| 1 | Sensenig & Weaver Well Drilling Inc. | 836 | 3,360 | 18,480 |
| 2 | Thomas Keyes, Inc. | 595 | 3,745 | 5,253 |
| 3 | Myers Brothers Drilling Contr.,Inc. | 423 | 1,986 | 33,477 |
| 4 | Ameridrill, Inc. | 391 | 634 | 5,442 |
| 5 | C S Garber & Sons Inc. | 347 | 2,678 | 18,484 |
| 6 | Odyssey Environmental Services, Inc. | 328 | 397 | 7,584 |
| 7 | Eichelbergers Inc. | 307 | 1,138 | 37,074 |
| 8 | Edward Powell Pump & Well Drilling Inc. | 300 | 2,227 | 4,204 |
| 9 | Petersheim Brothers H20,LLC | 241 | 2,696 | 8,096 |
| 10 | Allied Well Drilling | 230 | 429 | 2,213 |
| 11 | K.l. Madron Well Drilling, LLC | 220 | 4,179 | 5,980 |
| 12 | Brown Bros Drilling & Service | 217 | 1,583 | 5,569 |
| 13 | East Coast Drilling, Inc. | 108 | 109 | 1,106 |
| 14 | Mills Well Drilling, LLC | 64 | 891 | 1,003 |
| 15 | Environmental Probing Investigations Inc. | 61 | 77 | 1,212 |
| 16 | Parratt-Wolff Inc. | 46 | 73 | 3,500 |
| 17 | Talon Drilling Company | 44 | 241 | 1,966 |
| 18 | Summit Drilling LLC | 42 | 46 | 1,492 |
| 19 | Powell Drilling And Services | 40 | 188 | 337 |
| 20 | Accell Inc. | 17 | 17 | 116 |
| 21 | Marti Cascade | 16 | 25 | 342 |
| 22 | Mayer's Well Drilling | 12 | 86 | 2,948 |
| 23 | Advanced Drilling Inc. | 7 | 27 | 248 |
| 24 | Active Environmental Technologies, Inc. | 6 | 6 | 206 |
| 25 | Chris Cook - C W Cook, Inc. | 5 | 12 | 274 |
| 26 | Tristate Env. Mgmt. Svcs. Inc. | 5 | 9 | 199 |
| 27 | Logan Bollinger | 3 | 32 | 795 |
| 28 | Michael Barlow Well Drilling Service | 3 | 7 | 81 |
| 29 | Hawk Drilling | 3 | 3 | 480 |
| 30 | Miller Pump Service Inc. | 2 | 212 | 2,893 |
| 31 | Morrison Excavating Morrison Excavating Inc. | 2 | 6 | 1,160 |
| 32 | G S Fleese Drillin | 2 | 3 | 248 |
| 33 | Mountain Research LLC | 2 | 2 | 1,243 |
| 34 | George Leib Well Drilling Inc. | 2 | 2 | 908 |
| 35 | Awt Environmental Services Inc. | 1 | 1 | 111 |
| 36 | B. L. Myers Bros OF MD,LLC | — | 5,115 | 12,524 |
| 37 | George R. Brookover Well Drlg | — | 1,574 | 1,754 |
| 38 | B L Myers Bros Inc. | — | 1,125 | 1,232 |
| 39 | Calvin E.powell-Powell Drilling & Srvc | — | 997 | 1,322 |
| 40 | R Walter Slauch & Sons | — | 777 | 827 |
| 41 | Robert E Mattson | — | 396 | 448 |
| 42 | Leroy Myers | — | 311 | 319 |
| 43 | Walton Corporation | — | 295 | 335 |
| 44 | Michael Kuszyk | — | 246 | 652 |
| 45 | Arthur Astle Well Drilling | — | 240 | 454 |
| 46 | J E Brewer | — | 215 | 244 |
| 47 | Douglas K Reigner | — | 127 | 396 |
| 48 | Bonnie J Myers | — | 125 | 134 |
| 49 | Alfred G Gurley | — | 112 | 115 |
| 50 | Roger Leeds Well Drilling | — | 103 | 298 |
| 51 | Todd Mayer's Well Drilling | — | 100 | 5,307 |
| 52 | J Normal Connell | — | 96 | 101 |
| 53 | Charles Lauman And Son Inc. | — | 89 | 338 |
| 54 | Kohl Bros., Inc. | — | 88 | 2,398 |
| 55 | Lloyd R Gurley | — | 82 | 85 |
| 56 | Aquapur Inc. | — | 61 | 61 |
| 57 | Gurvis Gurvis Jones Well Drilling, Inc. | — | 37 | 93 |
| 58 | Water Well Drillers Licensing--Topo Geo | — | 30 | 732 |
| 59 | Hope Womble | — | 28 | 29 |
| 60 | Jackson Geothermal Hvac & Drilling LLC | — | 27 | 34 |
| 61 | Vonley Ray | — | 24 | 28 |
| 62 | Leonard R Mayberry | — | 23 | 25 |
| 63 | R And R Garber Inc. | — | 20 | 732 |
| 64 | Sjb Services, Inc. | — | 20 | 44 |
| 65 | Lininger Drilling & Pumps | — | 19 | 773 |
| 66 | Handex Consulting & Remediation, LLC | — | 19 | 575 |
