Water Quality in Connecticut
475 water systems • 114 cities • EPA SDWIS Data
475
Water Systems
28,800
Total Violations
729
Health-Based Violations
2,726,278
Population Served
Overview
Connecticut has 475 active community water systems serving 2,726,278 people. These systems have accumulated 28,800 EPA Safe Drinking Water Act violations on record, of which 729 are health-based violations (meaning a contaminant exceeded safe levels).
Common contaminants found in violations: Stage 2 DBP, Endrin, Disinfection Byproducts, E. coli, TTHM, Total Organic Carbon, Chlorine Dioxide, Fecal Coliform, Gross Alpha, Selenium.
Cities with Most Violations in Connecticut
| # | City | Violations | Health-Based | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | Shelton | 1,690 | 26 | 68 | 698,892 |
| 2 | Danbury | 1,192 | 34 | 13 | 64,443 |
| 3 | East Hartford | 963 | 51 | 11 | 1,313 |
| 4 | Southbury | 830 | 3 | 3 | 928 |
| 5 | Brookfield | 691 | 10 | 5 | 1,343 |
| 6 | New Milford | 633 | 9 | 5 | 1,545 |
| 7 | Old Lyme | 575 | 23 | 5 | 477 |
| 8 | Litchfield | 569 | 1 | 2 | 150 |
| 9 | Niantic | 502 | 4 | 3 | 15,302 |
| 10 | Clinton | 495 | 27 | 63 | 242,947 |
Largest Cities in Connecticut
| # | City | Population | Violations | Water Systems |
|---|---|---|---|---|
| 1 | Shelton | 698,892 | 1,690 | 68 |
| 2 | New Haven | 418,900 | 58 | 1 |
| 3 | Hartford | 390,887 | 4 | 1 |
| 4 | Clinton | 242,947 | 495 | 63 |
| 5 | Waterbury | 107,761 | 96 | 2 |
| 6 | New Britain | 73,534 | 18 | 1 |
| 7 | Danbury | 64,443 | 1,192 | 13 |
| 8 | Meriden | 58,441 | 18 | 1 |
| 9 | Bristol | 52,144 | 35 | 2 |
| 10 | Manchester | 51,282 | 88 | 2 |
All Cities in Connecticut
| City | Population | Violations | Health Violations | Contaminants |
|---|---|---|---|---|
| Shelton | 698,892 | 1,690 | 26 | Bromate, Disinfection Byproducts, E. coli +2 more |
| New Haven | 418,900 | 58 | 0 | |
| Hartford | 390,887 | 4 | 0 | |
| Clinton | 242,947 | 495 | 27 | Chlorine Dioxide, Disinfection Byproducts, E. coli +3 more |
| Waterbury | 107,761 | 96 | 6 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| New Britain | 73,534 | 18 | 0 | |
| Danbury | 64,443 | 1,192 | 34 | Disinfection Byproducts, E. coli, Gross Alpha +2 more |
| Meriden | 58,441 | 18 | 4 | Chlorine Dioxide, Disinfection Byproducts, Total Haloacetic Acids (HAA5) |
| Bristol | 52,144 | 35 | 0 | |
| Manchester | 51,282 | 88 | 0 | |
| Waterford | 44,198 | 43 | 0 | |
| Middletown | 43,977 | 112 | 1 | Stage 2 DBP |
| Southington | 43,069 | 356 | 0 | |
| Wilton | 42,060 | 27 | 3 | Contaminant 2920 |
| Norwalk | 40,356 | 8 | 1 | Chlorine Dioxide |
| Wallingford | 37,351 | 309 | 3 | Chlorine Dioxide, Stage 2 DBP |
