- CO-MP is the Colorado Master Plumber License Exam, regulated by the Colorado State Plumbing Board (DORA) and delivered via PSI Services LLC.
- The exam has 120 scored multiple-choice questions in 270 minutes, plus up to 10 unscored items with 30 extra minutes.
- The June 18, 2026 PSI bulletin lists a passing score of 70% (84 out of 120 questions).
- Master licensure requires 8,500 verified practical-experience hours that someone other than the applicant must confirm.
What Is CO-MP Certification?
CO-MP stands for the Colorado Master Plumber License Exam - the credentialing exam that plumbing professionals in Colorado must pass to qualify for Master Plumber licensure. It is not a private industry certification; it's a state-regulated licensing exam administered under the authority of the Colorado State Plumbing Board, a division of the Department of Regulatory Agencies (DORA). If you've searched other pages on this topic, you may have also seen our companion pieces What Is CO-MP?, CO-MP Meaning, and What Does CO-MP Stand For? - all of which confirm the same identity: this acronym, on this site, refers exclusively to the Colorado Master Plumber License Exam.
Passing the CO-MP exam demonstrates that a candidate has the technical knowledge to design, install, and oversee plumbing systems at the highest level of licensure in Colorado. It is a computer-based, multiple-choice exam covering everything from water supply sizing to fire sprinkler basics, and it's a required step - though not the only step - toward earning a Master Plumber license.
Who Administers the Exam
The Colorado State Plumbing Board sets the licensing rules and standards under Colorado regulations (see 3 CCR 720-1.4), while PSI Services LLC handles exam delivery, scheduling, and scoring. This split is typical of state licensing structures: the board defines what's tested and the passing standard, and the testing vendor runs the logistics - computer-based testing centers, exam bulletins, and score reporting.
Anyone studying for this exam should treat the PSI candidate bulletin as the primary source of truth, since it's updated periodically (for example, the June 18, 2026 bulletin) and can change details like the reference code edition or scoring method between updates. If you want a broader look at who is hired based on this credential and how it fits into a plumbing career, our CO-MP Jobs and CO-MP Training pages cover that context in more depth.
Exam Format and Scoring
The CO-MP exam is a computer-based, multiple-choice test. Candidates answer 120 scored questions within 270 minutes. In addition, the exam may include up to 10 unscored pretest questions, for which candidates receive an additional 30 minutes. These unscored items are indistinguishable from scored ones during the test, so every question should be treated as if it counts.
According to the June 18, 2026 PSI bulletin, the passing score is 70%, which translates to 84 correct answers out of 120 scored questions. This is based on overall performance across the exam rather than a minimum score in each individual domain - meaning a candidate can be relatively weaker in one area as long as overall performance clears the threshold. That said, since some domains carry far more questions than others, ignoring a heavily weighted domain is riskier than ignoring a lightly weighted one.
Key Takeaway
Because scoring is based on overall performance, prioritize study time on the highest-weighted domains - Sanitary Drainage Systems and Vents - rather than spreading effort evenly across all 11 areas.
For a full breakdown of exactly how the passing threshold works and what it means in practice, see CO-MP Passing Score 2026: Exactly What You Need to Pass.
The 11 Exam Domains
The CO-MP exam blueprint is organized into 11 domains, each with a fixed number of scored questions. Understanding this distribution is essential for planning study time efficiently - it's the single most CO-MP-specific piece of information a candidate can use.
| Domain | Scored Questions |
|---|---|
| 1. Water Supply | 16 |
| 2. Vents | 20 |
| 3. Fixtures and Equipment | 10 |
| 4. General Regulations | 6 |
| 5. Traps, Interceptors, and Separators | 6 |
| 6. Storm Drainage Systems | 12 |
| 7. Sanitary Drainage Systems | 22 |
| 8. Indirect and Special Waste Piping | 6 |
| 9. Isometric Analysis | 10 |
| 10. Residential Fire Sprinklers | 4 |
| 11. Water Heaters | 8 |
Sanitary Drainage Systems is the largest domain at 22 questions, followed by Vents at 20. Together these two domains account for a substantial share of the total 120 scored questions, which makes them the highest-leverage topics to master.
Domain 7: Sanitary Drainage Systems
As the largest domain on the exam, this area covers pipe sizing, slope, cleanout placement, and drainage fixture unit calculations. Candidates should be comfortable moving between code tables and real-world layout scenarios.
- Practice fixture unit load calculations under time pressure
- Review minimum slope and sizing tables from the 2021 IPC
Domain 2: Vents
Vent sizing, venting methods (individual, common, wet, circuit), and distance-to-trap requirements are frequent question topics. This domain rewards careful reading of diagrams and isometric layouts.
- Study allowable vent configurations for island fixtures and basements
- Practice identifying vent sizing errors in sample drawings
For a domain-by-domain walkthrough with study strategies for each of the 11 areas, see our detailed CO-MP Exam Domains 2026: Complete Guide to All 11 Content Areas.
Registration, Fees, and Scheduling
The initial exam attempt costs $78. If a retake is necessary, the retake fee is $73. Payment remains valid for one year, so candidates who register but need to reschedule within that window don't have to pay again immediately - though it's worth double-checking current terms directly with PSI when you schedule, since bulletins are updated periodically.
Testing is available in both English and Spanish. Candidates who qualify for ESL accommodations can request time-and-a-half testing time and use an approved translation dictionary during the exam. These accommodations must be arranged in advance through the standard accommodation request process, not on exam day.
