2026 Rankings

Least Reliable Water Systems in Connecticut — 2026

Last updated: June 4, 2026

442 ZIP codes ranked by Reliability Score #1: ZIP 06241 (Dayville, CT) — 10/100
Lead Violations Lowest Score Safest Flood Risk Energy Cost Radon PFAS Reliability EJ Index Homebuyer Risk CO & Gas Safest Gas Remediation Burden Unresolved Violations (by Utility) Water Equity (by Utility)

Out of 442 ZIP codes with data in Connecticut, these are the lowest-ranked areas for reliability score. See also: National Least Reliable Water Systems in America | All Connecticut Rankings

Statistic Value
ZIP codes ranked 442
Lowest value 10/100
Median value 70/100
State Connecticut

100 Lowest-Ranked ZIP Codes

Rank ZIP Code City State Reliability Score Safety Score
1 06241 Dayville CT 10/100 41/100
2 06258 Pomfret CT 10/100 50/100
3 06279 Willington CT 10/100 66/100
4 06331 Canterbury CT 10/100 66/100
5 06281 Woodstock CT 15/100 46/100
6 06002 Bloomfield CT 20/100 69/100
7 06043 Bolton CT 20/100 67/100
8 06128 East Hartford CT 20/100 66/100
9 06138 East Hartford CT 20/100 66/100
10 06234 Brooklyn CT 20/100 68/100
11 06084 Tolland CT 25/100 70/100
12 06371 Old Lyme CT 25/100 40/100
13 06026 East Granby CT 26/100 83/100
14 06278 Ashford CT 26/100 74/100
15 06353 Montville CT 28/100 60/100
16 06422 Durham CT 28/100 60/100
17 06420 Salem CT 29/100 62/100
18 06232 Andover CT 31/100 74/100
19 06260 Putnam CT 31/100 71/100
20 06776 New Milford CT 31/100 67/100
21 06763 Morris CT 32/100 74/100
22 06249 Lebanon CT 34/100 62/100
23 06357 Niantic CT 34/100 52/100
24 06426 Essex CT 34/100 52/100
25 06470 Newtown CT 34/100 57/100
26 06756 Goshen CT 35/100 69/100
27 06335 Gales Ferry CT 36/100 56/100
28 06792 Torrington CT 36/100 76/100
29 06408 Cheshire CT 37/100 50/100
30 06411 Cheshire CT 37/100 50/100
31 06415 Colchester CT 37/100 66/100
32 06417 Deep River CT 37/100 61/100
33 06757 Kent CT 37/100 74/100
34 06088 East Windsor CT 39/100 82/100
35 06492 Wallingford CT 39/100 55/100
36 06493 Wallingford CT 39/100 60/100
37 06494 Wallingford CT 39/100 60/100
38 06495 Wallingford CT 39/100 60/100
39 06108 East Hartford CT 40/100 65/100
40 06118 East Hartford CT 40/100 60/100
41 06037 Berlin CT 42/100 81/100
42 06074 South Windsor CT 42/100 78/100
43 06370 Oakdale CT 42/100 66/100
44 06712 Prospect CT 42/100 66/100
45 06235 Chaplin CT 44/100 54/100
46 06277 Thompson CT 44/100 74/100
47 06365 Preston CT 44/100 64/100
48 06374 Plainfield CT 44/100 74/100
49 06419 Killingworth CT 44/100 65/100
50 06030 Farmington CT 45/100 91/100
51 06034 Farmington CT 45/100 94/100
52 06075 Stafford CT 45/100 66/100
53 06057 New Hartford CT 47/100 74/100
54 06069 Sharon CT 47/100 74/100
55 06259 Pomfret Center CT 47/100 78/100
56 06414 Cobalt CT 47/100 41/100
57 06424 East Hampton CT 47/100 61/100
58 06450 Meriden CT 47/100 56/100
59 06451 Meriden CT 47/100 56/100
60 06454 Meriden CT 47/100 61/100
61 06455 Middlefield CT 47/100 66/100
62 06481 Rockfall CT 47/100 54/100
63 06798 Woodbury CT 47/100 74/100
64 06801 Bethel CT 47/100 59/100
65 06828 Fairfield CT 47/100 61/100
66 06070 Simsbury CT 49/100 80/100
67 06412 Chester CT 49/100 54/100
68 06447 Marlborough CT 50/100 91/100
69 06488 Southbury CT 50/100 51/100
70 06033 Glastonbury CT 51/100 81/100
71 06238 Coventry CT 51/100 76/100
72 06790 Torrington CT 51/100 72/100
73 06082 Enfield CT 52/100 81/100
74 06083 Enfield CT 52/100 94/100
75 06480 Portland CT 52/100 56/100
76 06716 Wolcott CT 52/100 61/100
77 06785 South Kent CT 52/100 78/100
78 06795 Watertown CT 52/100 74/100
79 06904 Stamford CT 52/100 69/100
80 06910 Stamford CT 52/100 65/100
81 06911 Stamford CT 52/100 65/100
82 06912 Stamford CT 52/100 65/100
83 06913 Stamford CT 52/100 65/100
84 06914 Stamford CT 52/100 65/100
85 06920 Stamford CT 52/100 65/100
86 06921 Stamford CT 52/100 65/100
87 06922 Stamford CT 52/100 65/100
88 06925 Stamford CT 52/100 65/100
89 06926 Stamford CT 52/100 65/100
90 06927 Stamford CT 52/100 65/100
91 06928 Stamford CT 52/100 65/100
92 06438 Haddam CT 53/100 63/100
93 06016 Broad Brook CT 54/100 87/100
94 06471 North Branford CT 54/100 55/100
95 06131 Newington CT 55/100 97/100
96 06611 Trumbull CT 55/100 57/100
97 06793 Washington CT 55/100 76/100
98 06360 Norwich CT 56/100 49/100
99 06032 Farmington CT 57/100 81/100
100 06076 Stafford Springs CT 57/100 61/100

Methodology

Water system reliability scores (0-100) combine violation frequency, violation recency, resolution rate, and system size. Systems with repeated health-based violations and unresolved issues score lowest. The reliability score focuses specifically on the water utility performance, distinct from the broader Home Safety Score.

Data sources: EPA Safe Drinking Water Information System (SDWIS), FEMA National Flood Insurance Program, EPA radon zone maps, EIA electricity rates, and Consumer Confidence Reports. Last updated: 2026-06-04.

Frequently Asked Questions

What does a low water reliability score mean?

A low reliability score (below 50) indicates a water system with frequent violations, poor resolution rates, or recurring compliance issues. These systems may have aging infrastructure, inadequate treatment, or management challenges.

How is reliability different from safety score?

The reliability score focuses specifically on the water utility performance (violations, resolution, compliance). The Home Safety Score is broader, also including lead risk, radon, and flood data. A ZIP code can have a reliable water system but still have high radon or flood risk.

Explore More Rankings

How this ranking is calculated, data sources, and limitations: Rankings Methodology →

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Disclaimer: Rankings are based on EPA, FEMA, and federal agency data. They reflect historical patterns and risk indicators, not necessarily current conditions. For the most current information, contact your local water utility or request a Consumer Confidence Report.

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