| 1 | Eichelbergers Inc. | 1,502 | 7,224 | 37,074 |
| 2 | Myers Brothers Drilling Contr.,Inc. | 453 | 1,617 | 33,477 |
| 3 | Odyssey Environmental Services, Inc. | 368 | 507 | 7,584 |
| 4 | Sensenig & Weaver Well Drilling Inc. | 228 | 504 | 18,480 |
| 5 | William W. Reichart, Inc. | 134 | 2,046 | 3,242 |
| 6 | Negley's Well Drilling, LLC | 111 | 156 | 9,098 |
| 7 | Alexander's | 106 | 301 | 3,447 |
| 8 | Ameridrill, Inc. | 58 | 230 | 5,442 |
| 9 | Talon Drilling Company | 37 | 63 | 1,966 |
| 10 | Brown Bros Drilling & Service | 29 | 52 | 5,569 |
| 11 | Mountain Research LLC | 27 | 27 | 1,243 |
| 12 | Marti Cascade | 24 | 26 | 342 |
| 13 | Morrison Excavating Morrison Excavating Inc. | 18 | 108 | 1,160 |
| 14 | Carroll Water Systems | 15 | 15 | 25 |
| 15 | C S Garber & Sons Inc. | 13 | 201 | 18,484 |
| 16 | Michael Barlow Well Drilling Service | 12 | 51 | 81 |
| 17 | Allied Well Drilling | 12 | 19 | 2,213 |
| 18 | Parratt-Wolff Inc. | 12 | 15 | 3,500 |
| 19 | G & R Westbrook Well Drilling Inc. | 10 | 1,137 | 2,921 |
| 20 | Summit Drilling LLC | 5 | 47 | 1,492 |
| 21 | Mark Irvin Mark Irvin-Wilson Well Drilling LLC | 5 | 28 | 497 |
| 22 | Kodiak Field Services | 5 | 5 | 1,705 |
| 23 | Accell Inc. | 5 | 5 | 116 |
| 24 | David Kelly | 4 | 67 | 135 |
| 25 | Funks Drilling Inc. | 3 | 39 | 2,469 |
| 26 | Patrick Ferris Company LLC | 3 | 3 | 27 |
| 27 | B. L. Myers Bros OF MD,LLC | 2 | 222 | 12,524 |
| 28 | A C Reider Inc. | 1 | 2,151 | 2,336 |
| 29 | Frank Frank Wilson JR Well Drilling | 1 | 31 | 1,417 |
| 30 | Adams Well Drilling | 1 | 28 | 617 |
| 31 | G S Fleese Drillin | 1 | 8 | 248 |
| 32 | Walters Well Drilling LLC | 1 | 1 | 791 |
| 33 | Randler's Well Drilling Inc. | 1 | 1 | 1,121 |
| 34 | David Kohler | — | 2,467 | 2,854 |
| 35 | J W Willwert Drilling | — | 1,966 | 2,239 |
| 36 | Young Bros | — | 1,535 | 1,546 |
| 37 | John Thran | — | 1,320 | 2,266 |
| 38 | R E Jackson Well Drilling | — | 1,080 | 1,218 |
| 39 | Michael J Kohler Inc. | — | 848 | 1,206 |
| 40 | Grandview Acres | — | 572 | 618 |
| 41 | J & J Well Drilling | — | 550 | 843 |
| 42 | York Drilling Company Inc. | — | 342 | 381 |
| 43 | Mummert & Sterner | — | 282 | 301 |
| 44 | Harrisburg's Kohl Bros Inc. | — | 259 | 2,819 |
| 45 | Edgar E Urey | — | 258 | 266 |
| 46 | Chapman Construction Inc. | — | 199 | 209 |
| 47 | Leon K Sunday | — | 154 | 906 |
| 48 | William C James | — | 142 | 142 |
| 49 | C E Sunday & Son Water Well Drilling | — | 139 | 1,452 |
| 50 | David W Mccabe Well Drilling | — | 137 | 138 |
| 51 | Weldo W Funt | — | 101 | 384 |
| 52 | Cekovich Well Drilling | — | 94 | 943 |
| 53 | Dale A Thomas & Sons Drilling Co. | — | 92 | 114 |
| 54 | Whislers Well Drilling Inc. | — | 91 | 1,819 |
| 55 | Paul E Kohler | — | 73 | 83 |
| 56 | Kohler Drilling Inc. | — | 59 | 65 |
| 57 | Gurvis Gurvis Jones Well Drilling, Inc. | — | 47 | 93 |
| 58 | L G Hetager Drilling Inc. | — | 32 | 600 |
| 59 | Water Well Drillers Licensing--Topo Geo | — | 29 | 732 |
| 60 | Barber Brothers Water Well Drilling Inc. | — | 25 | 28 |
| 61 | George M Brillhart | — | 24 | 26 |
| 62 | Handex Consulting & Remediation, LLC | — | 18 | 575 |