| Norwich | 36,497 | 90 | 27 | Chlorine Dioxide, Disinfection Byproducts, E. coli +3 more |
| Groton | 32,600 | 37 | 0 | |
| Storrs | 27,975 | 248 | 7 | Disinfection Byproducts, E. coli, Gross Alpha +1 more |
| Enfield | 26,458 | 188 | 4 | Fecal Coliform, Stage 2 DBP, Total Haloacetic Acids (HAA5) |
| Mansfield Center | 21,214 | 5 | 0 | |
| Niantic | 15,302 | 502 | 4 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| Cromwell | 14,316 | 55 | 0 | |
| Gales Ferry | 12,762 | 110 | 9 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| Bethel | 10,950 | 231 | 6 | E. coli, TTHM |
| Oakville | 10,572 | 40 | 0 | |
| Berlin | 8,003 | 402 | 1 | Stage 2 DBP |
| Winsted | 7,784 | 44 | 1 | Fecal Coliform |
| Putnam | 7,681 | 245 | 8 | Gross Alpha, Stage 2 DBP |
| Kensington | 7,553 | 26 | 0 | |
| Watertown | 7,096 | 438 | 2 | Stage 2 DBP |
| Ledyard | 5,663 | 16 | 5 | TTHM |
| Portland | 5,106 | 56 | 2 | Fecal Coliform, Stage 2 DBP |
| Colchester | 4,244 | 60 | 3 | E. coli, Stage 2 DBP |
| Newtown | 3,114 | 88 | 3 | Disinfection Byproducts, Stage 2 DBP |
| Wolcott | 2,550 | 25 | 0 | |
| Wethersfield | 2,385 | 22 | 1 | Barium |
| Granby | 2,151 | 20 | 0 | |
| Tolland | 2,130 | 325 | 27 | Chlorine Dioxide, Disinfection Byproducts, E. coli +3 more |
| Durham | 2,111 | 259 | 7 | Chlorine Dioxide, Disinfection Byproducts, E. coli +1 more |
| Uncasville | 1,958 | 308 | 11 | Disinfection Byproducts, E. coli, Stage 2 DBP +1 more |
| Noank | 1,947 | 22 | 0 | |
| East Hampton | 1,571 | 435 | 5 | Chlorine Dioxide, Disinfection Byproducts, Stage 2 DBP |
| New Milford | 1,545 | 633 | 9 | E. coli, Gross Alpha, Stage 2 DBP |
| Tariffville | 1,477 | 36 | 2 | E. coli |
| Brookfield | 1,343 | 691 | 10 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| East Hartford | 1,313 | 963 | 51 | Barium, Disinfection Byproducts, E. coli +2 more |
| Willington | 1,158 | 53 | 3 | Stage 2 DBP |
| Kent | 1,104 | 74 | 1 | Disinfection Byproducts |
| Baltic | 1,058 | 10 | 0 | |
| Woodbury | 1,020 | 151 | 0 | |
| Vernon | 964 | 61 | 4 | Chlorine Dioxide, Stage 2 DBP |
| Southbury | 928 | 830 | 3 | Chlorine Dioxide, E. coli, Stage 2 DBP |
| Sharon | 919 | 232 | 2 | Fecal Coliform, Stage 2 DBP |
| Woodstock | 900 | 97 | 7 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| New Fairfield | 880 | 380 | 8 | E. coli, Stage 2 DBP |
| Pomfret | 700 | 34 | 2 | Stage 2 DBP |
| Washington | 698 | 234 | 0 | |
| Plainville | 603 | 17 | 0 | |
| Stamford | 592 | 239 | 11 | Chlorine Dioxide, Disinfection Byproducts, E. coli +1 more |
| Branford | 591 | 190 | 0 | |
| Greenwich | 567 | 53 | 1 | Disinfection Byproducts |
| Mashantucket | 550 | 11 | 1 | E. coli |
| Mystic | 532 | 123 | 3 | Disinfection Byproducts, Stage 2 DBP |
| Salisbury | 520 | 8 | 0 | |