| 67 | William W. Reichart, Inc. | — | 17 | 3,242 |
| 68 | Alexander Macphee--Cvm Industries | — | 14 | 495 |
| 69 | Artesian Well Drlg Co. | — | 12 | 144 |
| 70 | Raab Well Drilling, Inc. | — | 11 | 2,909 |
| 71 | A C Reider Inc. | — | 11 | 2,336 |
| 72 | Green Mountain Construction & Equip Corp | — | 11 | 26 |
| 73 | Kerr Bros | — | 10 | 121 |
| 74 | Enviroprobe Service, Inc. | — | 9 | 183 |
| 75 | Bucks County Well Drilling, Inc. | — | 9 | 3,006 |
| 76 | Lutz Environmental Co., Inc. | — | 9 | 431 |
| 77 | Ridpath And Potter Company | — | 9 | 249 |
| 78 | Tabasco Drilling Corporation | — | 8 | 139 |
| 79 | Plainfield Well Drilling Co. | — | 8 | 79 |
| 80 | Marcor Environmental Service Inc. | — | 7 | 67 |
| 81 | W F Kerr | — | 7 | 46 |
| 82 | AC Schultes Inc. | — | 6 | 115 |
| 83 | M & R Soil Investigations Inc. | — | 6 | 74 |
| 84 | Thomas B Harper | — | 4 | 209 |
| 85 | Debco Drilling Company | — | 4 | 154 |
| 86 | Philadelphia Drilling Co. | — | 4 | 42 |
| 87 | Jones Drilling And Pump Co. | — | 4 | 29 |
| 88 | Duane Moyer Well Drilling | — | 3 | 11,486 |
| 89 | Kocher's Water Pumps & Tanks Inc. | — | 3 | 2,402 |
| 90 | Root Contracting LLC | — | 3 | 134 |
| 91 | Harrisburg's Kohl Bros Inc. | — | 3 | 2,819 |
| 92 | Allen H Dorn | — | 3 | 1,787 |
| 93 | Snyder Well Drilling Inc. | — | 3 | 1,464 |
| 94 | R R Hornberger | — | 3 | 508 |
| 95 | Lester W Kocher | — | 3 | 278 |
| 96 | James Bucci | — | 3 | 81 |
| 97 | Evans Well Drilling | — | 2 | 215 |
| 98 | Phares Fry Well Drilling | — | 2 | 3,694 |
| 99 | Greening Drilling Company | — | 2 | 753 |
| 100 | H K Honberger & Son | — | 2 | 414 |
| 101 | IT Environmental Inc. | — | 2 | 131 |
| 102 | C & I Enterprises | — | 2 | 105 |
| 103 | Henry's Well Drilling | — | 2 | 95 |
| 104 | Floyd R Sensenig | — | 2 | 78 |
| 105 | Quinn & Herron | — | 2 | 36 |
| 106 | Miller Bros W W Drlg | — | 2 | 26 |
| 107 | Sprague & Henwood Inc. | — | 2 | 25 |
| 108 | Duane Cizek | — | 1 | 1,894 |
| 109 | Coudersport Well Drilling Inc. | — | 1 | 1,813 |
| 110 | T W Cummings Well Drilling | — | 1 | 1,712 |
| 111 | Robert D Grant | — | 1 | 1,090 |
| 112 | Jim Hubler Well Drilling | — | 1 | 973 |
| 113 | Fisher's Well Drilling | — | 1 | 551 |
| 114 | Anderson Well Drilling & Pump Sales | — | 1 | 486 |
| 115 | Clair A Spahn | — | 1 | 384 |
| 116 | Mckay & Gould Drilling, Inc. | — | 1 | 362 |
| 117 | Christopher Kasa / Casey-Kassa Drilling Co. | — | 1 | 350 |
| 118 | Arthur Reinheimer Layne Christensen Company | — | 1 | 225 |
| 119 | William R Parks JR | — | 1 | 213 |
| 120 | Ferguson Brothers | — | 1 | 151 |
| 121 | David Lyman/Samuel Stothoff Co., Inc. | — | 1 | 149 |
| 122 | Charles W Shoff | — | 1 | 129 |
| 123 | Glenn E Houp | — | 1 | 108 |
| 124 | R J Nock & Son | — | 1 | 91 |
| 125 | Gilford Drilling | — | 1 | 86 |
| 126 | William Stothoff Co. Inc. | — | 1 | 70 |
| 127 | Rulon And Cook Inc. | — | 1 | 68 |
| 128 | John Michell | — | 1 | 66 |
| 129 | Cook Environmental Services Corporation | — | 1 | 59 |
| 130 | Environmental Management Associates | — | 1 | 53 |
| 131 | William H Lamberson | — | 1 | 47 |
| 132 | Layne Christensen Company | — | 1 | 44 |
| 133 | Nathan L Walters | — | 1 | 31 |
| 134 | Frank L Hisey | — | 1 | 26 |
| 135 | Nfe Inc. | — | 1 | 26 |
| 136 | Jesse M Knapenberger | — | 1 | 25 |