| SAN GABRIEL VALLEY WC - FONTANA | 237,700 | 3 | Clean |
| SAN BERNARDINO CITY | 214,665 | 2 | Detected |
| CUCAMONGA VALLEY WATER DISTRICT | 211,069 | 5 | Clean |
| ONTARIO MUNICIPAL UTILITIES COMPANY | 185,010 | 9 | Detected |
| VICTORVILLE WATER DISTRICT | 135,983 | 13 | Detected |
| SAN BERNARDINO VALLEY WD | 109,608 | 2 | — |
| EAST VALLEY WATER DISTRICT | 108,629 | 13 | Detected |
| WEST VALLEY WATER DISTRICT | 104,498 | 19 | Clean |
| HESPERIA WD | 100,744 | 7 | Detected |
| CHINO, CITY OF | 86,435 | 44 | Clean |
| BIG BEAR ADMINISTRATION | 81,075 | 12 | — |
| UPLAND, CITY OF | 78,376 | 10 | Detected |
| REDLANDS CITY MUD-WATER DIV | 78,025 | 11 | Detected |
| CHINO HILLS, CITY OF | 76,414 | 43 | Clean |
| SNOW SUMMIT | 75,500 | 45 | — |
| LIBERTY UTILITIES (AV RANCHOS) CORP. | 64,469 | 2 | Detected |
| PARK MOABI | 64,267 | 2 | — |
| MONTE VISTA WD | 56,017 | 27 | Detected |
| RIALTO, CITY OF | 54,453 | 6 | Detected |
| YUCAIPA VALLEY WATER DISTRICT | 52,010 | 19 | Detected |
| COLTON, CITY OF | 46,525 | 3 | Detected |
| ADELANTO, CITY OF | 39,930 | 40 | Detected |
| GOLDEN STATE WATER CO - BARSTOW | 32,547 | 2 | Detected |
| HI DESERT WD | 26,411 | 17 | Detected |
| BIG BEAR LAKE DWP - BIG BEAR SYSTEM | 26,132 | 3 | Detected |
| LOMA LINDA, CITY OF | 25,129 | 9 | Clean |
| CALICO GHOST TOWN | 24,623 | 131 | — |
| PHELAN PINON HILLS CSD | 24,285 | 3 | Clean |
| RIVERSIDE HIGHLAND WATER COMPANY | 20,188 | 6 | Detected |
| TWENTYNINE PALMS WATER DISTRICT | 18,795 | 254 | Detected |
| US ARMY FORT IRWIN | 15,701 | 146 | Detected |
| LOMA LINDA UNIVERSITY | 15,368 | 5 | Detected |
| USMC - 29 PALMS | 15,248 | 11 | Clean |
| THOUSAND PINES CHRISTIAN | 15,034 | 5 | — |
| SBDNO COUNTY SERVICE AREA 64 | 14,911 | 7 | Clean |
| HANNA FLATS CAMPGROUND | 14,380 | 0 | — |
| MUSCOY MWC NO. 1 | 13,000 | 45 | Clean |
| SBDNO COUNTY SERVICE AREA 70J | 12,843 | 5 | Clean |
| BIG BEAR CITY CSD | 12,738 | 1 | Detected |
| CRESTLINE VILLAGE CWD - DIVISION 10 | 11,650 | 10 | Detected |
| CALIFORNIA INSTITUTION FOR MEN | 10,667 | 35 | Clean |
| GREEN VALLEY CAMPGROUND | 9,939 | 0 | — |
| NEEDLES, CITY OF | 8,766 | 17 | Detected |
| WESTERN HEIGHTS WATER COMPANY | 7,705 | 6 | Clean |
| LAKE ARROWHEAD CSD | 7,038 | 0 | Detected |
| ARROWHEAD REGIONAL MEDICAL CENTER | 7,000 | 4 | — |
| JOSHUA BASIN WATER DISTRICT | 6,640 | 9 | Detected |
| YMCA CAMP WHITTLE | 6,466 | 15 | — |
| HELENDALE COMMUNITY SERVICE DISTRICT | 6,347 | 51 | Detected |
| GOLDEN STATE WATER CO - APPLE VLY SOUTH | 6,208 | 1 | Detected |