| Thompson | 497 | 363 | 22 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| Old Lyme | 477 | 575 | 23 | Chlorine Dioxide, Disinfection Byproducts, E. coli +2 more |
| Goshen | 462 | 53 | 2 | E. coli |
| Windham | 447 | 13 | 1 | E. coli |
| Stafford | 429 | 7 | 0 | |
| Montvale | 397 | 192 | 6 | Chlorine Dioxide, Disinfection Byproducts, Stage 2 DBP |
| Monsey | 381 | 296 | 15 | Chlorine Dioxide, Disinfection Byproducts, E. coli +1 more |
| East Granby | 360 | 14 | 1 | Stage 2 DBP |
| Canterbury | 337 | 57 | 12 | Disinfection Byproducts, E. coli |
| Oakdale | 335 | 73 | 6 | Disinfection Byproducts, Endrin, Stage 2 DBP |
| Simsbury | 325 | 217 | 1 | Stage 2 DBP |
| New York | 316 | 61 | 2 | Stage 2 DBP |
| Oneco | 308 | 4 | 0 | |
| Bolton | 301 | 98 | 13 | E. coli, Stage 2 DBP |
| Seymour | 288 | 20 | 6 | Copper, Disinfection Byproducts |
| Bloomfield | 282 | 156 | 19 | Chlorine Dioxide, Disinfection Byproducts, E. coli +1 more |
| Weatogue | 270 | 4 | 0 | |
| Farmington Hills | 258 | 19 | 0 | |
| Marlborough | 251 | 46 | 1 | Stage 2 DBP |
| Stafford Springs | 250 | 37 | 1 | Stage 2 DBP |
| Middlefield | 241 | 200 | 2 | E. coli, Stage 2 DBP |
| Naugatuck | 240 | 114 | 0 | |
| Avon | 238 | 6 | 1 | Stage 2 DBP |
| South Kent | 228 | 25 | 1 | Stage 2 DBP |
| New Preston | 223 | 12 | 1 | Stage 2 DBP |
| Ashford | 220 | 147 | 6 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| Okemos | 218 | 59 | 1 | Disinfection Byproducts |
| Las Vegas | 215 | 26 | 1 | E. coli |
| South Windsor | 208 | 30 | 1 | Stage 2 DBP |
| Essex | 208 | 2 | 0 | |
| Quinebaug | 205 | 34 | 6 | Barium, Stage 2 DBP |
| Glastonbury | 204 | 32 | 3 | E. coli, Stage 2 DBP |
| Quaker Hill | 180 | 13 | 2 | Disinfection Byproducts |
| Lebanon | 172 | 114 | 1 | Stage 2 DBP |
| Broad Brook | 171 | 46 | 5 | Stage 2 DBP, Total Organic Carbon |
| Dayville | 169 | 56 | 10 | Disinfection Byproducts, E. coli, Stage 2 DBP |
| Coventry | 160 | 43 | 0 | |
| Sandy Hook | 158 | 194 | 3 | Chlorine Dioxide, Total Organic Carbon |
| Litchfield | 150 | 569 | 1 | Disinfection Byproducts |
| Willimantic | 148 | 62 | 1 | Stage 2 DBP |
| Bethlehem | 140 | 18 | 3 | Total Organic Carbon |
| Bantam | 136 | 73 | 0 | |
| Cobalt | 130 | 56 | 1 | Stage 2 DBP |
| East Haddam | 121 | 99 | 2 | E. coli, Stage 2 DBP |
| Moodus | 120 | 17 | 4 | Disinfection Byproducts, E. coli |
| Washington Depot | 120 | 24 | 0 | |
| Burlington | 111 | 66 | 1 | Disinfection Byproducts |
| Prospect | 102 | 10 | 1 | Stage 2 DBP |
| Weston | 100 | 39 | 2 | Disinfection Byproducts |
Data Sources
Drinking water data from the EPA Safe Drinking Water Information System (SDWIS). Only active community water systems (CWS) serving 100+ people are included.