- CO-JP refers to the Colorado Journeyworker Plumber exam, administered by PSI Services LLC for the Colorado State Plumbing Board.
- The exam has 100 scored questions in 240 minutes, plus up to 10 unscored pretest items in a separate 30-minute window.
- Passing requires 70 correct scored answers out of 100 - a 70% score.
- It's open-book using only PSI-supplied 2021 IPC and 2021 IRC copies; Colorado amendments are not tested.
What Is a CO-JP?
"CO-JP" is a shorthand identifier used across this site for the Colorado Journeyman Plumber License Exam - officially the exam that leads to the Journeyworker Plumber (JP) license designation issued by the Colorado State Plumbing Board. If you've searched "what is CO-JP" or landed here wondering whether this is the same acronym you've seen attached to some other industry credential, it isn't. On this site, CO-JP means one thing only: the computer-based licensing exam that Colorado plumbers must pass before they can file for their Journeyworker Plumber license through the Division of Professions and Occupations (DORA).
This article is a plain-language answer to that identity question. For deeper dives into specific angles, see our companion pieces on what CO-JP stands for, the meaning behind the CO-JP name, and what earning the CO-JP certification actually involves.
Who Administers the Exam
Two organizations sit behind the CO-JP exam. The Colorado State Plumbing Board, operating under DORA, sets the licensing requirements and owns the standards a candidate must meet. The actual test delivery - scheduling, proctoring, scoring, and the reference bulletin - is handled by PSI Services LLC, a third-party testing vendor used by many state licensing boards.
This split matters practically. Your eligibility to sit for the exam (experience hours, documentation) is a DORA/Plumbing Board matter. Everything about the day of the test - what you bring, what materials are supplied, how long you have, and what's on the reference list - comes from PSI's exam bulletin. PSI publishes bulletin 11658 for this exam, and that bulletin is the authoritative source for reference materials and testing rules. Always confirm the version tied to your booked test date before assuming anything about what's allowed in the exam room.
Exam Format and Fees
The CO-JP exam is computer-based and open-book. Here's the structure candidates should expect:
- 100 scored questions to be completed in 240 minutes.
- Up to 10 additional unscored questions, which are field-tested for future exam versions, administered in a separate 30-minute allowance outside the main scored time.
- A passing score of 70 correct scored answers, meaning you need 70% correct on the scored portion to pass.
- An on-screen calculator is provided within the testing software. Plumbing-specific formulas are neither supplied nor permitted, so calculations must be worked from first principles using code knowledge rather than memorized formula sheets.
On fees: the initial examination fee is $78, and if you need to retest, the retest fee is $73. These are exam fees specifically - they're separate from any license application fee filed with DORA after you pass. For a full breakdown of every cost a candidate might encounter across the licensing journey, see CO-JP Certification Cost 2026: Complete Pricing Breakdown.
Key Takeaway
Passing the CO-JP exam does not, by itself, make you a licensed plumber in Colorado. You still need to submit the license application to DORA after your passing score is recorded.
Open-Book References: What You Can and Can't Use
The "open-book" label surprises some candidates into thinking they can bring their own annotated code books. That's not how it works. PSI supplies the books at the test center - specifically the 2021 International Plumbing Code (IPC) and the 2021 International Residential Code (IRC), per the exam-specific reference list in bulletin 11658. Candidates are not permitted to bring personal copies, and they cannot write, highlight, underline, or index the PSI-supplied books in any way.
Two details deserve extra attention:
- Colorado amendments are not tested. The exam is based on the unamended 2021 IPC and IRC text, not on any state-specific modifications you may encounter on the job.
- Reference editions can change between bulletin revisions. Because the bulletin has been revised (most recently effective June 18, 2026), always check the current PSI reference list tied to your scheduled test date before you buy study books, so you're studying the correct code edition.
Because the books are supplied clean, the real skill being tested is navigation speed - knowing where a topic lives in the code index and how sections cross-reference each other, rather than memorizing exact code text word for word.
The 11 Content Domains
PSI structures the 100 scored questions around a published content outline covering 11 domains. Understanding the relative weight and subject matter of each domain is one of the highest-leverage things a candidate can do before scheduling a test date. For the full breakdown of every domain with study emphasis, see CO-JP Exam Domains 2026: Complete Guide to All 11 Content Areas.
Domain 7: Sanitary Drainage Systems
This is the largest domain on the exam. Candidates should expect the deepest and most frequent questioning here, covering drainage system design, sizing, slope, and code compliance for waste removal.
- Master pipe sizing tables and drainage fixture unit calculations
- Know slope and grade requirements cold
The remaining ten domains round out the outline:
- Domain 1: Water Supply - sizing, materials, and distribution of potable water systems.
- Domain 2: Vents - venting configurations that keep drainage systems functioning and trap seals protected.
- Domain 3: Fixtures and Equipment - code requirements for the fixtures plumbers install and connect daily.
- Domain 4: General Regulations - administrative and general code provisions that apply across systems.
- Domain 5: Traps, Interceptors, and Separators - devices that protect systems and the environment from waste, grease, and other substances.
- Domain 6: Storm Drainage Systems - handling of rainwater and site drainage.
- Domain 8: Indirect and Special Waste Piping - waste that requires an air gap or special handling before entering the sanitary system.
- Domain 9: Isometric Analysis - reading and interpreting isometric plumbing drawings, a skill-based rather than pure-recall domain.
