Idaho Plumbing Journeyman Exam

Idaho Plumbing Journeyman Exam: What You Need to Know to Pass in 2026

You've put in the hours in the field. The Idaho Plumbing Journeyman Exam is one of the steps between you and the license. It's not a test of how fast you can sweat a joint — it's a test of whether you can find a rule in the code book and apply it to a real job. Get comfortable with the books and the format, and this exam is very manageable.

This guide walks through what's on the Idaho Plumbing Exam, what the questions look like, what to study, and how to pace yourself on test day.

Idaho Plumbing Journeyman Exam Overview

The Idaho Plumbing Journeyman Exam is administered by PSI. It is an open book exam — but that cuts both ways. Open book does not mean easy. You still have to know your way around the code books well enough to land on the right section, number, or exception quickly. If you don't know roughly where a rule lives before you open the cover, you'll burn time you don't have.

Here are the details that matter before you sit down:

On exam day

• You must present one current, government-issued photo and signature ID (such as a driver's license, state ID card, passport, military ID, or alien registration card) to be admitted.
• Arrive 15 minutes before your appointment time.
• Candidates must bring their own approved references, may not write in them during the exam, and may not have additional papers or temporary markers, which will be confiscated.
• Pre-exam highlighting, underlining, and permanent indexing are permitted, but temporary markers such as Post-its are prohibited and no writing is allowed during the exam.
• Only approved items may be brought into the exam room; all other personal belongings, including electronics, writing devices, bags, food and drinks, must be placed in secure storage.

References you may bring

• Uniform Plumbing Code (UPC), ISBN-13: 9781938936647 (2015)
• Idaho State Plumbing Code (2017 ISPC), ISBN-13: 9781938936951

Scheduling, changes and retakes

• You may schedule online through PSI's registration website or by calling PSI at 855-340-3713.
• You may cancel and reschedule without forfeiting your fee if PSI receives your cancellation notice 2 days before the scheduled examination date, done by website or by phone (not voicemail or email).
• If you miss your appointment, arrive after the examination start time, cancel late, or lack proper ID, your registration is invalid and you forfeit your examination fee.
• Your score is shown on screen at the end of the exam and a score report is provided, with a diagnostic report of strengths and weaknesses if you fail.
• If you do not pass, you may retake the exam as many times as needed, paying an examination fee for each attempt.

Source: Examination Scheduling Procedures / Examination Guide (Idaho PSI Candidate Bulletin), Effective 7/9/2026. Check the bulletin before test day: fees and rules can change.

Topics Covered on the Idaho Plumbing Exam

The exam is built on the 2015 Uniform Plumbing Code and the 2017 Idaho State Plumbing Code. Here's how the items break down, heaviest first.

2017 Idaho State Plumbing — 25 items (25%)
A full quarter of the exam. This covers Idaho's amendments: testing and inspection under the amended Section 105.3, the definition of "plumbing system" pulled from Idaho Code, shower receptor floor slope, the Category 3/4 vent air test, the 18-inch ignition-source height in residential garages, frost-proof hose bibbs, tracer wire exceptions, yard piping cover, the two-fixture-unit values for bathtubs and clothes washers, the pre-plumbed softener loop in new residences, double sanitary tees, cleanout locations and spacing, ejector and sump exceptions, and the 4-inch building sewer. Air admittance valve rules show up here too — where they're allowed and where they aren't. Our practice questions in this group ask things like the minimum slope of a shower receptor floor toward the drain and the minimum diameter of drainage or vent piping run underground or below a basement.

2015 UPC Chapter 12 — Fuel Gas Piping — 12 items (12%)
Sizing and allowable pressure drop, approved metallic and plastic materials, joining methods, underground and aboveground installation, pressure testing and purging, inspection authority, meters and regulators, appliance connections and sediment traps, and bonding and grounding. Questions here hit minimum cover for underground piping, tracer wire size for plastic pipe, prohibited metallic materials, brazing melting points, the maximum pressure the chapter governs, and what happens when an existing system is undersized for a new appliance.

2015 UPC Chapter 11 — Storm Drainage — 10 items (10%)
Approved materials, sizing roof drains, conductors, leaders and horizontal storm drains from the tables, primary and secondary roof drainage, subsoil drains and sumps, controlled-flow systems, traps on leaders connected to combined sewers, and water and air testing. Expect questions on minimum subsoil drain pipe diameter, minimum sump pump capacity, which sewer storm water may never enter, and where a subsoil drain may discharge.

