- What "MD-MP" Actually Stands For
- Who Administers the Exam
- Exam Format and Question Style
- The 10 Domains Behind the Acronym
- Eligibility, Fees, and Application Mechanics
- What You Can Bring Into the Room
- After You Pass: License, Renewal, Insurance
- Who Hires Maryland Master Plumbers
- Scheduling Your Prep Around the Domain Weights
- FAQ
- MD-MP refers to the Maryland Master Plumber License Exam, administered through the Maryland State Board of Plumbing with PSI Examination Services.
- The exam is 100 scored multiple-choice questions in 240 minutes, with a 70% passing score.
- Gas Appliances and Piping carries 40 of the 100 scored questions - by far the largest domain.
- Eligibility requires two years as a journey plumber plus 3,750 supervised training hours.
What "MD-MP" Actually Stands For
On this site, MD-MP means one thing only: the Maryland Master Plumber License Exam. Other industries use similar-looking abbreviations for entirely different credentials, but none of that applies here. If you found this page while researching a career move in the plumbing trade in Maryland, you're in the right place - MD-MP is the licensing exam that separates a journeyman plumber from a Master Plumber under the Maryland Department of Labor.
Specifically, the selected examination most candidates sit for is the combined Master Plumber/Gas Fitter exam. Passing it is the gateway to independently pulling permits, running a plumbing business, and taking on the legal responsibility that comes with the master designation. If you want a broader introduction before diving into logistics, our companion piece on What Is MD-MP? covers the big picture, and MD-MP Meaning digs into the terminology in more depth.
Who Administers the Exam
The Maryland State Board of Plumbing, housed within the Maryland Department of Labor, sets the licensing requirements and content outline. Actual exam delivery - scheduling, seat assignment, scoring - runs through PSI Examination Services, a third-party testing vendor used across many state licensing boards. That split matters practically: eligibility documentation and license issuance flow through the Board, while exam-day logistics, identification checks, and reference-material rules come from PSI.
This two-party structure is common in state trades licensing, but it trips up candidates who assume one office handles everything. If a question is about "can I bring this book" or "how do I reschedule," that's a PSI matter. If it's about "am I eligible" or "how do I get my license after passing," that's the Board. Our MD-MP Requirements 2026 guide walks through exactly which office to contact for each step.
Exam Format and Question Style
The Maryland Master Plumber/Gas Fitter exam is computer-based and multiple choice. Candidates face 100 scored questions with a time allowance of 240 minutes (four hours). The passing threshold is 70% - meaning you need at least 70 of the 100 scored items correct.
One detail candidates frequently overlook: PSI may insert five to 10 unscored experimental questions into the exam. These items are used to evaluate future exam content and don't count toward your score, but critically, the time spent answering them does not come out of your four-hour scored allowance - PSI excludes that response time separately. Practically, this means your test session may feel slightly longer than "100 questions," and you shouldn't panic if a question feels oddly worded or unfamiliar; it may simply be an experimental item.
Key Takeaway
Pace yourself against 100 scored questions in 240 minutes, but don't be thrown off if the session includes a handful of extra, unscored items - they're normal and excluded from your official timing calculation.
For a deeper look at how the scoring threshold interacts with domain weighting, see MD-MP Passing Score 2026. And if you're wondering how tough the format actually is in practice, How Hard Is the MD-MP Exam? breaks down the difficulty picture using only verified figures.
The 10 Domains Behind the Acronym
Understanding what MD-MP actually tests means understanding its ten content domains and how many of the 100 scored questions come from each. Here is the official allocation:
| Domain | Questions |
|---|---|
| 1. Plumbing Fundamentals and Safety | 5 |
| 2. Materials, Uses, and Specifications | 6 |
| 3. Traps, Interceptors, and Backwater Valves | 4 |
| 4. Plumbing Fixtures, Fixture Fittings, and Plumbing Appliances | 4 |
| 5. Water Supply Systems | 8 |
| 6. Backflow Prevention | 10 |
| 7. Drain, Waste, and Vent Systems | 13 |
| 8. Special Topics | 3 |
| 9. Gas Appliances and Piping | 40 |
| 10. Plumbing Mathematics | 7 |
Domain 9: Gas Appliances and Piping
Because this domain is weighted at 40%, it deserves more study hours than any other single area combined with a second domain. Expect questions on gas pipe sizing methods, appliance connections, venting requirements, and shutoff valve placement.
- Pipe sizing tables and demand calculations
- Appliance-specific venting and clearance rules
- Shutoff valve and connector requirements
Domain 7: Drain, Waste, and Vent Systems
At 13 questions, DWV systems are the second-largest content area. Candidates should be comfortable with trap arm distances, vent sizing, and drainage fixture unit calculations.
- Fixture unit loading and pipe sizing
- Vent system configurations
- Cleanout placement rules
Domain 6: Backflow Prevention
With 10 scored questions, backflow prevention is closely tied to a documentation requirement you'll need before you can even sit for the exam - a current, approved 32-hour backflow prevention device testing certificate. Study the device types and application scenarios the certificate program covers.
- Device selection by hazard degree
- Testing and certification documentation
- Cross-connection scenarios
For a complete walkthrough of every domain with study guidance for each, read MD-MP Exam Domains 2026: Complete Guide to All 10 Content Areas.
Eligibility, Fees, and Application Mechanics
To sit for the MD-MP exam, standard eligibility requires holding a journey plumber license for at least two years and completing 3,750 supervised training hours under a licensed master plumber. This isn't a credential you can shortcut into - it presumes real field time.
