Plumbing and HVAC rules in Missouri

What the state says about plumbing and heating and cooling work, with the page each rule comes from. It's a summary of the published rules, not legal advice, and your city or county can have rules of its own.

Checked September 23, 2026

Plumbing licensing

Missouri has no state plumbing license. State law sets qualifications for plumbers in larger cities and counties that license them locally, such as Kansas City and St. Louis County.^{1, 2, 3}

Heating and cooling licensing

Missouri has no state license for heating and cooling work. Ask your city or county whether it licenses heating and cooling contractors.⁴

Plumbing and mechanical codes

Your local building department can tell you which plumbing and mechanical codes apply where you live.

Permits to replace a water heater, furnace or AC

Ask your local building department whether replacing a water heater, furnace or AC needs a permit where you live.

Backflow testing

In Missouri, reduced pressure and double check backflow assemblies must be tested every year by a certified tester.⁵

Sources

What plumbing and HVAC work costs in Missouri

Published national ranges for plumbing, water heater, sewer, AC, heat pump and furnace jobs, and a planning estimate for your own job.

Plumbing, heating and cooling costs in Missouri

Contractors in Missouri

257 plumbers and heating and cooling contractors are listed in Missouri. 133 hold an active USDOT registration. Browse them by county, or ask for quotes and we'll pass your job to contractors near you.

Cite this page

“Plumbing and HVAC rules in Missouri.” PlumbingInformationSite.com, updated September 27, 2026. https://plumbinginformationsite.com/mo/rules/