The Oklahoma Master Plumber Guide

Facts in this guide are drawn from the PSI Services LLC Candidate Information Bulletin for the Oklahoma Construction Industries Board (© 2025), read on September 30, 2026, and from the state rule that adopts the plumbing code — OAC 748:20-16-1, effective 14 September 2026. Oklahoma rules and bulletins change: always confirm against the current bulletin and the Board before you apply.

What Is the Oklahoma Plumbing Contractor License?

Plumbing licensing in Oklahoma runs through the Construction Industries Board (CIB), the state agency that licenses the construction trades, and the CIB contracts with PSI Services LLC to deliver its examinations. The bulletin for the plumbing trade publishes the Plumbing Contractor and Natural Gas examination — the credential this platform prepares you for — under a scope of work the bulletin states as the installation, repair and maintenance or extension of any plumbing system, including sanitary drainage waste and vents, water supply, plumbing fixtures and roof drains, and also the installation, maintenance or repair of gas piping, appliances, vents, flues, tanks and other related appurtenances in a supervised environment.

Two things about the Oklahoma plumbing track are worth knowing before you plan anything. First, the examination has a fuel gas component built into its name and its items: Fuel Gas is one of the ten published content areas and carries as many questions as water supply or drains and sewers. Second, the plumbing bulletin also publishes a separate Plumbing Business and Law examination — 50 questions in 120 minutes with a 75% (37 correct) pass line, also open book — covering bidding and estimating, project management and supervision, contracts and financial management. Which examinations your licence requires is a CIB question: confirm it with the Board before you register, so you do not prepare for half of the requirement.

If you pass the license exam, the Oklahoma State Construction Industries Board issues you a license. The exam vendor scores and reports; the Board licenses.

The Code the State Adopted, and the Edition the Bulletin Still Lists

Oklahoma is one of the states where the code of the state and the reference list of the bulletin have not moved at the same time. Both facts are published; here they are, side by side, as they stand.

• The state code is the 2024 edition. The Oklahoma Uniform Building Code Commission (OUBCC) adopted the International Plumbing Code, 2024 Edition (IPC 2024), first printing (June 2023), as amended and modified in the subchapter, as the statewide minimum code for commercial plumbing construction in the state — rule 748:20-16-1, effective 14 September 2026. The rule says more than that: the Commission through formal action expressly chose not to adopt the IPC 2021 for any purpose, and none of the IPC 2024 appendices were adopted. Errata published by the ICC for the IPC 2024 edition has not been reviewed or incorporated into the rules.
• The bulletin in force still lists the 2018 edition. The reference list of the Plumbing Contractor and Natural Gas examination names the International Plumbing Code, 2018 edition, with Oklahoma Revisions, and the International Fuel Gas Code, 2018 edition, with Oklahoma Revisions, among the materials allowed in the examination center.

That is the exam's edition lag, published — the same situation the bulletin describes for the state as a whole. What it means for you, practically: read the bulletin in force at your registration, because the reference list is also the list of what you may bring, and for code questions the examination is based only on the edition of the code book that is listed. If the bulletin you receive names the 2018 edition, you prepare and sit the 2018 edition; when the bulletin is revised, the weights and the areas stay where they are and only the editions move.

Exam Format: Open Book, 85 Questions, 180 Minutes

The Oklahoma Plumbing Contractor and Natural Gas examination is a computer-based examination delivered by PSI, open book, with the candidate's own references from the approved list. The bulletin publishes its format in one table — 85 questions, 75% passing, 64 correct answers, 180 minutes — and then publishes the topics area by area. At a glance:

Three details deserve to be read twice. First, this is a true open-book examination with your own materials — which makes preparation a physical task as well as an intellectual one, because the bulletin sets binding rules on how those references may be marked and bound. Second, the examination may also contain questions based on trade knowledge or general industry practices, the bulletin says, so the reference list is a floor rather than a ceiling on what can be asked. Third, later editions are allowed — except for the code: the bulletin states that except for code books, later editions of references are allowed in the test area, and that for code questions the examinations will be based only on the edition of the code book that is listed.

Official Content Outline: The Ten Areas of the Plumbing Examination

The bulletin publishes the examination as topic information with an item count per topic. The Plumbing Contractor and Natural Gas outline has ten areas, and they sum exactly to the 85 questions:

Topic names and item counts as published in the official PSI candidate bulletin for the Oklahoma Construction Industries Board (Plumbing Contractor and Natural Gas section). Sub-topics are the bulletin's own.