- Domain 10: Residential Fire Sprinklers - code requirements specific to residential sprinkler systems.
- Domain 11: Water Heaters - installation, venting, and safety requirements for water heating equipment.
Experience Requirements and Licensing
You can't simply register for the CO-JP exam off the street. Colorado requires four years and 6,800 hours of qualifying practical experience, supported by documentation, before a candidate is eligible to test. This experience requirement is the backbone of the entire process - it's what separates the exam from a generic knowledge quiz and ties it to real field competency.
If you're still accumulating hours or are unsure whether your current work qualifies, our dedicated guide at CO-JP Requirements 2026: Eligibility, Prerequisites & How to Qualify walks through documentation expectations in more detail. It's worth confirming your eligibility timeline well before you plan to sit for the exam, since gathering supporting records can take longer than expected.
After You Pass: License Application and Renewal
Passing the CO-JP exam is a milestone, not the finish line. Candidates must pass the examination before filing the DORA license application - the two steps are sequential, not simultaneous. Once you've passed, you submit your license application to DORA to formally become a licensed Journeyworker Plumber.
Licensing doesn't end at issuance, either. Colorado currently operates on a two-year renewal cycle, but that changes to a three-year cycle for licenses issued or renewed on or after March 1, 2027. Whichever cycle applies to your license, continuing education is mandatory: eight hours annually, including at least four code hours, with no more than two safety hours counted in each 24-month period. Budget for this ongoing requirement the same way you budgeted for exam prep - it's a recurring part of maintaining the license, not a one-time hurdle.
| Item | Detail |
|---|---|
| Initial exam fee | $78 |
| Retest fee | $73 |
| Scored questions | 100 in 240 minutes |
| Unscored questions | Up to 10 in a separate 30-minute allowance |
| Passing score | 70 correct (70%) |
| Reference materials | 2021 IPC and 2021 IRC, supplied by PSI |
| Experience prerequisite | 4 years / 6,800 hours, documented |
| Renewal cycle | 2 years (3 years for licenses issued/renewed on or after March 1, 2027) |
| Continuing education | 8 hours/year, 4+ code hours, max 2 safety hours per 24 months |
Who Actually Takes This Exam
The CO-JP exam is for tradespeople who have already worked substantial hours in plumbing and are ready to move from apprentice or trainee status into a licensed Journeyworker role in Colorado. That typically means candidates working for residential and commercial plumbing contractors, mechanical contractors, and specialty trade employers throughout the state - anyone whose work requires a licensed plumber signing off on installations under the IPC and IRC.
Because the license is a formal state credential, employers hiring for journeyworker-level plumbing positions in Colorado generally expect it. If you're mapping out what comes after licensure - job titles, employer types, or how the credential affects hiring conversations - see CO-JP Jobs and CO-JP Salary Guide 2026: Complete Earnings Analysis for a broader look at where this license fits in a plumbing career path.
How to Approach Preparation
Because the exam is open-book but time-limited, preparation is less about memorizing code text and more about building speed and confidence navigating the 2021 IPC and IRC under exam conditions. A practical approach:
Build Code Familiarity
- Work through the largest domain, Sanitary Drainage Systems, first since it carries the most scored questions
- Practice locating sections in the IPC/IRC index without annotations, since the supplied books can't be marked up
Cover Remaining Domains
- Rotate through Water Supply, Vents, Fixtures and Equipment, Traps/Interceptors/Separators, and the other domains
- Practice isometric drawing interpretation for Domain 9, since it's a distinct skill from code lookup
Simulate Exam Conditions
- Time yourself completing practice questions within a 240-minute budget across 100 items
- Practice using an on-screen calculator instead of relying on memorized formulas
For a more detailed week-by-week plan and first-attempt strategy, see CO-JP Study Guide 2026: How to Pass on Your First Attempt. If you want a candid read on difficulty before you commit to a test date, How Hard Is the CO-JP Exam? Complete Difficulty Guide 2026 and CO-JP Pass Rate 2026: What the Data Shows are worth reading alongside this article. You can also run through timed practice questions on our main practice test platform to get comfortable with the format before test day.
Whether the license is worth pursuing given the time investment in hours and continuing education is a fair question to ask before you start - our analysis at Is the CO-JP Certification Worth It? Complete ROI Analysis 2026 looks at that trade-off directly. And once you're ready to lock in a test date, CO-JP Exam Dates 2026: Testing Windows, Deadlines & Scheduling covers scheduling mechanics through PSI. You can also start practicing on our practice test platform today to see where your knowledge gaps are.
Frequently Asked Questions
No. On this site, CO-JP refers specifically to Colorado's Journeyman Plumber License Exam, administered through the Colorado State Plumbing Board and delivered by PSI Services LLC. It is a state-specific exam tied to Colorado licensure, not a national or multi-state credential.
No. The exam is open-book, but PSI supplies the 2021 IPC and 2021 IRC at the test center. Personal reference books are not allowed, and the supplied books cannot be written in, highlighted, underlined, or indexed.
No. The exam is based on the unamended 2021 International Plumbing Code and 2021 International Residential Code. State-specific amendments are not part of the tested content.
There are 100 scored questions to complete within 240 minutes, plus up to 10 unscored questions administered separately within a 30-minute allowance.
No. Passing the CO-JP exam is a required step, but you must still file a license application with DORA afterward. Passing the exam alone does not confer the Journeyworker Plumber license.