St. Louis Plumbing: Licensing, Permits & Water

The Board of Examiners for Plumbers and Drainlayers, a mayor-appointed panel that includes a Master Plumber chair, a master drainlayer, a journeyman and a certified plumbing designer, sets the tests and the passing grades for every trade rank in the city and meets monthly to approve apprentices and hear complaints. Separately and practically, the Building Division's Plumbing Section certifies the plumbing contractors, and it is that contractor credential a permit application stands on.

• Authority. City of St. Louis Board of Examiners for Plumbers and Drainlayers; permits and contractor certification run through the Building Division, Plumbing Section
• Structure. The city board writes and grades the examinations for master plumbers, master drainlayers and journeyman plumbers, approves apprentice applications, and hears complaints; a separate Plumbing Contractor credential from the Building Division is what actually pulls permits
• Worth knowing. Missouri has no statewide plumber license, so the City of St. Louis credential is the one that matters here: the city's published requirements issue plumbing permits to city-certified plumbing contractors, and the examiner board itself is chaired by a city-certified Master Plumber.

Checked against the official source, September 2026: www.stlouis-mo.gov.

Unlike its own electrical rules, which give an owner-occupant a narrow self-permit test, the city's plumbing permit pages name exactly one path: a city-certified plumbing contractor applies, through the STL City Permits dashboard or in person at Room 425 of City Hall. For a homeowner that makes the pre-hire check unambiguous: the person pulling your permit must hold the city's contractor certification, and the same dashboard that filed the permit schedules the inspections.

• Permit office. Building Division, Plumbing Section (Department of Public Safety), Room 425, City Hall, or online through the STL City Permits portal
• Homeowner rule. The city publishes no homeowner self-permit path for plumbing: the plumbing-permit page lists a city Plumbing Contractor credential as a requirement, and the owner-exception the city does publish (a short code test for an owner-occupied single-family dwelling) appears only on the electrical permit page. Plumbing permits go to city-certified contractors.
• Process. Online applications run through the contractor's dashboard on the STL City Permits site, with feedback by email, and most are approved within one to three business days. Walk-in permits are handled at Room 425, City Hall during weekday business hours, and approved contractors print the permit and schedule inspections from the same dashboard.

Checked against the official source, September 2026: www.stlouis-mo.gov.

The Water Division treats river water with precipitative softening, which is why a city drawing on the Missouri and Mississippi delivers water in the hard band at the tap: the 2021 through 2025 consumer confidence reports average 129 to 140 mg/L. The figure shown here, 129 mg/L, is the 2025 report's annual average, the newest single figure the utility publishes alongside its yearly range. Two city programs matter to older housing stock: a lead service line inventory of roughly 113,000 lines with a public address lookup, and the Sewer Lateral Repair Program, which uses a small per-property tax fee to fix broken laterals under the public right of way. Plumbing work follows the 2021 Uniform Plumbing Code, adopted by city ordinance in 2023.

• Utility. City of St. Louis Water Division (Department of Public Utilities)
• Supply source. Two rivers, two plants: the Howard Bend plant draws the Missouri River; the Chain of Rocks plant sits on the Mississippi just below the confluence, where the intake water is still mostly Missouri River water, since the two rivers have not yet fully mixed
• Hardness. 129 mg/L (≈7.5 gpg), hard; utility CCR, 2025 annual average, 2025

Utility information: www.stlouis-mo.gov. The hardness figure is the same record shown on the Missouri page.

• Drain Cleaning
• Water Heater Repair

  Precipitative softening at the two river plants keeps St. Louis heater scale moderate.

• Sewer Line Repair

  Broken laterals under the public right of way fall to the city's Sewer Lateral Repair Program, funded by a small tax fee on residential properties of six units or fewer.

• Septic Tank Pumping
• Leak Detection & Repair
• All services →

This page explains how plumbing is regulated in St. Louis; it is not a provider directory. For the job itself, describe the problem and your ZIP: a license-checked plumber who covers St. Louis gets the details and contacts you with next steps and a quote.

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