| Company | Location | Certifications | License # |
|---|---|---|---|
| A & B Plumbing & Heating, Inc. | Park Hills, MO | Installer (Level Advanced) | 32033 |
| A R C Grading, Llc | Moscow Mills, MO | Installer (Level Advanced) | 36003 |
| Aa Quick Plumbing & Sewer Service Of Jefferson County, Inc. | Dittmer, MO | Installer (Level Advanced) | 32003 |
| Aa Quick Sewer Service | Dittmer, MO | Installer (Level Advanced) | 35231 |
| Affordable Plumbing Llc | Hermann, MO | Installer (Level Advanced) | 39349 |
| Andrew Noack | — | Installer (Level Basic) | 39019 |
| B Green Plumbing & Drain Cleaning Llc | Warrenton, MO | Installer (Level Advanced) | 37819 |
| B. Green Plumbing & Drain Cleaning, Llc | Warrenton, MO | Installer (Level Advanced) | 37818 |
| Ballmann Earthworks | Augusta, MO | Installer (Level Basic) | 39387 |
| Baner Excavation | Hillsboro, MO | Installer (Level Advanced) | 30489 |
| Bdg Contracting Inc | St. Louis, MO | Installer (Level Advanced) | 38233 |
| Big D Pipe Llc | St Charles, MO | Installer (Level Basic) | 38376 |
| Bigley Construction | Union, MO | Installer (Level Advanced) | 31237 |
| Bill Martin Construction Llc | Eureka, MO | Installer (Level Advanced) | 30985 |
| Bill Williams Construction | Cedar Hill, MO | Installer (Level Advanced) | 37837 |
| Blackwood Plumbing | Warrenton, MO | Installer (Level Advanced) | 39137 |
| Bob'S Plumbing Company | St. Clair, MO | Installer (Level Advanced) | 30540 |
| Bobs Plumbing Company | Saint Clair, MO | Installer (Level Advanced) | 35522 |
| Bradford Excavating | Hillsboro, MO | Installer (Level Advanced) | 30935 |
| Brian Unnerstall | Villa Ridge, MO | Installer (Level Basic) | 31426 |
| Brighthouse Plumbing | Fenton, MO | Installer (Level Basic) | 38977 |
| Brown Service Co | High Ridge, MO | Installer (Level Advanced) | 30037 |
| Brown Tractor Service Llc | Bloomsdale, MO | Installer (Level Advanced) | 30402 |
| Brute Force Hauling And Excavating Llc | Washington, MO | Installer (Level Advanced) | 39508 |
| C & H Plumbing Company | St Louis, MO | Installer (Level Basic) | 34746 |
| Chad Queen Contracting Services, Llc | Desoto, MO | Installer (Level Advanced) | 31214 |
| Chartette Creek Excavating Llc | Marthasville, MO | Installer (Level Advanced) | 39311 |
| Commercial Drain & Sewer Cleaning Inc | Arnold, MO | Installer (Level Basic) | 38278 |
| Commercial Drain & Sewer Cleaning, Inc. | Arnold, MO | Installer (Level Advanced) | 31079 |
| Dempsey Investment Llc | Jonesburg, MO | Installer (Level Basic) | 39417 |
| Djm Ecological Services Inc. | St. Louis, MO | Installer (Level Advanced) | 38234 |
| Dobsch Construction Llc | Washington, MO | Installer (Level Basic) | 39136 |
| E&J Siteworks Llc | Dittmer, MO | Installer (Level Advanced) | 38330 |
| Earthworx Excavating & Bobcat Services, Inc | Villa Ridge, MO | Installer (Level Advanced) | 36286 |
| Edward'S Construction | Washington, MO | Installer (Level Advanced) | 35706 |
| Edward'S Construction | Washington, MO | Installer (Level Advanced) | 31976 |
| Elbert Earthworks | Berger, MO | Installer (Level Basic) | 39274 |
| Erbe Construction Llc | Silex, MO | Installer (Level Advanced) | 39010 |
| Eric Ankelman | — | Installer (Level Basic) | 38868 |
| Ethan Ford | — | Installer (Level Advanced) | 39450 |
| Flowmasters Plumbing Llc | Overland, MO | Installer (Level Advanced) | 37247 |
| Gerling Excavating & Const | Berger, MO | Installer (Level Advanced) | 31649 |
| Greater Missouri Homes Llc | Augusta, MO | Installer (Level Basic) | 38776 |
| H.S. Plumbing Llc | Troy, MO | Installer (Level Advanced) | 37814 |
| Integrity Septic And Sewer Llc | Pacific, MO | Installer (Level Advanced) | 30498 |
| Intelligent Plumbing Solutions | New Melle, MO | Installer (Level Advanced) | 39398 |