2015 UPC Chapter 7 — Sanitary Drainage — 9 items (9%)
Drainage materials by location above and belowground, DFU values and pipe sizing, joints, cleanout location and spacing, grade and slope, fixtures below the sewer level, building sewers, and approved fittings for changes in direction. Our practice questions cover the minimum slope for horizontal drainage piping, backwater valve requirements, the restriction on galvanized steel underground, and sumps and ejectors for fixtures below the crown level of the main sewer.

2015 UPC Chapter 9 — Vents — 9 items (9%)
Vent sizing by fixture units and developed length, terminations and clearances, grades and connections, wet venting, circuit venting, island fixture venting, combination waste and vent limits, and vent stacks. Questions ask for minimum individual vent diameter, vent terminal size where frost closure is likely, the maximum pressure differential a vent system must prevent at a trap seal, island sink vent requirements, and the branch length limit in a combination waste and vent system.

2015 UPC Chapter 4 — Plumbing Fixtures — 8 items (8%)
Fixture clearances and securing, required fixture counts by occupancy from Table 422.1, flow rates and consumption limits, shower compartment construction, fixture-specific standards, flushing devices, hot water temperature limits, and prohibited fixtures. Expect clear-space dimensions in front of a water closet, showerhead flow rate, water closet consumption per flush, and the single-unisex-facility exceptions for small occupant loads.

2015 UPC Chapter 6 — Water Supply — 8 items (8%)
Backflow devices and assemblies, cross-connection control, approved materials and lead content, joining methods by material, pressure regulation and expansion tanks, sizing from Table 610.4, identification of potable and nonpotable piping, and residential fire sprinkler systems. Questions cover the color scheme for potable water identification, marking intervals for nonpotable systems, lead content limits in solder and flux, the restriction on PEX near a water heater, and clearance under a backflow assembly.

2015 UPC Chapter 3 — General Regulations — 6 items (6%)
Material standards and markings, prohibited fittings, protection of piping through structural members, hangers and support intervals, trenching and backfill, alternate materials, flood hazard areas, and test gauge ranges. Our practice questions ask about UV protection for PVC exposed to sunlight, where dissimilar metal connections must be made, soil pipe over food preparation areas, and clear height in tunnels between open-cut trenches.

2015 UPC Chapter 10 — Traps and Interceptors — 5 items (5%)
Trap installation, trap arm lengths from Table 1002.2, prohibited traps and seal depths, grease interceptor types and sizing, sand interceptors, oil interceptors, and floor drain trap seals. Questions hit food waste disposer trapping, maximum trap arm developed length, which trap types are prohibited, and the required liquid seal depth range.

2015 UPC Chapter 5 — Water Heaters — 4 items (4%)
Location and prohibited installations, relief valves, combustion air sizing, Category I venting, terminations, vent connectors, support and drain pans. Expect clearances for unlisted water heaters, minimum drain pan depth, and combustion air free-area and volume calculations.

2015 UPC Chapter 8 — Indirect Wastes — 4 items (4%)
Air gaps and air breaks, food and beverage establishments, receptors, condensate disposal and overflow protection, chemical waste, condensers and sumps, pressure drainage and softener discharge, and clear water wastes. Questions cover water softener drain terminations, trapping and venting of indirect waste pipes by length, condensate overflow protection, and minimum drainage air gap.

Sample Practice Questions

Here are four practice questions from our question bank. Answers aren't shown — work them with your code book, then test yourself on more questions in the free practice exam.

1. As a journeyman plumber, you are installing floor drains in a warehouse that will only be used occasionally for cleaning. The drains connect directly to the drainage system. A co-worker suggests that since the drains will rarely be used, no additional protection is needed. According to the 2017 ISPC, what is required?

A. No additional protection is required since floor drains are self-sealing
B. A backwater valve must be installed on each floor drain
C. A trap seal primer or other approved trap seal protection device must be installed
D. The floor drains must be capped when not in use

Tests the 2017 ISPC requirement for floor drains connected to the drainage system.

2. You are called to a job site where a contractor has installed underground plastic gas piping and has already backfilled the trench. The inspector has not yet approved the installation. According to the 2017 ISPC, what is required?

A. The installation is acceptable as long as the contractor provides photos of the piping before backfill
B. A pressure test can be performed through the backfill without exposing the piping
C. The piping must be exposed upon direction of the Authority Having Jurisdiction
D. A new permit must be obtained and the entire installation must be replaced

Tests inspection requirements for concealed underground gas piping.

