| LYNN WATER AND SEWER COMM | 101,253 | 39 | Detected |
| SALEM AND BEVERLY WATER SUPPLY BOARD | 90,330 | 19 | — |
| LAWRENCE WATER WORKS | 88,877 | 296 | Detected |
| HAVERHILL WATER DEPT | 63,235 | 80 | Clean |
| PEABODY WATER DEPT. | 54,481 | 180 | Detected |
| METHUEN WATER DEPT | 53,059 | 51 | Detected |
| BEVERLY WATER DEPT | 47,461 | 9 | Detected |
| SALEM WATER DEPARTMENT | 44,480 | 7 | Detected |
| GLOUCESTER PUBLIC UTILITY DIVISION | 37,440 | 171 | Clean |
| ANDOVER WATER DEPT | 36,569 | 7 | Detected |
| NORTH ANDOVER WATER DEPT | 30,915 | 56 | Clean |
| DANVERS WATER DEPT. | 28,087 | 56 | Detected |
| SAUGUS WATER DEPT. (MWRA) | 27,082 | 26 | Clean |
| MARBLEHEAD WATER DEPT. (MWRA) | 20,441 | 13 | Clean |
| NEWBURYPORT WATER DEPARTMENT | 20,335 | 74 | Detected |
| SALISBURY WATER DIVISION | 20,000 | 47 | Detected |
| AMESBURY DPW WATER DIV. | 17,366 | 38 | Clean |
| SWAMPSCOTT WATER DEPT. (MWRA) | 15,175 | 28 | Clean |
| IPSWICH DPU WATER DEPT | 13,090 | 75 | Detected |
| ROCKPORT WATER DEPT | 10,000 | 27 | Clean |
| GEORGETOWN WATER DEPARTMENT | 8,766 | 100 | Clean |
| LYNNFIELD CENTER WATER DISTRICT | 8,569 | 154 | Detected |
| HAMILTON WATER DEPT | 7,377 | 84 | Detected |
| MIDDLETON WATER DEPT. | 7,255 | 18 | Detected |
| MERRIMAC WATER DEPARTMENT | 7,193 | 276 | Detected |
| GROVELAND WATER DEPARTMENT | 6,743 | 46 | Detected |
| ROWLEY WATER DEPARTMENT | 6,283 | 112 | Detected |
| TOPSFIELD WATER DEPARTMENT | 5,435 | 72 | Detected |
| MANCHESTER BY THE SEA DPW | 5,170 | 94 | Detected |
| LYNNFIELD WATER DIST. (MWRA) | 4,820 | 14 | Clean |
| WENHAM WATER DEPT. | 3,942 | 23 | Detected |
| ESSEX WATER DEPT. | 3,675 | 43 | — |
| NAHANT WATER DEPT. (MWRA) | 3,334 | 29 | Clean |
| WEST NEWBURY WATER DEPARTMENT | 3,080 | 11 | Detected |
| BYFIELD WATER DISTRICT | 2,228 | 35 | — |
| PEQUOT HIGHLANDS | 900 | 0 | — |
| ROCKY MOUNTAIN SPRING WATER VENDING | 500 | 0 | — |
| SPOFFORD POND SCHOOL | 486 | 67 | — |
| HARRY LEE COLE SCHOOL | 439 | 91 | — |
| SAGAMORE SPRING GOLF CLUB, INC. | 250 | 2 | — |
| THE WATER STORE OF SAUGUS (VND) | 250 | 5 | — |
| BOXFORD COMMUNITY STORE INC | 200 | 10 | — |
| IPSWICH RIVER WILDLIFE REFUGE | 180 | 0 | — |
| THE VILLAGE STORE BLDG. | 150 | 54 | — |
| ANDREWS FARM WATER CO.,INC. | 150 | 163 | — |
| ESSEX MEETING AND RETREAT CENTER, LLC | 150 | 8 | — |
| FOUR MILE VILLAGE | 133 | 133 | — |
| FAR CORNER FARM GOLF COURSE INC. | 120 | 7 | — |
| BOXFORD MEETING PLACE | 120 | 8 | — |
| INGALDSBY BAKERY AND FARM STAND | 100 | 8 | — |