Missouri Plumbing Permit Requirements

Permits Are Required for Most Plumbing Work

Under locally adopted codes in Missouri, a permit is required to install, enlarge, alter, repair, remove, or replace any plumbing or fuel gas system. Only licensed contractors or master plumbers can pull permits — journeymen perform the work but cannot initiate the permit process on their own.

The permit is jurisdiction-specific. A permit from Kansas City covers Kansas City projects only. Work across the county line requires a separate permit from that jurisdiction's building department.

What Is Exempt

Minor ordinary repairs are typically exempt from permitting, though the exact definition varies by jurisdiction. Common exemptions across most Missouri municipalities include:

• Replacing faucet washers
• Fixing minor leaks involving less than 12 inches of exposed pipe
• Swapping residential garbage disposals in the same location
• Replacing fixture trim (handles, escutcheons)

Anything beyond cosmetic repairs — rerouting drainage, adding fixtures, replacing water heaters, installing gas lines — requires a permit. When in doubt, call the local building department before starting work. The cost of a phone call is negligible compared to a stop-work order.

Homeowner Exemptions

Most Missouri jurisdictions allow owner-occupants to perform plumbing work on their own primary residence, subject to local permit and inspection requirements. This exemption does not apply to rental properties, commercial buildings, or multi-family structures.

Inspection Stages

Once a permit is issued, work proceeds through three inspection milestones:

Ground rough — Before pouring concrete. The inspector verifies below-slab drainage layout, pipe placement, and proper fall.

Rough-in — Before closing walls. Supply lines, DWV (drain-waste-vent) piping, and gas lines are pressure-tested and visually inspected. Air or water pressure testing is required on both supply and DWV systems.

Final — After trim and fixtures are set. The inspector confirms proper fixture operation, trap seals, vent terminations, and gas appliance connections.

Failing any stage means corrections before the project can advance. Each re-inspection may carry an additional fee.

Permit Costs by Jurisdiction

Permit fee schedules are set locally and updated periodically:

• St. Louis County: Fee schedule updated annually under Ordinance 29445 (effective July 31 each year)
• Springfield: Permit fees are project-based, with a double-fee-plus-$200 penalty for work started without a permit
• St. Charles County: Fees set under the county building code, Section 106

Exact fees depend on the scope of work — new construction plumbing costs more to permit than a water heater replacement. Contact the local building department for current fee schedules before quoting a project.

Gas Work Requires Extra Credentials

Working on gas lines — water heaters, furnaces, gas piping — typically requires a specialized credential beyond the standard plumbing license. In St. Charles County and Jefferson City, contractors must pass an exam that includes gas certifications (ICC G27 Master Plumber with Gas or G28 Journeyman with Gas) to pull permits for fuel gas work.

Backflow prevention device installation and lawn irrigation system connections also require plumbing permits, with tested assemblies verified by a certified tester and results filed with the local water authority.

The Missouri Plumber License Guide covers permit requirements and inspection protocols across seven Missouri jurisdictions, including which gas endorsements each board requires.

See more Missouri guides →