| QUINCY WATER DEPT. (MWRA) | 106,000 | 14 | Clean |
| BROOKLINE WATER AND SEWER DIVISION | 63,191 | 16 | Clean |
| WEYMOUTH WATER DEPARTMENT | 57,613 | 50 | Detected |
| RANDOLPH/HOLBROOK JOINT WATER BOARD | 45,767 | 16 | — |
| DEDHAM WESTWOOD WATER DIST. | 41,630 | 11 | Detected |
| BRAINTREE WATER AND SEWER DEPT. | 39,143 | 98 | Detected |
| RANDOLPH WATER DEPARTMENT | 34,362 | 27 | Detected |
| BLUEDROP WATER @ RANDOLPH DPW | 34,362 | 7 | — |
| BLUEDROP WATER @ ST BERNADETTE CHURCH | 34,362 | 0 | — |
| FRANKLIN WATER DEPARTMENT | 33,399 | 44 | Detected |
| NEEDHAM WATER DEPT | 33,130 | 118 | Detected |
| NORWOOD WATER DEPT. (MWRA) | 29,909 | 25 | Clean |
| WELLESLEY WATER DIVISION | 29,550 | 15 | Detected |
| STOUGHTON WATER DEPARTMENT | 29,281 | 45 | Detected |
| MILTON WATER DEPT. (MWRA) | 28,630 | 13 | Clean |
| WALPOLE WATER DEPT | 24,070 | 67 | Detected |
| CANTON WATER DEPT | 22,453 | 38 | Detected |
| FOXBORO WATER DEPARTMENT | 18,639 | 100 | Detected |
| SHARON WATER DEPT | 16,991 | 13 | Detected |
| BELLINGHAM DPW WATER SEWER DIVISION | 16,061 | 78 | Detected |
| MEDWAY WATER DEPARTMENT | 13,115 | 370 | Detected |
| MEDFIELD WATER DEPT. | 12,894 | 135 | Detected |
| WRENTHAM WATER DIVISION | 11,795 | 125 | Detected |
| HOLBROOK PUBLIC WORKS DEPT | 11,405 | 47 | Detected |
| MILLIS WATER DEPT | 9,002 | 98 | Detected |
| PLAINVILLE WATER DEPARTMENT | 8,805 | 62 | Detected |
| NORFOLK WATER DIVISION | 7,602 | 327 | Detected |
| COHASSET WATER DEPT | 7,555 | 64 | Detected |
| TOWN OF AVON | 4,777 | 92 | Detected |
| WELLESLEY COLLEGE | 3,000 | 33 | — |
| HALE EDUCATION, INC. | 3,000 | 5 | — |
| MCI NORFOLK/CEDAR JUNCTION/WALPOLE | 2,200 | 19 | Clean |
| AQUARION WATER COMPANY (DOVER) | 1,922 | 43 | — |
| SOUTHFIELD REDEVELOPEMENT AUTHORITY | 1,800 | 1 | — |
| BLUE HILLS SPRING WATER | 1,500 | 0 | — |
| WRENTHAM DEVELOPMENTAL CENTER | 937 | 22 | — |
| DOVER WATER DEPT | 500 | 86 | — |
| OLD COLONY YMCA STOUGHTON | 475 | 13 | — |
| WENTWORTH HILLS GOLF CLUB | 250 | 9 | — |
| CAMP HAIASTAN | 200 | 35 | — |
| GLEN RIDGE RESIDENTS TRUST | 135 | 28 | — |
| AQUARION WATER CO. (SPRINGDALE FARMS) | 126 | 34 | — |
| POWISSET FARM | 100 | 4 | — |
| MOUNT ST MARYS ABBEY | 60 | 90 | — |
| MEADOWBROOK WATER TRUST | 57 | 26 | — |
| BISHOPS LANDING CONDOMINIUMS | 50 | 25 | — |
| PRECIOUS BEGINNINGS | 44 | 2 | — |
| OLD FARM ROAD WATER TRUST | 40 | 42 | — |
| PRIMO WATER @ WAL MART #2122 | 25 | 2 | — |
| TRI TOWN WATER BOARD | 25 | 2 | — |