| SPRAGUE WATER & SEWER AUTHORITY | BALTIC, CT | 1,058 | 192 | — |
| STRAWBERRY PARK | SALT SPRINGS, CT | 1,047 | 65 | — |
| BROOKFIELD HIGH SCHOOL | BROOKFIELD, CT | 995 | 53 | — |
| AQUARION-RIDGEFIELD KNOLLS | SHELTON, CT | 958 | 228 | — |
| WHISCONIER MIDDLE SCHOOL | BROOKFIELD, CT | 950 | 142 | — |
| ST. BERNARD SCHOOL | UNCASVILLE, CT | 950 | 70 | — |
| AQUARION-NORFOLK | SHELTON, CT | 913 | 19 | — |
| WOODLAKE TAX DISTRICT | WOODBURY, CT | 912 | 63 | — |
| CTWC - AMSTON LAKE DIVISION | CLINTON, CT | 910 | 304 | — |
| FRITO-LAY | DAYVILLE, CT | 903 | 41 | — |
| JOEL BARLOW REGIONAL HIGH SCHOOL | EASTON, CT | 890 | 139 | — |
| NONNEWAUG HIGH SCHOOL | WOODBURY, CT | 887 | 52 | — |
| OAKDALE HEIGHTS ASSOCIATION, INC | GALES FERRY, CT | 876 | 67 | — |
| KENMONT & KENWOOD CAMPS | SOUTH KENT, CT | 825 | 21 | — |
| AQUARION-KENT | SHELTON, CT | 817 | 22 | — |
| SOUTHBURY TRAINING SCHOOL | SOUTHBURY, CT | 816 | 370 | — |
| REDDING ELEMENTARY SCHOOL | EASTON, CT | 811 | 55 | — |
| HADDAM KILLINGWORTH INTER/MIDDLE SCHOOL | KILLINGWORTH, CT | 808 | 308 | — |
| SHARON WATER & SEWER COMMISSION | SHARON, CT | 803 | 309 | — |
| GREENWICH AMERICAN CENTER | GREENWICH, CT | 800 | 288 | Clean |
| HOPEVILLE POND S.P./BEACH-WELL #2 | PORTLAND, CT | 800 | 22 | — |
| HORACE PORTER SCHOOL | COLUMBIA, CT | 797 | 100 | — |
| TALCOTT MOUNTAIN S.P. | PORTLAND, CT | 793 | 22 | — |
| HADDAM MEADOWS S.P. | PORTLAND, CT | 780 | 50 | — |
| SHEPAUG MIDDLE/HIGH SCHOOL | WASHINGTON, CT | 770 | 42 | — |
| BOLTON CENTER SCHOOL (K-8) | BOLTON, CT | 756 | 59 | — |
| HOUSATONIC VALLEY REGIONAL HS | FALLS VILLAGE, CT | 750 | 97 | — |
| CTWC - JENSENS BEECHWOOD SYSTEM | CLINTON, CT | 750 | 447 | — |
| CTWC - UCONN SOUTH EAGLEVILLE DIV. | CLINTON, CT | 750 | 0 | — |
| CLC OWNERS CORPORATION | BROOKFIELD, CT | 736 | 454 | — |
| KENT SCHOOL CORP (VALLEY CAMPUS) | KENT, CT | 722 | 190 | — |
| LAKE GARDA SCHOOL | BURLINGTON, CT | 715 | 27 | — |
| MANSFIELD MIDDLE SCHOOL | MANSFIELD, CT | 715 | 38 | — |
| LAKE WAUBEEKA ASSOCIATION | DANBURY, CT | 712 | 202 | — |
| CTWC - SPICE HILL DIVISION | CLINTON, CT | 712 | 210 | — |
| PENWOOD STATE PARK/MAIN PARK WELL | PORTLAND, CT | 700 | 13 | — |
| CTWC - COVENTRY HILLS DIV | CLINTON, CT | 700 | 27 | Clean |
| MANSFIELD ELEMENTARY SCHOOL | MANSFIELD, CT | 688 | 30 | — |
| INDIAN FIELD COOP CAMPGROUND ASSN., INC. | SALEM, CT | 685 | 223 | — |
| SALEM ELEMENTARY SCHOOL | SALEM, CT | 675 | 93 | — |
| YMCA CAMP INGERSOLL | MIDDLETOWN, CT | 653 | 5 | — |
| SCWA, LEDYARD CENTER DIVISION | GALES FERRY, CT | 652 | 43 | — |
| CTWC - LAKE HAYWARD | CLINTON, CT | 650 | 86 | — |
| HADDAM-KILLINGWORTH HIGH SCHOOL | KILLINGWORTH, CT | 642 | 85 | — |
| ALCOTT SCHOOL | WOLCOTT, CT | 638 | 108 | — |
| WOODSTOCK ELEMENTARY SCHOOL | WOODSTOCK, CT | 636 | 13 | — |
| AQUARION-BALL POND | SHELTON, CT | 629 | 86 | — |
| NATHAN HALE-RAY MIDDLE SCHOOL | MOODUS, CT | 620 | 7 | — |
| LISBON CENTRAL SCHOOL | LISBON, CT | 620 | 41 | — |
| WOODSTOCK ACADEMY SOUTH CAMPUS | WOODSTOCK, CT | 620 | 158 | — |