Requirements, license levels, and the issuing authority, sourced from Missouri's official board.
The fifteen-thousand-inhabitant threshold in RSMo 341.010 is a real statutory line that national summaries almost never mention, and it is the first thing to check before quoting work in Missouri.
| Requirements | MISSOURI SETS THE RULE BY POPULATION, WHICH IS UNUSUAL AND VERY SPECIFIC. Under RSMo 341.010 and following, any person working at the business of plumbing, as either master plumber or journeyman plumber, IN CITIES OR TOWNS OF FIFTEEN THOUSAND OR MORE INHABITANTS must first receive a certificate in accordance with those sections. Below that population threshold the statute does not require the certificate. SO THE ANSWER DEPENDS ON THE SIZE OF THE TOWN. A plumber working in Kansas City, St. Louis, Springfield or Columbia needs the certificate; the same plumber working in a town of 8,000 does not, as a matter of state law, though the municipality may still have its own ordinance. THE CERTIFICATE IS ADMINISTERED LOCALLY. There is no state plumbing board issuing a single card; the qualifying municipalities run the examinations and hold the registers, so the requirements and fees differ between them. PRACTICAL CONSEQUENCE: check the population of the jurisdiction, then check that jurisdiction's board. A plumber working across a metropolitan area may hold several certificates. |
| Reciprocity | Not applicable at state level. Missouri has no state plumbing board, so recognition of another jurisdiction's certificate is decided by each qualifying municipality, and varies between them. |
| Renewal | Set by the certifying municipality. There is no state renewal and no state continuing-education requirement. |
| Notes | The fifteen-thousand-inhabitant threshold in RSMo 341.010 is a real statutory line that national summaries almost never mention, and it is the first thing to check before quoting work in Missouri. |
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Sources: pr.mo.gov, pr.mo.gov, revisor.mo.gov, revisor.mo.gov. Always confirm current requirements with the issuing authority.
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