| Company | Location | Certifications | License # |
|---|---|---|---|
| A & M Septic And Excavating | Foristell, MO | Installer (Level Advanced) | 37238 |
| All Weather Sewer Service, Inc. | Desoto, MO | Installer (Level Basic) | 37120 |
| Askr Construction, Llc | Bonne Terre, MO | Installer (Level Advanced) | 32169 |
| Authority Plumbing And Drain | Warrenton, MO | Installer (Level Basic) | 39150 |
| Bloomsdale Excavating Company, Inc | Bloomsdale, MO | Installer (Level Basic) | 37242 |
| Cjc Concrete | Cadet, MO | Installer (Level Advanced) | 39046 |
| Dean Robinson Excavating Inc | Festus, MO | Installer (Level Advanced) | 30936 |
| Enterprise Sewer & Drain | St. Louis, MO | Installer (Level Basic) | 32157 |
| G&S Hardin Excavation Llc | Desoto, MO | Installer (Level Advanced) | 39078 |
| Gansner Excavating & Grading Llc | Festus, MO | Installer (Level Advanced) | 34297 |
| Grease Masters | St. Charles, MO | Installer (Level Basic) | 32409 |
| Hensley Excavating | Pevely, MO | Installer (Level Advanced) | 30502 |
| Hudson Plumbing Llc | Hillsboro, MO | Installer (Level Advanced) | 37232 |
| Integrated Facility Services | Fenton, MO | Installer (Level Advanced) | 33877 |
| Jeff Roderfeld Const. Llc | St. Charles, MO | Installer (Level Advanced) | 32371 |
| Jones Plumbing Service | De Soto, MO | Installer (Level Advanced) | 30923 |
| Joseph R Stabenow | Festus, MO | Installer (Level Advanced) | 36865 |
| Kuchar Trucking & Grading Inc. | Hillsboro, MO | Installer (Level Advanced) | 39313 |
| Lewis Plumbing Llc. | Hillsboro, MO | Installer (Level Advanced) | 37631 |
| M.D. Casey, Llc | Festus, MO | Installer (Level Advanced) | 37139 |
| Madonna'S Septic & Sewer Solutions | Hillsboro, MO | Installer (Level Advanced) | 37698 |
| Masters Excavating Llc | De Soto, MO | Installer (Level Advanced) | 38662 |
| Mr Rooter Stl | Fenton, MO | Installer (Level Basic) | 39322 |
| Mr. Rooter | Fenton, MO | Installer (Level Basic) | 39419 |
| Murphy Company Mechanical Contractors And Engineer | St. Louis, MO | Installer (Level Basic) | 39018 |
| Pinson Excavating | Cadet, MO | Installer (Level Basic) | 31383 |
| Prekins Branch Properties | Desoto, MO | Installer (Level Advanced) | 38071 |
| Ryan J Wallis | Bismark, MO | Installer (Level Advanced) | 36062 |
| Samuel Heating And Cooling | St. Louis, MO | Installer (Level Advanced) | 37690 |
| Schrum Masonry & Construction Inc | Desoto, MO | Installer (Level Advanced) | 31877 |
| Taylor Grading Llc | Festus, MO | Installer (Level Advanced) | 37626 |
| Tlm Contracting Llc | Desoto, MO | Installer (Level Advanced) | 30058 |
| Unlimited Landscape Maintenance | Festus, MO | Installer (Level Advanced) | 39383 |
| Wehmeyer Farms, Inc. | Moscow Mills, MO | Installer (Level Basic) | 37386 |
| Wm G Cocos Co Inc | St Louis, MO | Installer (Level Basic) | 37251 |
35 companies in the Missouri DHSS registered OWTS installer list are based in Jefferson County as of 2026-07-23. Companies based elsewhere in Missouri also commonly serve the county.
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