- The CO-JP is 100 scored questions in 240 minutes, plus up to 10 unscored pilot items.
- Passing requires 70 correct scored answers - a flat 70%, no domain-by-domain minimums.
- Only PSI-supplied 2021 IPC and 2021 IRC books are allowed; no personal copies, no markup.
- Initial fee is $78; a retest costs $73 if you don't clear 70 the first time.
Exam Snapshot: The Numbers You Must Know
Before you touch a single practice question, memorize the mechanics. The Colorado Journeyman Plumber License Exam (CO-JP) is administered by PSI Services LLC on behalf of the Colorado State Plumbing Board, part of the Division of Professions and Occupations (DORA). The official license title you're working toward is Journeyworker Plumber (JP); "CO-JP" is simply the shorthand used across this site and your prep materials.
Here's the core structure in one block, because these numbers show up constantly in scheduling decisions and pacing strategy:
- Format: Computer-based, open-book
- Scored questions: 100, answered in 240 minutes
- Unscored (pilot) questions: up to 10, with a separate 30-minute allowance
- Passing score: 70 correct scored answers (70%)
- Calculator: on-screen calculator provided; no plumbing formulas supplied or permitted
Notice that pilot questions don't count toward your score but do get their own time block - that separation matters when you're managing pace on test day. For a deeper breakdown of how this scoring threshold works in practice, see CO-JP Passing Score 2026: Exactly What You Need to Pass.
Registration, Fees, and Retest Mechanics
Money and paperwork trip up more candidates than the plumbing code does. The initial examination fee is $78. If you don't clear the 70-question threshold, a retest costs $73. Neither figure includes any license application fee you'll pay separately through DORA after passing.
A critical sequencing point: passing the CO-JP exam does not automatically grant you a license. You must pass the exam first, then file the license application with DORA, supported by documentation of four years and 6,800 hours of qualifying practical experience. Skipping ahead - or assuming the exam and the license are the same milestone - is a common and costly misunderstanding. The full eligibility breakdown, including how experience hours are documented, lives in CO-JP Requirements 2026: Eligibility, Prerequisites & How to Qualify.
For candidates weighing the total investment - exam fees, study materials, possible retests - the cost picture is laid out in detail at CO-JP Certification Cost 2026: Complete Pricing Breakdown. If you're still deciding whether the credential justifies the time and expense, Is the CO-JP Certification Worth It? Complete ROI Analysis 2026 walks through that decision without inventing numbers that don't exist for this exam.
Key Takeaway
Confirm your testing window and any bulletin updates before registering - PSI bulletins are revised periodically, and scheduling details can shift between now and your test date. Check CO-JP Exam Dates 2026: Testing Windows, Deadlines & Scheduling before locking in a slot.
Reference Materials: What's Allowed at PSI
This is where a lot of candidates waste money or, worse, show up unprepared for how "open-book" actually works. The exam-specific reference list - PSI bulletin 11658, revised June 18, 2026 - specifies exactly two references: the 2021 International Plumbing Code (IPC) and the 2021 International Residential Code (IRC). Colorado amendments to these codes are not tested, which surprises candidates who assume state-specific rule changes will appear on the exam.
Three rules to internalize now:
- PSI supplies the books at the test center. You do not bring your own copies.
- Writing, highlighting, underlining, or indexing the supplied books is prohibited. Tabbing your home copy for practice is fine; it won't transfer to test day.
- Always check the PSI reference list tied to your specific booked test date before buying study books - code editions referenced by testing programs can be updated, and studying the wrong edition wastes real time.
All 11 Domains at a Glance
The CO-JP content outline covers 11 domains published by PSI. Treat this list as your master checklist - every study session should map back to one of these:
Domain 1: Water Supply
Sizing, materials, and distribution principles for potable water systems.
- Pipe sizing logic and water distribution fundamentals
Domain 2: Vents
Venting configurations that protect trap seals and allow proper drainage flow.
- Vent types, sizing, and required connections
Domain 3: Fixtures and Equipment
Installation and connection requirements for plumbing fixtures.
- Fixture unit values and required clearances
Domain 4: General Regulations
Administrative and code-wide requirements that apply across systems.
- Permitting, inspection, and general code provisions
Domain 5: Traps, Interceptors, and Separators
Devices that prevent sewer gas intrusion and separate waste materials.
- Trap seal requirements and interceptor sizing
Domain 6: Storm Drainage Systems
Handling of rainwater and surface drainage separate from sanitary waste.
- Sizing of storm drainage piping and roof drains
Domain 7: Sanitary Drainage Systems
The largest domain on the exam, covering waste pipe sizing, slope, and layout.
- Drainage fixture unit calculations and pipe sizing tables
Domain 8: Indirect and Special Waste Piping
Waste systems requiring an air gap or special handling before entering the drainage system.
- Indirect waste receptor requirements
Domain 9: Isometric Analysis
Reading and interpreting isometric drawings of plumbing systems.
