| Company | Location | Certifications | License # |
|---|---|---|---|
| Anderson Construction Llc | Stockton, MO | Installer (Level Advanced) | 39318 |
| Ayers Construction | Lamar, MO | Installer (Level Advanced) | 39375 |
| Ayers Construction | Lamar, MO | Installer (Level Advanced) | 39395 |
| Blackwater Septic & Sewer | Rich Hill, MO | Installer (Level Basic) | 38900 |
| Brian Bennett N Son | Oronogo, MO | Installer (Level Basic) | 39319 |
| C&L Grease And Wastewater Services Llc | Carterville, MO | Installer (Level Advanced) | 38000 |
| Carter'S Plumbing | Oronogo, MO | Installer (Level Advanced) | 39448 |
| Charity L Schneickert | Joplin, MO | Installer (Level Basic) | 38537 |
| Dawson Renfro | — | Installer (Level Advanced) | 39463 |
| Drew Thomas Excavating | Carthage, MO | Installer (Level Basic) | 37017 |
| E 2 Dirt Service | Carthage, MO | Installer (Level Advanced) | 36666 |
| Eddie Mcdowell Excavation Llc | Lamar, MO | Installer (Level Basic) | 38878 |
| Ez Dirt Services | Eldorado Springs, MO | Installer (Level Basic) | 37825 |
| Foster'S Plumbing | El Dorado Springs, MO | Installer (Level Basic) | 39422 |
| Hilltop Plumbing & Excavating | Walker, MO | Installer (Level Basic) | 39062 |
| Hk Excavation Llc | Neosho, MO | Installer (Level Advanced) | 37294 |
| Justin Colvin Excavating Llc | Stockton, MO | Installer (Level Advanced) | 39071 |
| Kb Mechanical Services Llc | Greenfield, MO | Installer (Level Advanced) | 38359 |
| Lane Wilson | Nevada, MO | Installer (Level Advanced) | 39560 |
| Lathrop Excavating | Lamar, MO | Installer (Level Advanced) | 34671 |
| M4 Excavating | El Dorado Springs, MO | Installer (Level Basic) | 38938 |
| Mast Excavating | Sarcoxie, MO | Installer (Level Basic) | 36837 |
| Matt Nichols Construction Llc | Carthage, MO | Installer (Level Advanced) | 39432 |
| Mccord Excavating Llc | Moundville, MO | Installer (Level Advanced) | 36849 |
| Nevada Plumbing, Septic & Sewer Llc | Neveda, MO | Installer (Level Advanced) | 36001 |
| Patterson Excavating | Lockwood, MO | Installer (Level Advanced) | 38764 |
| Premier Dirt & Landscape | Carl Jct., MO | Installer (Level Advanced) | 39312 |
| Prodrain | El Dorado Springs, MO | Installer (Level Basic) | 39435 |
| R. L Boyd Construction | Greenfield, MO | Installer (Level Advanced) | 30354 |
| R&R | Lamar, MO | Installer (Level Basic) | 39556 |
| S.V Construction Builders Llc | El Dorado Springs, MO | Installer (Level Basic) | 39393 |
| Top Notch Excavating, Llc | Greenfield, MO | Installer (Level Basic) | 31344 |
| Wagoner Services | Stockton, MO | Installer (Level Basic) | 37412 |
| Willis Excavating | Carthage, MO | Installer (Level Advanced) | 33708 |
| Zach Erwin Construction Inc | Nevada, MO | Installer (Level Advanced) | 36836 |
35 companies in the Missouri DHSS registered OWTS installer list are based in Barton County as of 2026-07-23. Companies based elsewhere in Missouri also commonly serve the county.
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