avg 64.9 New London 18 cities · avg 56.8 Rockingham 2 cities · avg 74.6 Tolland 3 cities · avg 41.7 Washington 1 city · avg 41 Westchester 1 city · avg 83.6 Windham 9 cities · avg 48.6

ZIP Codes

Browse Connecticut by ZIP code

Look up water quality by ZIP code to find the systems serving your area.

View all Connecticut ZIP codes →

FAQ

Frequently asked questions about Connecticut's water

Is Connecticut's tap water safe to drink?

Connecticut's water quality varies by city. The statewide average grade is C- (58.8/100). 28% of cities scored an A or B, while 47% received a D or F. Check your specific city for detailed results.

Which Connecticut cities have the best water quality?

The top-rated cities are Plymouth (A+), Uncasville (A), Beacon Falls (A). These cities scored highest based on violation history, lead levels, PFAS contamination, and regulatory compliance.

Which Connecticut cities have the worst water quality?

The lowest-rated cities are East Granby (F), Ansonia (F), Franklin (F). We recommend residents in these areas consider water filtration and review their city's specific contaminant data.

How many Connecticut cities have PFAS in their water?

102 out of 158 cities tested positive for PFAS "forever chemicals" (65%). 94 cities exceed the 2024 EPA maximum contaminant levels. Reverse osmosis or activated carbon filters can help reduce PFAS exposure.

Do any Connecticut cities have dangerous lead levels?

3 cities exceed the EPA lead action level of 15 ppb. Lead contamination typically comes from aging pipes and lead service lines rather than the water source itself. An NSF 53-certified filter can effectively remove lead from tap water.

Connecticut Water Quality Report