| J-L Page Excavation | Rhineland, MO | Installer (Level Advanced) | 35008 |
| J&B Ruessler Septic | Hillsboro, MO | Installer (Level Basic) | 37965 |
| Jake'S Backhoe And Construction | Hermann, MO | Installer (Level Advanced) | 30262 |
| Jarvis Excavating Llc | Owensville, MO | Installer (Level Advanced) | 36008 |
| Jesse Kleinheider Contracting Llc | Washington, MO | Installer (Level Advanced) | 37791 |
| Jl Hicks Services, Llc | Desoto, MO | Installer (Level Advanced) | 37361 |
| John'S Excavating & Contractor | Cedar Hill, MO | Installer (Level Advanced) | 31644 |
| Kelpe Contracting Inc | Wildwood, MO | Installer (Level Advanced) | 32263 |
| Klemme'S Backhoe Service | Wentzville, MO | Installer (Level Basic) | 38703 |
| Kolb Grading Llc | St. Charles, MO | Installer (Level Basic) | 37514 |
| Larry'S Landscaping | Barnhart, MO | Installer (Level Advanced) | 31259 |
| Lcg Legacy Contracting Group | Pacific, MO | Installer (Level Advanced) | 38186 |
| Lhs Hauling & Grading | Warrenton, MO | Installer (Level Advanced) | 30884 |
| Luke Robinson | — | Installer (Level Basic) | 38948 |
| Mathena Excavating | Washington, MO | Installer (Level Basic) | 39284 |
| Merlo Plumbing, Co., Inc | St. Louis, MO | Installer (Level Basic) | 32301 |
| Moore Works Llc | — | Installer (Level Basic) | 38536 |
| Mots Excavation Llc | Hillsboro, MO | Installer (Level Basic) | 39593 |
| Mr Rooter Plumbing Llc | Saint Clair, MO | Installer (Level Advanced) | 32250 |
| No Limits Excavating Llc | Villa Ridge, MO | Installer (Level Basic) | 39142 |
| Oberkramer Septic Solutions, Llc | High Ridge, MO | Installer (Level Basic) | 38944 |
| Parker Petroleum Sales & Service | Troy, MO | Installer (Level Basic) | 37974 |
| Professional Onsite Installations | Hillsboro, MO | Installer (Level Advanced) | 31147 |
| Pruessner Contracting Llc | New Haven, MO | Installer (Level Advanced) | 37790 |
| R E Signature Homes | Ste Genevieve, MO | Installer (Level Basic) | 30724 |
| Rich Gullet & Sons | Pacific, MO | Installer (Level Advanced) | 31145 |
| Schlett Construction | Barnhart, MO | Installer (Level Advanced) | 30545 |
| Septic Solutions | House Springs, MO | Installer (Level Advanced) | 39532 |
| Show Me Soils | Lonedell, MO | Installer (Level Advanced) | 36886 |
| Sk Hardin Construction | Desoto, MO | Installer (Level Advanced) | 39079 |
| St.Louis Excavation | Saint Clair, MO | Installer (Level Basic) | 38412 |
| Starks Excavating Llc | Warrenton, MO | Installer (Level Advanced) | 30092 |
| Starks Excavating Llc | Warrenton, MO | Installer (Level Basic) | 38526 |
| Superier Heating & Cooling | Lake St. Louis, MO | Installer (Level Basic) | 38556 |
| Superior Sewer Co | St. Louis, MO | Installer (Level Basic) | 38827 |
| Superior Sewer Co | Sunset Hills, MO | Installer (Level Advanced) | 36774 |
| Tim Bennett Plmbing, Llc | Imperial, MO | Installer (Level Advanced) | 30495 |
| True Form Contracting | Robertsville, MO | Installer (Level Advanced) | 39097 |
| Valle Land Development Llc | Valles Mines, MO | Installer (Level Basic) | 39377 |
| Valle Land Development, Llc | Valles Mines, MO | Installer (Level Basic) | 39374 |
| Weber Construction Llc | Union, MO | Installer (Level Advanced) | 37126 |
| Wiggs Plumbing Llc | — | Installer (Level Basic) | 38899 |
| William E Courtway/Redline Junk Removal & Dumpster | Cadet, MO | Installer (Level Advanced) | 39030 |
| Wm Mueller Trenching And Excavating | St. Charles, MO | Installer (Level Advanced) | 38369 |
| X-L Contracting | Saint Peters, MO | Installer (Level Basic) | 32240 |
91 companies in the Missouri DHSS registered OWTS installer list are based in Franklin County as of 2026-07-23. Companies based elsewhere in Missouri also commonly serve the county.
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