Connecticut Tap Water Quality Report
131 cities analyzed • 2,537,079 people served
Updated March 2026 • Data from EWG & EPA SDWIS
Most Common Contaminants in Connecticut
| Contaminant | Found In | % of Cities |
|---|---|---|
| Nitrate and nitrite carcinogen | 116 of 131 | 89% |
| Nitrate carcinogen | 115 of 131 | 88% |
| Barium | 111 of 131 | 85% |
| Total trihalomethanes (TTHMs) carcinogen | 90 of 131 | 69% |
| Bromodichloromethane carcinogen | 86 of 131 | 66% |
| Chloroform carcinogen | 86 of 131 | 66% |
| Haloacetic acids (HAA5) carcinogen | 86 of 131 | 66% |
| Dibromochloromethane carcinogen | 82 of 131 | 63% |
| Dichloroacetic acid carcinogen | 70 of 131 | 53% |
| Radium, combined (-226 and -228) | 68 of 131 | 52% |
City-by-City Water Quality Rankings
Ranked by number of contaminants above EWG health guidelines (most to fewest).
| # | City | Detected | Above Guidelines | Above Legal | People Served |
|---|---|---|---|---|---|
| 1 | Mansfield | 32 | 18 | 0 | 27,199 |
| 2 | Enfield | 30 | 18 | 0 | 18,544 |
| 3 | Simsbury | 28 | 18 | 0 | 14,691 |
| 4 | Somers | 31 | 18 | 0 | 352 |
| 5 | Southington | 34 | 17 | 0 | 43,069 |
| 6 | Avon | 28 | 17 | 0 | 11,590 |
| 7 | East Windsor | 31 | 16 | 0 | 98,690 |
| 8 | Manchester | 40 | 16 | 1 | 51,198 |
| 9 | Plainville | 30 | 16 | 0 | 18,231 |
| 10 | Farmington | 30 | 16 | 0 | 14,693 |
| 11 | New Haven | 31 | 15 | 0 | 418,900 |
| 12 | Meriden | 32 | 15 | 0 | 58,441 |
| 13 | Windham | 25 | 15 | 0 | 21,214 |
| 14 | Cromwell | 23 | 15 | 0 | 14,316 |
| 15 | Seymour | 31 | 15 | 0 | 13,080 |
| 16 | New Milford | 23 | 15 | 0 | 12,659 |
| 17 | Bethel | 22 | 15 | 1 | 9,507 |
| 18 | Newtown | 23 | 15 | 2 | 6,054 |
| 19 | Derby | 31 | 15 | 0 | 1,101 |
| 20 | Oxford | 31 | 15 | 0 | 120 |
| 21 | Bridgeport | 27 | 14 | 0 | 351,756 |
| 22 | Guilford | 29 | 14 | 0 | 33,975 |
| 23 | Greenwich | 21 | 13 | 0 | 53,297 |
| 24 | East Lyme | 26 | 13 | 0 | 15,245 |
| 25 | Putnam | 17 | 13 | 0 | 7,300 |
| 26 | Bristol | 21 | 12 | 0 | 52,079 |
| 27 | Wallingford | 19 | 12 | 0 | 37,267 |
| 28 | Naugatuck | 20 | 12 | 0 | 22,615 |
| 29 | Darien | 21 | 12 | 0 | 18,737 |
| 30 | Stonington | 20 | 12 | 0 | 10,788 |
| 31 | Chester | 19 | 12 | 0 | 5,030 |
| 32 | Wolcott | 28 | 12 | 0 | 2,550 |
| 33 | Ridgefield | 16 | 12 | 0 | 958 |
| 34 | Coventry | 15 | 12 | 0 | 501 |
| 35 | North Stonington | 15 | 12 | 0 | 370 |
| 36 | Middlebury | 20 | 12 | 0 | 120 |
| 37 | Cheshire | 16 | 12 | 0 | 84 |
| 38 | Shelton | 21 | 12 | 0 | 75 |
| 39 | Danbury | 20 | 11 | 0 | 62,055 |
| 40 | Middletown | 18 | 11 | 0 | 41,019 |
| 41 | Watertown | 28 | 11 | 0 | 9,972 |