Read the weights as a study plan. Vents alone carries 13 questions — the single largest area on the examination, and more than the Safety and Traps areas combined. Below it sit four areas of 10: General Plumbing Knowledge and Regulations, Water Supply, Drains and Sewers, and Fuel Gas. Those five areas are 53 of the 85 questions — nearly two thirds of the examination. The plumbing contractor examination is not a code-recall test: with the references open on the desk, the marks go to the candidate who knows where the answer lives, and who has practised reading an isometric and sizing gas and water piping while the clock runs.

Reference Rules: What You May Bring, and How It Must Be Prepared

Because Oklahoma is open book with the candidate's own materials, the reference rules are part of the exam. The bulletin says candidates are responsible for bringing their own references to the examination center, and then sets the conditions:

• Before the session: reference materials may be highlighted, underlined and/or indexed prior to the examination session.
• During the session: references may not be written in prior to or during the examination session. A candidate caught writing in the references during the examination will have the references confiscated and will be reported to the department.
• Nothing extra: candidates are not permitted to bring in any additional papers with their approved references; any additional materials are removed and confiscated.
• Tabs: references may be tabbed or indexed with permanent tabs only. Temporary tabs such as Post-it notes are not allowed and must be removed before the exam begins.
• Downloaded references: if you download a reference from the internet, it must be spiral bound or hole-punched and placed in a binder, or stapled in the left-hand corner.
• Editions: except for code books, later editions of references are allowed in the test area. For code questions, the examination is based only on the edition of the code book that is listed.
• Tools on the desk: a silent, non-printing, non-programmable calculator is permitted, and a magnifying glass is provided on request.

Practical consequences for your preparation: build your reference set early, mark it in the way the bulletin allows, and rehearse finding answers under time pressure with exactly the books you will carry in. A candidate who prepares the code but not the reference set arrives unprepared for half the examination.

Score Reporting, Review and Administrative Notes

• Score reporting: your score is given to you immediately following completion of the examination. On screen, the score appears automatically at the end of the time allowed: if you pass, you immediately receive a successful notification; if you do not pass, you receive a diagnostic report indicating your strengths and weaknesses by examination type together with the score report. An unofficial score report is also printed at the examination site.
• Duplicate score reports: you may request a duplicate score report after your examination by emailing PSI's score-report address, as the bulletin instructs.
• Comments and review: while taking the examination, examinees have the opportunity to provide comments on any questions. The bulletin states that the Board may re-evaluate candidates' results and adjust them accordingly, and calls this the only review of the examination available to candidates.
• What is not published in this guide: the examination fee in effect and the rescheduling or cancellation conditions are administrative terms that change, and this guide does not restate them — read them in the current bulletin and on the PSI program page before you book.

How to Prepare

1. Confirm the licence track with the CIB first. The plumbing examination and the separate Plumbing Business and Law examination may both sit in your path; the Board — not the vendor — decides what your licence requires. Settle that before you buy a single study hour.
2. Read the bulletin in force at registration for the code edition. The state adopted the IPC 2024 (OAC 748:20-16-1, effective 14 September 2026) while the bulletin still lists the IPC 2018 with Oklahoma Revisions. The edition named in your bulletin is both what you study and what you may bring.
3. Build and prepare the reference set. Highlight, underline and index before the session, use permanent tabs only, remove anything temporary, and bind downloaded material the way the bulletin requires. Then rehearse with that exact set.
4. Drill the ten areas at their published weights. Vents (13) is the biggest single area; General Plumbing Knowledge and Regulations (10), Water Supply (10), Drains and Sewers (10) and Fuel Gas (10) follow. Practice questions should mirror those weights.
5. Treat fuel gas and isometrics as exam skills, not side topics. Ten fuel-gas items and seven isometric items are 17 of the 85 questions, and both reward working through the code with a pencil rather than skimming it.
6. Simulate the real thing. Full-length, timed runs of 85 questions in 180 minutes, open book with your prepared references, aiming comfortably past the 64-correct line. MasterPlumberPractice reproduces the Oklahoma format in a full-length simulation so the real examination feels like a repeat.

MasterPlumberPractice is built for exactly this examination: practice questions aligned to the Oklahoma blueprint, theory covering the IPC and the fuel gas code, and full-length timed simulations in the published format with an AI tutor to close your weak areas. Start with free practice questions to feel the format, work through our plumbing code theory guides, and create a free account to track your scores as you go.

Frequently Asked Questions

Ready to Earn the Oklahoma License?

Oklahoma hands you the code and asks you to use it: 85 questions, 180 minutes, 64 correct to pass, with your own prepared references on the desk. The candidates who pass are the ones who have rehearsed with those exact books and who know the Vents area cold. Confirm your licence track and the edition in force with the CIB, then build your prep around the published blueprint: study the code with our plumbing code theory guides, try free practice questions, register free and see the all-inclusive pricing — one subscription covering the full Oklahoma blueprint, so you never buy prep piece by piece.