A full cost breakdown, including how fees compare across initial attempts and retakes, is available in CO-MP Certification Cost 2026: Complete Pricing Breakdown. If you're mapping out testing windows and deadlines, check CO-MP Exam Dates 2026: Testing Windows, Deadlines & Scheduling for scheduling specifics.
Reference Materials and Code Books
The CO-MP exam uses an open-book-style reference system, but it's tightly controlled. PSI supplies the 2021 IPC and 2021 IRC directly at the testing center - candidates are not permitted to bring their own copies. These supplied books cannot be written in, highlighted, underlined, or indexed with tabs or sticky notes ahead of time.
Personal reference books, notes, and formula sheets are strictly prohibited. However, an on-screen calculator is provided within the testing software, so candidates don't need to bring or memorize a separate calculator tool. It's also important to note that Colorado-specific amendments to the IPC/IRC are not tested on this exam - questions are based on the base code language supplied by PSI, not local amendment layers.
Key Takeaway
Practice navigating an unmarked 2021 IPC/IRC before exam day. Since you can't tab or highlight the supplied books, speed in locating tables and sections by memory of the table of contents is a real advantage.
Experience Requirement and Licensure Path
Passing the CO-MP exam is a necessary step, but it is not the same as qualifying for a Master Plumber license. Colorado requires 8,500 verified practical-experience hours for Master licensure, and candidates cannot verify their own experience - someone else, typically a supervising licensed plumber or employer, must confirm those hours through the official process.
Importantly, candidates are expected to take the examination before applying for the license, but passing the exam does not by itself establish experience eligibility. These are two separate tracks that both have to be satisfied: the knowledge test (CO-MP exam) and the documented, third-party-verified experience hours.
For a complete rundown of eligibility rules, prerequisite documentation, and how the experience-hour verification process works, see CO-MP Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Renewal and Continuing Education
Once licensed, Master Plumbers in Colorado must complete continuing education to keep their license active. The current requirement is eight CE hours each year, totaling 16 hours across the March 1, 2025-February 28, 2027 cycle. First-time licensees who just passed the exam and obtained licensure are exempt from CE requirements until their first renewal - so a newly licensed plumber doesn't need to scramble for CE hours in their very first partial cycle.
Looking ahead, three-year renewal terms begin March 1, 2027, which will change the CE accounting period going forward. Candidates currently studying for the CO-MP exam should keep this renewal structure in mind, since license maintenance is an ongoing commitment that starts the moment the license is issued.
Preparing for the CO-MP Exam
Because the CO-MP exam blends code-lookup skills with applied plumbing knowledge, effective preparation isn't just about memorizing numbers - it's about practicing efficient navigation of the 2021 IPC and IRC under time pressure, combined with solid conceptual understanding of drainage, venting, and water supply systems.
A reasonable way to structure preparation is to allocate more review time to domains with more scored questions. For example, spend early study weeks on Sanitary Drainage Systems and Vents - the two largest domains - before moving to mid-weight areas like Water Supply, Storm Drainage Systems, Fixtures and Equipment, and Isometric Analysis, and finishing with the smaller domains like General Regulations, Traps/Interceptors/Separators, Indirect and Special Waste Piping, Water Heaters, and Residential Fire Sprinklers.
Sanitary Drainage Systems & Vents
- Drill fixture unit calculations and pipe sizing tables
- Practice vent configuration diagrams and isometric reading
Water Supply, Storm Drainage & Isometric Analysis
- Review supply pipe sizing and fixture demand
- Practice reading full isometric drawings for code compliance
Remaining Domains & Full-Length Practice
- Cover Fixtures, Traps/Interceptors, Water Heaters, and smaller domains
- Run timed practice sessions using an unmarked code book
For a more detailed week-by-week plan and first-attempt strategy, see CO-MP Study Guide 2026: How to Pass on Your First Attempt. If you want a condensed, one-page reference of must-know facts to review right before your exam date, our CO-MP Cheat Sheet 2026: One-Page Review of Must-Know Facts is built for that purpose. You can also build timed familiarity with the question style using practice exams on our main practice test platform before test day.
Many candidates also want to know how the CO-MP exam compares in difficulty to other trade licensing tests, and whether the investment pays off over a career. Those questions are covered in How Hard Is the CO-MP Exam? Complete Difficulty Guide 2026 and Is the CO-MP Certification Worth It? Complete ROI Analysis 2026, while broader career and pay context appears in CO-MP Salary Guide 2026: Complete Earnings Analysis and CO-MP Pass Rate 2026: What the Data Shows.
Frequently Asked Questions
Here, CO-MP refers exclusively to the Colorado Master Plumber License Exam, administered under the Colorado State Plumbing Board (DORA) through PSI Services LLC. It is not related to any other credential that might share the same acronym elsewhere.
The exam has 120 scored multiple-choice questions with 270 minutes to complete them. Up to 10 additional unscored questions may appear, adding 30 extra minutes to the total testing time.
The June 18, 2026 PSI bulletin specifies a passing score of 70%, equal to 84 correct answers out of the 120 scored questions, based on overall performance rather than per-domain minimums.
No. PSI supplies the 2021 IPC and IRC at the testing center, and these cannot be written in, highlighted, or tabbed in advance. Personal reference books and formula sheets are prohibited, though an on-screen calculator is provided.
No. Passing the exam is required before applying for licensure, but it does not establish experience eligibility. Master licensure separately requires 8,500 verified practical-experience hours confirmed by someone other than the applicant.