Connecticut Water Quality — 129 Cities Tested

Latest water news in Connecticut

Recent reporting on Connecticut drinking water — boil-water advisories, regulatory action, and infrastructure events.

Jun 5, 2026

Lead-Pipe Progress: Connecticut Gets $27.4M as Fairfax Water Nears the Finish Line

Connecticut wins $27.4M to replace up to 8,000 lead service lines as Fairfax Water nears zero ahead of the November 2027 federal deadline.

Read full story →

Analysis

Connecticut water quality overview

Connecticut's drinking water quality is fair overall, with an average score of 60.8 out of 100 across 129 cities tested. The median score is 59, serving a total population of 16,503,997 residents. 42% of cities scored a D or F, pointing to significant water quality challenges in parts of the state. PFAS "forever chemicals" were detected in 86 of 129 cities tested (67%). 79 cities exceed the 2024 EPA maximum contaminant levels. 2 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: 40 cities use groundwater while 89 draw from surface water such as rivers, lakes, and reservoirs.

Key Concerns

Issues to watch in Connecticut

86 cities

PFAS Detected

67% of tested cities have PFAS in their water supply.

2 cities

Lead Exceedances

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

105 cities

Health Violations

33,753 total violations recorded, 129 with unresolved issues.

27 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: 15 B: 25 C: 35 D: 27 F: 27

