| AQUA OHIO - ASHTABULA | 32,408 | 24 | Clean |
| ASHTABULA COUNTY WATER SYSTEM | 13,972 | 18 | Clean |
| CONNEAUT | 12,538 | 48 | Clean |
| ANDOVER-CAMPLANDS WATER | 6,009 | 344 | Detected |
| GENEVA CITY PWS | 5,924 | 11 | Clean |
| AQUA OHIO - VILLAGE OF JEFFERSON | 3,226 | 0 | Clean |
| ODNR - PYMATUNING STATE PARK | 2,381 | 91 | — |
| ROAMING SHORES VILLAGE PWS | 1,764 | 47 | — |
| ORWELL VILLAGE PWS | 1,660 | 81 | — |
| ANDOVER VILLAGE PWS | 1,019 | 59 | — |
| ROCK CREEK VILLAGE | 667 | 468 | — |
| BAYSHORE CAMPGROUND PWS | 503 | 35 | — |
| ODOT REST AREA 4-42 PWS | 300 | 6 | — |
| PYMATUNING VALLEY RESORT 3 PWS | 300 | 36 | — |
| WILDWOOD ACRES CAMPGROUND | 244 | 47 | — |
| DOLLAR GENERAL 19942 - WILLIAMSFIELD PWS | 227 | 0 | — |
| DOLLAR GENERAL #23095 - CONNEAUT | 223 | 0 | — |
| DOLLAR GENERAL - 31125 - NEW LYME | 220 | 0 | — |
| DOLLAR GENERAL #30972 - ORWELL | 220 | 0 | — |
| WRIGHT BUILDING | 203 | 68 | — |
| CAMP BEAUMONT, BSA CAMP C PWS | 200 | 36 | — |
| PYMATUNING LAKE DRIVE-IN-THEATER | 200 | 162 | — |
| DOLLAR GENERAL #20931 - PIERPONT, OH | 200 | 5 | — |
| CAMP BEAUMONT, WHISPERING LEAVES PWS | 180 | 23 | — |
| CAMP WHITEWOOD | 180 | 68 | — |
| BUSHNELL STORE PWS | 150 | 6 | — |
| BYLERS COMMUNITY KITCHEN PWS | 128 | 4 | — |
| LOS VENADOS MEXICAN RESTAURANT - ANDOVER | 125 | 49 | — |
| WAGON TRAILS RES - SOUTH WELL | 120 | 71 | — |
| CHERRY VALLEY FURNITURE | 120 | 0 | — |
| HEMLOCK SPRINGS GOLF CLUB | 112 | 6 | — |
| FAMILY DOLLAR - WILLIAMSFIELD | 105 | 0 | — |
| CAMP BEAUMONT, BSA HEALTH CENTER PWS | 100 | 24 | — |
| CAMP KOINONIA - MAIN CAMP PWS | 100 | 55 | — |
| JEFFERSON LANES | 100 | 57 | — |
| JEFFCO LAKES CAMPGROUND | 100 | 102 | — |
| PINE LAKES CAMP - BATH HOUSE PWS | 100 | 8 | — |
| EMERINE ESTATES WINERY PWS | 100 | 0 | — |
| DFC MOBILE HOME PARK | 85 | 633 | — |
| PYMATUNING VALLEY RESORT 1 PWS | 75 | 30 | — |
| PYMATUNING VALLEY RESORT 2 PWS | 75 | 54 | — |
| DORSET CONVENIENCE STORE PWS | 75 | 70 | — |
| HICKORY GROVE GOLF COURSE | 70 | 87 | — |
| HARTSGROVE TAVERN | 60 | 40 | — |
| ROSABELLA WINERY | 60 | 7 | — |
| CAMP BEAUMONT, BSA CAMP A PWS | 50 | 21 | — |
| CAMP BEAUMONT, BSA CUB SCOUT WORLD PWS | 50 | 25 | — |
| CAMP BEAUMONT, BSA CAMP B PWS | 50 | 19 | — |
| PINE LAKES CAMP - PUMP 3 PWS | 50 | 6 | — |
| BLACK ROCK CAMPGROUND-CAMP A | 49 | 44 | — |