3. You are called to a residential job site where groundwater is continuously flowing into a basement sump. The homeowner wants you to discharge the sump pump onto a splash block in the yard. According to the 2017 ISPC, what should you advise the homeowner?

A. This is acceptable as long as the splash block is at least 24 inches long
B. This is not permitted because continuously flowing groundwater must be piped to a storm drain or approved water course
C. This is acceptable as long as the discharge point is 10 feet from the property line
D. This is not permitted because all sump pumps must discharge to a sanitary sewer

Tests subsoil drain discharge rules for continuously flowing groundwater.

4. You are a journeyman plumber connecting a horizontal drainage line to a vertical stack. The building inspector asks you about the approved fittings for this connection. Which of the following fittings would NOT be an approved method for connecting a horizontal drainage line to a vertical stack?

A. 45-degree wye branch
B. Combination wye and one-eighth bend
C. Sanitary tee branch
D. Short-sweep 90-degree elbow

Tests approved fittings for changes in direction of drainage flow.

What Types of Questions to Expect

The practice questions in this guide fall into three shapes.

Straight lookups. A number or a rule: minimum slope, minimum diameter, maximum flow rate, required clearance. These are the fastest points on the exam if you know which chapter to open.

Job-site scenarios. You're handed a situation — a homeowner wants something, a contractor already did something wrong, an architect drew something questionable — and you pick the code-correct answer. The rule is still a lookup; the wrapper just makes you decide which rule applies.

Negative items. "Which would NOT be approved." Read these twice. A rushed reader picks the correct-sounding option instead of the exception the question is actually asking about.

Table work shows up too — trap arm lengths, storm drain sizing, fixture units, gas pipe sizing. Practice reading the tables under time pressure, not just knowing they exist.

Study Materials for the Idaho Plumbing License Exam

Two code books anchor your study.

• 2017 Idaho State Plumbing Code (2017 ISPC) — required. Idaho's amendments are the single heaviest topic on the exam. This is the book you should know best.
• 2015 Uniform Plumbing Code (UPC) — required. The base code behind Chapters 3 through 12.
• Sharpie Highlighters — a 12-pack in assorted colors with a chisel tip. Color-code your chapters so your eye lands on the right page fast.
• Redi-Tag Permanent White Tabs — printable white index tabs, 375 per pack. Build a permanent index down the edge of each book by chapter and by the tables you'll actually use.

Also read the official bulletin start to finish, check requirements at the licensing agency website, and register through PSI.

Study Tips for the Idaho Plumbing Journeyman Exam

Weight your study time to the weight of the topics. Idaho amendments and gas piping together account for a big share of the exam. Storm drainage, sanitary drainage, and venting come next. Water heaters, indirect wastes, and general regulations are smaller. Don't spend a week on a 4% chapter while the 25% chapter sits untouched.

Build the books before you build the knowledge. Tab and highlight early, then study out of the tabbed books. Every lookup you do while studying trains your hands to find that section again. By exam day you want muscle memory, not a search party.

Learn the exceptions. Idaho's amendments change or delete specific UPC sections. Where Idaho changed a rule, answer with the Idaho version, not the unamended UPC one. Know which sections Idaho amended and which it deleted outright.

Work tables out loud. Pick a fixture group, size the drain, size the vent, size the gas run. Do it until the columns stop looking like a wall of numbers.

Pace yourself. You have about 1 minute 48 seconds per question. Straight lookups should go faster than that. That surplus is what pays for the table problems that eat real time. If a question stalls you, move on. Never let one item eat the budget for five others.

Open book is a tool, not a safety net. Answer from memory when you're sure, verify only when you're not, and look up every number you'd be guessing at. Reading whole sections during the exam is how people run out of time.

Do timed Idaho plumbing journeyman exam practice. Sitting down and grinding through 100 questions under the clock, with your tabbed books, is the closest thing to the real experience. It shows you which chapters you can find blindfolded and which ones cost you a minute every time.

One last note: if you're wondering How much do journeyman plumbers make in Idaho? — check current wage data from the state and from employers in your area. The license is what puts you in position to ask for it.

Ready to Test Your Knowledge?

Start with 10 questions on the house, then run 100 questions against the clock when you're ready to see where you stand. Every question comes with an explanation and a code citation so you can go straight to the section in your book.

Grab your code books, start the clock, and take the free practice exam.