TX-MP Exam Domains 2026: Complete Guide to All 12 Content Areas

How the TX-MP Exam Is Structured

Before breaking down the content areas, it helps to understand the exam format itself. The Texas Master Plumber License Exam is administered by Pearson VUE on behalf of the Texas State Board of Plumbing Examiners (TSBPE). According to the August 2025 Pearson handbook, the current exam consists of 308 items delivered over 360 minutes at authorized Pearson VUE test centers, with an optional additional 30-minute clock-stopped break available to candidates who need it. A passing score is 70%.

Personal books, handwritten notes, and outside references are not allowed in the testing room. Instead, candidates use program-supplied references and calculation resources provided at the center. That distinction matters when you plan your prep: you are not memorizing every number in every sizing table, you are learning how to locate and apply information correctly under timed conditions. For a full breakdown of how these mechanics translate into a study approach, see the TX-MP Study Guide 2026: How to Pass on Your First Attempt.

The 12 Content Areas, Explained

The 12 domains tied to the Texas Master Plumber License Exam trace back to the Board-linked Master Plumber Examination Review Course, which organizes preparation into knowledge subjects, sizing-chart tasks, and a capstone design exercise. Here is the full list of domains as named in that review material:

1. Plumbing Codes
2. Plumbing Codes, specific to water heater installation
3. Occupational Safety and Health Administration (OSHA) Code Federal Regulations
4. Texas Accessibility Standards (TAS), as they apply to plumbing fixture installations
5. Liquefied Petroleum Gas piping installation
6. Plumbing Related Mathematics
7. Plumbing License Law and Board Rules
8. Fuel Gas Pipe Sizing chart
9. Water Pipe Sizing chart
10. Gas Fueled Appliance Vent Sizing chart
11. Drainage System Pipe Sizing chart
12. Design of a three-story sanitary drainage and vent system for sixteen (16) plumbing fixtures

Notice the pattern: the first seven are knowledge-based subjects, the next four are hands-on sizing-chart tasks, and the twelfth is a comprehensive design problem that pulls everything together. That structure is the backbone of a smart study sequence, and it's worth revisiting each time you sit down to review - bookmark this page as your reference back to TX-MP Exam Domains 2026: Complete Guide to All 12 Content Areas whenever you need the full list again.

The Seven Knowledge Subjects

The first group of domains tests your command of codes, regulations, and math that a Master Plumber applies daily. These are conceptually distinct from one another, so grouping your study by subject - rather than cramming everything together - tends to pay off.

The Four Sizing-Chart Tasks

The next four domains shift from recall to applied chart-reading and calculation. These tasks reward practice with the actual reference materials over pure memorization.

• Domain 8 - Fuel Gas Pipe Sizing chart: Sizing gas piping runs based on load and length using a fuel gas sizing chart.
• Domain 9 - Water Pipe Sizing chart: Determining water supply pipe sizes based on fixture demand and system layout.
• Domain 10 - Gas Fueled Appliance Vent Sizing chart: Sizing venting for gas-fueled appliances correctly to match appliance input and vent configuration.
• Domain 11 - Drainage System Pipe Sizing chart: Sizing drainage piping based on fixture units and drainage fixture unit tables.

Domain 12: The Three-Story Design Problem

Domain 12 is the capstone: design of a three-story sanitary drainage and vent system for sixteen plumbing fixtures. This domain synthesizes nearly everything from the sizing-chart domains and the math domain into a single, multi-step design exercise.

Because it draws on drainage sizing, vent sizing, and applied math simultaneously, most candidates find it efficient to master Domains 6, 9, and 11 first, then treat Domain 12 as an integration exercise rather than new material. If you're trying to gauge how much of a stretch this domain will feel relative to the rest of the exam, our breakdown on How Hard Is the TX-MP Exam? Complete Difficulty Guide 2026 walks through where candidates tend to spend the most review time.

Why the Old 210-Question Breakdown Doesn't Apply Anymore

If you come across the Board-linked Master Plumber Examination Review Course itself, you'll notice it carries a February 2013 footer and references the 2018 IPC/IFGC or 2018 UPC codes. That document also lists a 210-question breakdown across its topics. It's important to be precise about what that means: the 12 domain names and study components above are still accurate and useful as preparation topics, but the 210-question count and any implied weighting from that legacy document are not the current 308-item examination described in the August 2025 Pearson handbook, and they do not represent a current weighted blueprint.

In practical terms, treat the 12 domains as your topic checklist - the "what to study" - while relying on the Pearson handbook's 308-item, 360-minute format for "how the exam is actually delivered." Mixing up an outdated question count with the current exam format is a common source of confusion, and it's worth double-checking scheduling and format details against TX-MP Exam Dates 2026: Testing Windows, Deadlines & Scheduling before you finalize your prep timeline.

Fees, Eligibility, and Scheduling Basics

Domain content is only half the picture - you also need to understand the mechanics of getting to test day. Ordinary eligibility for the Texas Master Plumber License Exam requires a current qualifying journeyman license held for at least two years, or one year when paired with a qualifying U.S. Department of Labor-approved apprenticeship. An equivalent out-of-state Master pathway also exists for candidates coming from another jurisdiction. Board approval and fingerprint requirements apply as part of the process, and candidates should use the January 2026 examination application for current eligibility and application procedures.

On the cost side, the Board application processing fee is $25, plus a Pearson examination fee of $128.50, for a combined total of $153.50 to sit for the exam. If you pass, the initial Master license fee is $75. For anyone budgeting the full path to licensure - including renewal costs down the road - the TX-MP Certification Cost 2026: Complete Pricing Breakdown article lays out every fee in one place.

Pearson permits up to five attempts within a one-year eligibility window, but Board-imposed waiting periods apply between attempts: 30 days after a first failure, 60 days after a second, and 90 days after any subsequent failure. That waiting-period structure is a strong argument for treating your first attempt seriously rather than planning to "retake and learn." A detailed eligibility walkthrough is available in TX-MP Requirements 2026: Eligibility, Prerequisites & How to Qualify, and if you want a plain answer on what 70% actually means in scoring terms, see TX-MP Passing Score 2026: Exactly What You Need to Pass.

Mapping a Study Plan to the 12 Domains

Rather than studying domains in numerical order, it makes sense to sequence them by dependency. Math (Domain 6) supports the sizing-chart domains (8-11), which in turn feed directly into the Domain 12 design problem. Codes, safety, accessibility, LP-gas, and license law (Domains 1, 2, 3, 4, 5, 7) can be studied in parallel since they're largely independent of one another.

This sequencing avoids the common mistake of leaving the sizing-chart and design domains for the final days, when there's little time left to build the speed those tasks require. For a condensed, one-page reference you can revisit during this final stretch, see the TX-MP Cheat Sheet 2026: One-Page Review of Must-Know Facts. And when you're ready to test your recall under timed conditions across all 12 domains, practicing on our full-length practice tests is one of the most direct ways to see where you stand before test day.

Frequently Asked Questions