| 63 | Aaa Quality Wells & Pumps Inc. | — | 17 | 265 |
| 64 | Etnoyer Well Drilling | — | 16 | 404 |
| 65 | Geo-Environmental Drilling Co. Inc. | — | 15 | 3,228 |
| 66 | Perry County Water Well Drilling | — | 14 | 950 |
| 67 | Marcor Environmental Service Inc. | — | 14 | 67 |
| 68 | Green Mountain Construction & Equip Corp | — | 13 | 26 |
| 69 | Shiffer Drilling, Inc. | — | 11 | 904 |
| 70 | Gill Rock Drill Co. Inc. | — | 10 | 114 |
| 71 | Mcginnis Drilling | — | 8 | 67 |
| 72 | IT Environmental Inc. | — | 7 | 131 |
| 73 | Gilbert R Zechman | — | 6 | 1,635 |
| 74 | H K Honberger & Son | — | 6 | 414 |
| 75 | Petersheim Brothers H20,LLC | — | 5 | 8,096 |
| 76 | Kohl Bros., Inc. | — | 5 | 2,398 |
| 77 | Johnson Drilling | — | 5 | 512 |
| 78 | Gayman Well Drilling | — | 5 | 205 |
| 79 | Halls Well Drilling | — | 5 | 102 |
| 80 | Groundwater Technology | — | 5 | 75 |
| 81 | Bassett Environmental Associates, Inc. | — | 5 | 73 |
| 82 | Chesapeake Geosystems Inc. | — | 5 | 54 |
| 83 | W H Wissler Drilling | — | 5 | 46 |
| 84 | Fisher's Well Drilling | — | 4 | 551 |
| 85 | Martin T Fischer | — | 4 | 301 |
| 86 | Roger Leeds Well Drilling | — | 4 | 298 |
| 87 | Penners Well Drilling | — | 4 | 180 |
| 88 | Denis H Woodward, Inc. | — | 4 | 99 |
| 89 | Layne Christensen Company | — | 4 | 44 |
| 90 | Alexander Macphee--Cvm Industries | — | 3 | 495 |
| 91 | Carson Water Well Inc. | — | 3 | 1,749 |
| 92 | R And R Garber Inc. | — | 3 | 732 |
| 93 | George E Small | — | 3 | 76 |
| 94 | Duane Moyer Well Drilling | — | 2 | 11,486 |
| 95 | Tri-State Drilling | — | 2 | 604 |
| 96 | Merle L Gayman | — | 2 | 821 |
| 97 | J Karp & Sons, Inc. | — | 2 | 397 |
| 98 | Reith Geothermal Energy Inc. | — | 2 | 153 |
| 99 | Fehr's Well Drilling | — | 2 | 62 |
| 100 | Sjb Services, Inc. | — | 2 | 44 |
| 101 | Phares Fry Well Drilling & Pump Svc Inc. | — | 1 | 5,909 |
| 102 | Chris Cook - C W Cook, Inc. | — | 1 | 274 |
| 103 | Bucks County Well Drilling, Inc. | — | 1 | 3,006 |
| 104 | Martin's Well Drilling | — | 1 | 1,001 |
| 105 | Hermann Drilling Co. | — | 1 | 597 |
| 106 | Eldon E Funk | — | 1 | 581 |
| 107 | Andrew Andrew Shoop Well Drilling | — | 1 | 575 |
| 108 | Anderson Well Drilling & Pump Sales | — | 1 | 486 |
| 109 | Clair A Spahn | — | 1 | 384 |
| 110 | Leidos | — | 1 | 338 |
| 111 | J Reho & Sons, Inc. | — | 1 | 324 |
| 112 | Clearwater Drilling Company | — | 1 | 288 |
| 113 | Arnold Drilling LLC | — | 1 | 266 |
| 114 | Waterhouse Drilling | — | 1 | 204 |
| 115 | Roy Zimmerman | — | 1 | 173 |
| 116 | Mclaughlin Well Drilling | — | 1 | 148 |
| 117 | George Young | — | 1 | 107 |
| 118 | C & I Enterprises | — | 1 | 105 |
| 119 | Edsanclay Construction Co. | — | 1 | 97 |
| 120 | Bernard Marshall | — | 1 | 75 |
| 121 | Battali Well Drilling Inc. | — | 1 | 57 |
| 122 | Piper Construction Company | — | 1 | 53 |
| 123 | John S Funt | — | 1 | 49 |
| 124 | Paul L Wareham | — | 1 | 48 |
| 125 | James W Mccrory | — | 1 | 44 |
| 126 | Alfred Dailey | — | 1 | 41 |
| 127 | Urson Shellito | — | 1 | 40 |
| 128 | John E Hockenberry | — | 1 | 34 |
| 129 | Frank Wilson JR Well Drilling | — | 1 | 32 |