| 42 | Plymouth | 12 | 11 | 0 | 5,607 |
| 43 | Hebron | 16 | 11 | 0 | 1,927 |
| 44 | Madison | 15 | 11 | 0 | 1,368 |
| 45 | Brookfield | 15 | 11 | 0 | 1,315 |
| 46 | Woodbury | 16 | 11 | 0 | 1,209 |
| 47 | Durham | 12 | 11 | 0 | 490 |
| 48 | Prospect | 12 | 11 | 0 | 465 |
| 49 | Sharon | 13 | 11 | 0 | 62 |
| 50 | North Canaan | 13 | 11 | 0 | 0 |
| 51 | Sherman | 14 | 11 | 0 | 0 |
| 52 | Stamford | 21 | 10 | 0 | 119,214 |
| 53 | New Britain | 21 | 10 | 0 | 73,534 |
| 54 | Torrington | 21 | 10 | 0 | 37,915 |
| 55 | Norwich | 21 | 10 | 0 | 36,163 |
| 56 | New Canaan | 17 | 10 | 0 | 10,097 |
| 57 | Berlin | 21 | 10 | 0 | 7,553 |
| 58 | Canton | 14 | 10 | 0 | 6,324 |
| 59 | Portland | 23 | 10 | 0 | 5,010 |
| 60 | Thomaston | 11 | 10 | 0 | 3,789 |
| 61 | Plainfield | 11 | 10 | 0 | 1,713 |
| 62 | Old Lyme | 13 | 10 | 0 | 1,068 |
| 63 | Kent | 13 | 10 | 0 | 817 |
| 64 | Salisbury | 11 | 10 | 0 | 520 |
| 65 | Pomfret | 14 | 10 | 0 | 300 |
| 66 | Norwalk | 21 | 9 | 0 | 42,000 |
| 67 | Montville | 11 | 9 | 0 | 2,570 |
| 68 | Southbury | 11 | 9 | 0 | 816 |
| 69 | Woodstock | 13 | 9 | 0 | 620 |
| 70 | Canaan | 9 | 9 | 0 | 248 |
| 71 | Lebanon | 11 | 9 | 0 | 172 |
| 72 | Bethany | 11 | 9 | 0 | 138 |
| 73 | Sterling | 12 | 9 | 0 | 0 |
| 74 | Hartford | 21 | 8 | 0 | 390,887 |
| 75 | Waterbury | 23 | 8 | 0 | 107,271 |
| 76 | Waterford | 14 | 8 | 0 | 16,578 |
| 77 | Griswold | 9 | 8 | 0 | 440 |
| 78 | Suffield | 12 | 8 | 0 | 0 |
| 79 | Sprague | 9 | 8 | 0 | 0 |
| 80 | Groton | 15 | 7 | 0 | 30,200 |
| 81 | New London | 14 | 7 | 0 | 27,620 |
| 82 | Winchester | 12 | 7 | 0 | 7,784 |
| 83 | Ledyard | 15 | 7 | 0 | 3,294 |
| 84 | East Haddam | 11 | 7 | 0 | 650 |
| 85 | Salem | 11 | 7 | 0 | 184 |
| 86 | Weston | 11 | 7 | 0 | 100 |
| 87 | Bethlehem | 11 | 7 | 0 | 72 |
| 88 | Marlborough | 11 | 6 | 0 | 1,348 |
| 89 | Norfolk | 11 | 6 | 0 | 913 |
| 90 | Goshen | 7 | 5 | 0 | 462 |
| 91 | Vernon | 9 | 5 | 0 | 430 |
| 92 | Washington | 6 | 5 | 0 | 398 |
| 93 | Warren | 6 | 5 | 0 | 0 |
| 94 | Preston | 6 | 4 | 0 | 550 |
| 95 | New Fairfield | 7 | 4 | 0 | 524 |
| 96 | Willington | 6 | 4 | 0 | 489 |
| 97 | Canterbury | 5 | 4 | 0 | 152 |
| 98 | Litchfield | 6 | 4 | 0 | 107 |
| 99 | Killingworth | 6 | 4 | 0 | 87 |
| 100 | Bridgewater | 6 | 4 | 0 | 51 |
| 101 | Westbrook | 8 | 4 | 0 | 50 |
| 102 | Harwinton | 5 | 4 | 0 | 40 |
| 103 | Roxbury | 6 | 4 | 0 | 0 |
| 104 | East Hampton | 3 | 3 | 0 | 540 |
| 105 | East Granby | 4 | 3 | 0 | 360 |
| 106 | New Hartford | 5 | 3 | 0 | 312 |
| 107 | Colchester | 8 | 3 | 0 | 276 |
| 108 | North Branford | 4 | 3 | 0 | 228 |
| 109 | Essex | 5 | 3 | 0 | 208 |
| 110 | Thompson | 5 | 3 | 0 | 205 |
