| Company | Location | Certifications | License # |
|---|---|---|---|
| About Plumbing Inc | Barnhart, MO | Installer (Level Basic) | 38593 |
| Jokerst Paving & Contracting, Inc | Festus, MO | Installer (Level Advanced) | 37319 |
| Missouri Plumbing Contractors | Kirkwood, MO | Installer (Level Advanced) | 37006 |
3 companies in the Missouri DHSS registered OWTS installer list are based in St Louis County as of 2026-07-23. Companies based elsewhere in Missouri also commonly serve the county.
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