- Tracing pipe runs and identifying code violations on a diagram
Domain 10: Residential Fire Sprinklers
Requirements specific to residential fire suppression piping.
- Coordination between sprinkler and domestic water systems
Domain 11: Water Heaters
Installation, venting, and safety requirements for water heating equipment.
- Relief valve, venting, and clearance requirements
For a full narrative walkthrough of each area with study strategies specific to that content, see CO-JP Exam Domains 2026: Complete Guide to All 11 Content Areas.
Heavy-Hitter Domains to Prioritize
Not all 11 domains carry equal weight. Sanitary Drainage Systems is the largest domain on the published outline, which means it deserves the largest single block of your study time. If you're rationing hours before test day, don't split them evenly across all 11 areas - start with drainage fixture units, pipe sizing tables, and slope requirements from Domain 7, then work outward.
Isometric Analysis (Domain 9) deserves a special note: it's less about memorizing a table and more about a skill - reading a drawing under time pressure and catching what's wrong or missing. That skill only improves with repeated practice on isometric-style questions, not passive code reading.
| Study Focus | Why It Matters |
|---|---|
| Domain 7 - Sanitary Drainage Systems | Largest domain; heaviest concentration of questions |
| Domain 9 - Isometric Analysis | Skill-based; requires practice with diagrams, not just reading |
| Domain 1 - Water Supply | Foundational sizing logic reused in other domains |
| Domain 11 - Water Heaters | Discrete, well-defined rules that are easy points if studied directly |
If you're still gauging how tough this exam is relative to the time you've set aside, How Hard Is the CO-JP Exam? Complete Difficulty Guide 2026 covers that in more depth, and CO-JP Pass Rate 2026: What the Data Shows looks at what's actually known about outcomes.
From Passing to Licensure
Passing the CO-JP exam is a gate, not the finish line. Colorado requires four years and 6,800 hours of qualifying practical experience, documented and submitted with your DORA license application. The exam confirms you know the code; the application confirms you've actually done the work in the field.
If you're new to the credential entirely and want the full picture - what the designation means, who oversees it, and how it fits into a plumbing career - start with What Is CO-JP? or CO-JP Meaning. For a broader overview of the certification itself, CO-JP Certification and What Is CO-JP Certification? cover the fundamentals in plain language.
Continuing Education and Renewal Changes
Once licensed, the work of staying current doesn't stop. Colorado requires eight hours of continuing education annually, including at least four code hours, with no more than two safety hours counted in each 24-month period. Track this carefully - the code-hour minimum and safety-hour cap are separate rules, and missing either can create renewal headaches.
There's also a structural change on the horizon: the renewal cycle is moving from two years to three years for licenses issued or renewed on or after March 1, 2027. If your renewal falls near that date, confirm which cycle applies to you directly with DORA rather than assuming.
Key Takeaway
CE requirements apply after licensure, not before the exam - but knowing them now helps you plan the full arc of maintaining your credential, not just passing the test.
Final-Week Review Schedule
A generic study calendar won't help you here - your final stretch should be built around the CO-JP's actual weight distribution and open-book format. Use this as a template, not a rigid rulebook:
Heavy Domains First
- Deep review of Sanitary Drainage Systems (Domain 7) pipe sizing and slope tables
- Cross-reference the same tables in your PSI-listed 2021 IPC/IRC editions
Skill-Based Domains
- Timed isometric drawing practice (Domain 9)
- Water Supply (Domain 1) sizing drills
Discrete Rule Sets
- Water Heaters (Domain 11), Traps/Interceptors/Separators (Domain 5), Indirect Waste (Domain 8)
- Practice locating answers quickly in the code book - speed matters under 240-minute limits
Full Simulation
- Full-length 100-question timed practice run
- Review General Regulations and Residential Fire Sprinklers as final polish
For a more detailed, structured approach to first-attempt success, see CO-JP Study Guide 2026: How to Pass on Your First Attempt. And when you're ready to test your recall under realistic conditions, our practice test platform mirrors the domain distribution and open-book pacing you'll face on exam day.
Frequently Asked Questions
The exam has 100 scored questions with a 240-minute time limit, plus up to 10 unscored questions administered with a separate 30-minute allowance.
You need 70 correct scored answers out of 100, which equals a 70% passing score. There is no separate minimum required per domain.
No. PSI supplies the 2021 International Plumbing Code and 2021 International Residential Code at the test center. Personal copies, and any markup like highlighting or tabbing, are not permitted.
No. You must pass the exam first, then file a separate license application with DORA that documents four years and 6,800 hours of qualifying practical experience.
You can retest for a fee of $73, compared to the $78 initial examination fee. Review the reference list and outline again before rescheduling.
Whether you're just starting to explore what this credential involves or you're in the final countdown to test day, keeping this one-page reference nearby - alongside resources like CO-JP Training and CO-JP Jobs for career context - helps keep the mechanics of the CO-JP exam straight while you focus your actual study time on the code itself.