| REHOBOTH PUMP DISTRICT (TUI) | 81,417 | 9 | Detected |
| BETHANY BAY PUMP DISTRICT | 51,000 | 11 | Detected |
| DEWEY BEACH WATER DEPARTMENT | 31,000 | 4 | Detected |
| REHOBOTH BEACH WATER DEPARTMENT | 25,000 | 0 | Detected |
| ARTESIAN SOUTHERN SUSSEX REGIONAL | 18,015 | 11 | Detected |
| SUSSEX SHORES WATER COMPANY | 12,450 | 9 | Clean |
| BETHANY BEACH WATER DEPARTMENT | 12,000 | 21 | Clean |
| LONG NECK WATER COMPANY | 11,000 | 20 | Clean |
| LEWES BOARD OF PUBLIC WORKS | 9,627 | 11 | Detected |
| MILLSBORO WATER DEPARTMENT | 8,568 | 25 | Clean |
| BAYSIDE PUMP DISTRICT (TUI) | 8,400 | 4 | Detected |
| GEORGETOWN WATER DEPARTMENT | 7,259 | 2 | Detected |
| SEAFORD WATER DEPARTMENT | 6,699 | 23 | Detected |
| BRIDGEVILLE WATER DEPARTMENT | 6,000 | 11 | Detected |
| ARTESIAN NORTHERN SUSSEX REGIONAL | 5,511 | 2 | Detected |
| LAUREL WATER DEPARTMENT | 3,984 | 14 | Clean |
| SELBYVILLE WATER DEPARTMENT | 3,502 | 26 | — |
| MILTON WATER DEPARTMENT | 3,200 | 20 | — |
| BROADKILN BEACH WATER COMPANY (TUI) | 3,171 | 28 | — |
| STOCKLEY REGIONAL | 2,761 | 0 | — |
| DELMAR UTILITY COMM (TN OF DELMAR) | 2,027 | 11 | Clean |
| SUSSEX TECHNICAL SCHOOL DISTRICT | 1,800 | 12 | — |
| SWANN KEYS | 1,764 | 3 | Clean |
| GULLS WAY CAMPGROUND | 1,617 | 26 | — |
| REHOBOTH BAY COMMUNITY | 1,575 | 28 | — |
| BRIDGEVILLE PUMP DISTRICT | 1,542 | 5 | — |
| ALLEN HARIM FOODS INC | 1,500 | 10 | — |
| PERDUE FOODS LLC | 1,500 | 0 | — |
| TRAP POND STATE PARK SYSTEM 2-NATURE CTR | 1,500 | 0 | — |
| MALLARD LAKES | 1,500 | 0 | — |
| ANGOLA BEACH ESTATES | 1,400 | 20 | — |
| HOLLY LAKE CAMPSITES SYSTEM 2 | 1,375 | 9 | — |
| BLADES, TOWN OF | 1,200 | 24 | — |
| MOUNTAIRE-MILLSBORO | 1,200 | 93 | — |
| TRAP POND STATE PARK SYSTEM 3 - CAMPING | 1,000 | 4 | — |
| GREENWOOD WATER DEPARTMENT | 973 | 44 | — |
| DAGSBORO WATER DEPT | 934 | 12 | — |
| LAUREL VILLAGE MHC | 918 | 21 | — |
| DE-LUX DAIRY MARKET - SEAFORD | 916 | 30 | — |
| BAYWOOD GREENS | 909 | 0 | — |
| TUCKAHOE ACRES SYSTEM #2 | 900 | 12 | — |
| HOLLY LAKE CAMPSITES SYSTEM 3 | 900 | 9 | — |
| SLAUGHTER BEACH PWS | 846 | 4 | — |
| TREASURE BEACH CAMPGROUND SYSTEM 1 | 786 | 0 | — |
| EVELYN MORRIS ELEMENTARY SCHOOL | 780 | 0 | — |
| TREASURE BEACH CAMPGROUND SYSTEM 2 | 771 | 0 | — |
| CLEARBROOKE ESTATES PUMP DISTRICT | 768 | 1 | — |
| TUCKAHOE ACRES SYSTEM #1 | 750 | 43 | — |
| STOCKLEY CENTER | 749 | 18 | — |
| TREASURE BEACH CAMPGROUND SYSTEM 4 | 699 | 5 | — |