The exam fee is $65 per attempt. Under the fee schedule effective July 1, 2025, an initial master license and each renewal each cost $87.50. Applications have been online-only since March 31, 2025, so paper submissions are no longer accepted. If you fail an attempt, you may retest, but no more often than every 30 days - plan your study calendar with that cooldown in mind rather than assuming you can retest the next week.
Once you pass, you must apply for the license within one year of your passing date, or you risk having to requalify. A full cost breakdown, including how these fees compare across the license lifecycle, is available in MD-MP Certification Cost 2026: Complete Pricing Breakdown. For the complete prerequisite checklist, see MD-MP Requirements 2026.
What You Can Bring Into the Room
The MD-MP exam is open book, but the rules on what qualifies as an acceptable "book" are specific. Permanent tabs, highlighting, and underlining in your reference materials are allowed. However, handwritten notes, additional loose papers, and separate study guides are prohibited - the exam room is not the place for a cheat sheet, even a legitimate study one.
A board-linked bulletin dated September 1, 2024 lists the 2018 IPC and 2018 IFGC among the approved candidate-supplied references. That said, June 2026 board minutes discuss code revisions tied to the 2024 code cycle. Because reference editions can shift, always confirm the booked examination's reference edition before purchasing books - buying the wrong code year wastes money and study time.
Key Takeaway
Tab and highlight your approved code books early so you're not fumbling for sections on exam day, but never assume last year's edition is still current - verify with PSI or the Board before you buy or borrow references.
For a condensed, one-page version of these rules and the domain weights, bookmark MD-MP Cheat Sheet 2026: One-Page Review of Must-Know Facts.
After You Pass: License, Renewal, Insurance
Passing the exam is a milestone, not the finish line. Once licensed, your Master Plumber license runs for two years from issuance. Notably, general plumbing-license renewal carries no continuing education requirement - a detail that differs from many other trades and professions.
If you intend to contract independently, you'll need to reach insured-to-contract status, which requires at minimum $300,000 in general liability coverage and $100,000 in property-damage coverage per occurrence. Build this into your business planning before you start bidding jobs.
One more geographic wrinkle: Baltimore County and the WSSC service area maintain separate licensing authorities from the statewide Board. If you plan to work in those jurisdictions, check their local requirements in addition to your state license - a statewide Master Plumber license doesn't automatically cover every local permitting authority.
Who Hires Maryland Master Plumbers
A Master Plumber license unlocks work that a journeyman credential cannot legally perform - namely, pulling permits and taking on contractual responsibility for plumbing work. In practice, this means:
- Plumbing contracting businesses that need a licensed master of record to operate legally
- Mechanical and general contractors bidding on commercial or municipal projects requiring master-level oversight
- Property management and facilities firms maintaining multi-unit residential or institutional buildings
- Independent plumbing business owners who need the license to legally operate under their own name
Because the license is tied to real supervisory and legal authority, employers value it as proof a candidate has cleared both the field-hours requirement and a rigorous exam covering gas fitting, DWV systems, and backflow prevention. For a broader look at where this credential can take your career, see MD-MP Jobs and Is the MD-MP Certification Worth It? Complete ROI Analysis 2026.
Scheduling Your Prep Around the Domain Weights
Generic study advice rarely accounts for a domain distribution as lopsided as this exam's - Gas Appliances and Piping alone outweighs six other domains combined. Rather than splitting study time evenly across ten domains, allocate hours proportional to question count.
Gas Appliances and Piping (40 questions)
- Work through pipe sizing tables repeatedly until calculations feel automatic
- Drill appliance venting and connection scenarios from the approved IFGC reference
Drain, Waste, and Vent Systems (13) and Backflow Prevention (10)
- Practice fixture unit and vent sizing problems
- Cross-reference backflow device scenarios with your 32-hour certificate coursework
Water Supply Systems (8), Plumbing Mathematics (7), and remaining smaller domains
- Round out Materials, Fundamentals and Safety, Traps and Interceptors, Fixtures, and Special Topics
- Run a full-length timed practice session to simulate the 240-minute format
This is the only generic-methodology section you'll find here, and it's tied directly to MD-MP's own weighting - not a one-size-fits-all template. For a full week-by-week plan built around every domain and the exact question counts, see MD-MP Study Guide 2026: How to Pass on Your First Attempt. You can also sharpen your timing and question style using realistic practice questions on our main practice test platform before exam day.
Frequently Asked Questions
MD-MP refers specifically to the Maryland Master Plumber License Exam, administered by the Maryland State Board of Plumbing with PSI Examination Services handling test delivery. It is unrelated to any other credential that happens to share the same abbreviation.
The exam includes 100 scored multiple-choice questions with 240 minutes to complete them. PSI may add five to 10 unscored experimental questions, but the time spent on those is excluded from your four-hour scored allowance.
Gas Appliances and Piping, which carries 40 of the 100 scored questions - by far the largest single domain. Drain, Waste, and Vent Systems (13) and Backflow Prevention (10) are the next priorities.
Retesting is allowed no more often than every 30 days. Each attempt requires paying the $65 exam fee again, so it pays to prepare thoroughly rather than rely on frequent retakes.
No. General plumbing-license renewal in Maryland has no continuing education requirement. Licenses run two years from issuance, and renewal carries an $87.50 fee under the schedule effective July 1, 2025.