| 111 | Clinton | 5 | 3 | 0 | 110 |
| 112 | Middlefield | 6 | 3 | 0 | 84 |
| 113 | Burlington | 4 | 3 | 0 | 60 |
| 114 | Cornwall | 4 | 3 | 0 | 54 |
| 115 | Barkhamsted | 4 | 3 | 0 | 50 |
| 116 | Voluntown | 4 | 3 | 0 | 42 |
| 117 | Brooklyn | 5 | 3 | 0 | 30 |
| 118 | Andover | 9 | 3 | 0 | 0 |
| 119 | Lisbon | 3 | 2 | 0 | 155 |
| 120 | Morris | 4 | 2 | 0 | 100 |
| 121 | Killingly | 2 | 2 | 0 | 98 |
| 122 | Bolton | 6 | 2 | 0 | 60 |
| 123 | Trumbull | 5 | 2 | 0 | 35 |
| 124 | Granby | 3 | 2 | 0 | 0 |
| 125 | Stafford | 5 | 1 | 0 | 429 |
| 126 | Tolland | 5 | 1 | 0 | 216 |
| 127 | Ashford | 3 | 1 | 0 | 144 |
| 128 | Bloomfield | 4 | 1 | 0 | 104 |
| 129 | Chaplin | 5 | 1 | 0 | 0 |
| 130 | Columbia | 3 | 0 | 0 | 32 |
| 131 | Haddam | 3 | 0 | 0 | 0 |
Recommended Filtration for Connecticut
Based on the most common contaminants found across Connecticut (Nitrate and nitrite, Nitrate, Barium), we recommend a reverse osmosis system or high-quality carbon block filter to remove disinfection byproducts and their precursors.
Echo RO System
Removes up to 99.9% of contaminants. The gold standard for drinking water in Connecticut homes.
View RO SystemsEcho Whole-Home Filter
Protect every tap in your home from chlorine, VOCs, and disinfection byproducts.
View Whole-Home FiltersEcho Hydrogen Water Flask
Once your water is clean, supercharge it with molecular hydrogen for antioxidant and anti-inflammatory benefits.
Shop Hydrogen FlaskFrequently Asked Questions
Is Connecticut tap water safe to drink?
Water quality varies significantly across Connecticut. Of the 131 cities analyzed, the average city has 8.7 contaminants above EWG health guidelines. The best water quality was found in Columbia. We recommend checking your specific city's report for detailed information.
What city has the best water in Connecticut?
Based on our analysis, Columbia has the fewest contaminants above EWG health guidelines in Connecticut, with 0 above guideline levels.
What city has the worst water in Connecticut?
Based on our analysis, Somers has the most contaminants above EWG health guidelines in Connecticut, with 18 above guideline levels.
What's the best water filter for Connecticut residents?
For most Connecticut households, we recommend a reverse osmosis (RO) system for drinking water and a whole-home filter for showers and baths. The specific recommendation depends on your city's contaminant profile — check your city's report for personalized guidance.
National Water Quality Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: March 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