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

129 cities in Connecticut

Full rankings →

#	City	Grade	Score	Population	Violations
1	Thomaston	A+	95.1	4K	43
2	Uncasville	A	92.2	32K	3
3	Sheffield	A	91.2	987	5
4	Naugatuck	A	90.8	23K	10
5	Winchester	A-	89.7	8K	61
6	Windsor	A-	87	391K	3
7	East Hartford	A-	86.7	391K	3
8	Hartford	A-	86.7	391K	3
9	Wethersfield	A-	86.7	391K	3
10	Norfolk	A-	86.3	913	10
11	Branford	A-	85.4	419K	32
12	East Haven	A-	85.4	419K	32
13	Hamden	A-	85.4	419K	32
14	New Haven	A-	85.4	419K	32
15	Salisbury	A-	85.2	520	43
16	West Haven	B+	84.9	419K	32
17	Milford	B+	84.6	419K	32
18	Torrington	B+	84.2	38K	51
19	North Canaan	B+	83.9	1K	7
20	Lewisboro (T)	B+	83.6	630	104
21	Woodbridge	B+	83.4	419K	41
22	Sprague	B+	83.4	1K	60
23	West Hartford	B+	83.3	391K	21
24	Ansonia	B+	82.4	419K	41
25	Orange	B+	80.4	419K	45
26	Derby	B+	80.2	419K	45
27	Glastonbury	B+	80.2	391K	18
28	Hampton	B	78.9	34K	11
29	Bozrah	B	78.8	36K	29
30	Franklin	B	78.8	36K	29
31	Mashantucket	B	78	26K	47
32	Rocky Hill	B	77	391K	11
33	Oxford	B	75.8	13K	35
34	Cromwell	B	75.6	14K	97
35	Ellington	B	75.4	101K	203
36	Stonington	B	75	11K	88
37	Old Saybrook	B-	74.3	34K	288
38	Windsor Locks	B-	73.6	391K	206
39	New Britain	B-	72.4	74K	55
40	Norwich	B-	70.5	36K	72
41	Avon	C+	69.6	15K	214
42	Suffield	C+	69.4	101K	258
43	Prospect	C+	69.1	419K	126
44	Madison	C+	68.5	34K	337
45	Meriden	C+	68.3	58K	85
46	New London	C+	68.2	28K	158
47	Bristol	C+	67.9	52K	158
48	Somers	C+	66.5	19K	212
49	Westbrook	C+	66.2	34K	347
50	Granby	C+	66	2K	106
51	Barkhamsted	C	64.7	8K	218
52	Carroll	C	64.5	1K	62
53	Plymouth	C	64.1	52K	363
54	Deep River	C	64.1	5K	276
55	Carroll	C	64	1K	64
56	Waterbury	C	63.8	107K	124
57	Plainville	C	63.4	74K	176
58	North Stonington	C	63.2	2K	267
59	Portland	C	61.7	5K	262
60	Stafford	C	60.6	679	265
61	South Windsor	C	60.5	391K	236
62	Manchester	C	60.4	51K	228
63	East Lyme	C	60.2	15K	219
64	North Haven	C-	60	419K	127
65	Fairfield	C-	59	352K	155
66	Redding	C-	59	352K	155
67	Stratford	C-	59	352K	155
68	Bridgeport	C-	58.3	352K	155
69	Shelton	C-	58.3	352K	155
70	Westport	C-	57.9	352K	158
71	Beacon Falls	C-	57.8	352K	172
72	Bethany	C-	55.8	419K	92
73	Killingworth	C-	55.8	750	162
74	Brooklyn	C-	55.6	6K	172
75	Waterford	C-	55	44K	307
76	Farmington	D+	54.4	391K	243
77	Ledyard	D+	52.8	6K	123
78	Clinton	D+	52.5	34K	567
79	Preston	D+	52	36K	132
80	Seymour	D+	50.4	419K	200
81	Watertown	D+	50	7K	173
82	Woodbury	D+	50	1K	600
83	New Fairfield	D+	50	880	791
84	Enfield	D	49.8	19K	428
85	Wallingford	D	49	37K	180
86	Durham	D	49	2K	664
87	Wilton	D	48.2	42K	234
88	Harwinton	D	48	38K	784
89	Lower Sipaulovi, Lower Mishongnovi	D	48	609	293
90	Lower Sipaulovi, Lower Mishongnovi	D	48	609	293
91	Putnam	D	47.4	8K	179
92	Newington	D	47.1	391K	259
93	Norwalk	D	47	40K	237
94	Pomfret	D	47	748	443
95	Guilford	D	46.8	34K	482
96	Kent	D	46.7	1K	242
97	Middletown	D	46	44K	302
98	Plainfield	D	46	3K	448
99	East Hampton	D	46	2K	889
100	Old Lyme	D	46	541	778
101	Colchester	D	45	4K	663
102	Southbury	D	45	856	436
103	New Canaan	F	44.9	352K	245
104	Bethel	F	43	10K	313
105	Hebron	F	43	2K	376
106	Brookfield	F	43	1K	1590
107	Willington	F	43	1K	370
108	Darien	F	42.5	352K	269
109	Griswold	F	42.4	7K	361
110	Sharon	F	42	865	154
111	Groton	F	41.5	33K	305
112	Stamford	F	41	352K	232
113	Berlin	F	41	8K	419
114	Washington	F	41	818	335
115	North Branford	F	39.7	419K	234
116	East Windsor	F	39.6	101K	573
117	New Milford	F	38.5	2K	998
118	Greenwich	F	37.6	567	257
119	Killingly	F	37.5	6K	407
120	Tolland	F	37.4	2K	324
121	Newtown	F	36.6	3K	484
122	Woodstock	F	36.5	900	748
123	Montville	F	35.9	36K	1243
124	Cheshire	F	35.5	419K	577
125	Wolcott	F	35.5	3K	663
126	Southington	F	34.5	43K	555
127	Danbury	F	34	64K	860
128	Lisbon	F	33.8	36K	278
129	Mansfield	F	33.4	21K	811

Counties

Browse Connecticut counties

Berkshire 1 city · avg 91.2 Coos 2 cities · avg 64.3 Fairfield 19 cities · avg 48.2 Hartford 29 cities · avg 65.4 Litchfield 12 cities · avg 68.1 Middlesex 5 cities · avg 52.2 New Haven 30 cities · avg 65.6 New London 17 cities · avg 57.8 Rockingham 1 city · avg 78.9 Tolland 2 cities · avg 43 Westchester 1 city · avg 83.6 Windham 6 cities · avg 45

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 (60.8/100). 31% of cities scored an A or B, while 42% 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 Thomaston (A+), Uncasville (A), Sheffield (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 Mansfield (F), Lisbon (F), Danbury (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?

86 out of 129 cities tested positive for PFAS "forever chemicals" (67%). 79 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?

2 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