| UNIVERSITY OF CONNECTICUT - MAIN CAMPUS | 27,199 | 66 | Detected |
| CTWC - HEBRON CENTER DIVISION | 1,927 | 2 | — |
| COVENTRY HIGH & NATHAN HALE SCHOOLS | 1,252 | 18 | — |
| TOLLAND WATER DEPARTMENT | 1,251 | 19 | — |
| CTWC - AMSTON LAKE DIVISION | 910 | 304 | — |
| HORACE PORTER SCHOOL | 797 | 100 | — |
| BOLTON CENTER SCHOOL (K-8) | 756 | 59 | — |
| CTWC - UCONN SOUTH EAGLEVILLE DIV. | 750 | 0 | — |
| MANSFIELD MIDDLE SCHOOL | 715 | 38 | — |
| CTWC - COVENTRY HILLS DIV | 700 | 27 | Clean |
| MANSFIELD ELEMENTARY SCHOOL | 688 | 30 | — |
| GEORGE HERSEY ROBERTSON SCHOOL | 573 | 9 | — |
| COVENTRY GRAMMAR SCHOOL | 558 | 100 | — |
| CTWC - SOUTH COVENTRY SYSTEM | 501 | 232 | — |
| WOODHAVEN APARTMENTS | 489 | 78 | — |
| CTWC - NORTHERN REGION-LAKEVIEW TERRACE | 472 | 12 | — |
| HEBRON ELEMENTARY SCHOOL | 450 | 21 | — |
| VERNON VILLAGE INC. | 430 | 31 | — |
| STAFFORD HOLLOW WATER ASSOCIATION | 429 | 43 | — |
| GILEAD HILL SCHOOL | 391 | 9 | — |
| ANDOVER ELEMENTARY SCHOOL | 381 | 71 | — |
| HAZARDVILLE - RYE HILL SYSTEM | 352 | 4 | — |
| WILLINGTON SENIOR CENTER & HOUSING | 327 | 9 | — |
| KNOLLWOOD APARTMENTS | 312 | 108 | — |
| CTWC - GENERAL WATER DIVISION | 306 | 22 | — |
| BOLTON HIGH SCHOOL | 304 | 81 | — |
| JUSTICE EDUCATION CENTER CAMP INSPIRE | 300 | 69 | — |
| WALDEN APARTMENTS | 276 | 167 | — |
| CRYSTAL LAKE SCHOOL | 275 | 60 | — |
| CTWC - NORTHERN REGION-LAKEWOOD | 256 | 143 | — |
| JOHNSON MEMORIAL HOSPITAL, INC | 250 | 172 | — |
| CTWC - UCONN HUNTING LODGE DIV. | 234 | 0 | — |
| CTWC - PILGRIM HILLS DIVISION | 229 | 23 | — |
| CTWC - LONDON PARK DIVISION | 221 | 29 | — |
| MANSFIELD LIBRARY BUCHANAN CENTER | 217 | 6 | — |
| WOODLAND SUMMIT COMMUNITY WATER ASSN | 216 | 58 | — |
| IVY WOODS | 207 | 151 | — |
| TOLLAND WATER DEPT - TORRY ROAD | 204 | 16 | — |
| 1657 BOSTON TURNPIKE - COVENTRY | 203 | 81 | — |
| FED EX GROUND | 200 | 111 | — |
| CARRIAGE HOUSE APARTMENTS | 196 | 97 | — |
| CORNERSTONE OF COLUMBIA | 193 | 0 | — |
| CTWC - NORTHERN REG-LLYNWOOD SYSTEM | 192 | 148 | — |
| WHITE OAK CONDOMINIUMS | 192 | 51 | — |
| RENWOOD APARTMENTS | 190 | 144 | — |
| DISCOVERY ZONE LEARNING CNTR COLUMBIA | 189 | 29 | — |
| CTWC - RIVERSEDGE DIVISION | 179 | 25 | — |
| ORCHARD ACRES ASSOCIATION | 176 | 61 | — |
| BAXTER FARMS COMMUNITY WATER ASSOC | 175 | 31 | — |
| CTWC - CRYSTAL SPRINGS DIV. | 169 | 9 | — |