Journeyman Plumber Exam Study Guide

Quick Facts

Start with Your State’s Code

Plumbing is licensed by states and, in some places, by cities or counties. Before you study, find out three things from your licensing board or candidate bulletin:

1. Which model code the exam uses. Many states adopt the International Plumbing Code (IPC). Others use the Uniform Plumbing Code (UPC), and a few use their own code.
2. Which edition. Model codes are revised every three years, and states adopt them on their own schedules, often with amendments.
3. The exam format: how many questions, whether it is open book, and whether there is a practical or drawing section.

This guide uses the 2021 IPC. If your state uses the UPC, the topics are similar, but many numbers differ. Use your own code book to confirm every value before you rely on it.

How the IPC Is Organised

Chapters 3, 6, 7, 9 and 10 carry most exam questions. Chapter 2 matters too, because questions often hinge on a defined term such as “trap arm”, “stack vent” or “developed length”.

Chapter 3: General Regulations

Chapter 3 holds rules that apply to every system.

• Protection of pipe (305). Pipe in a bored hole or notch closer than 1½ in to the edge of a framing member must be protected with steel shield plates. Pipe must also be protected from freezing and from corrosion where it passes through concrete or masonry.
• Supports (308). Table 308.5 sets maximum spacing for hangers. For example, PVC and ABS horizontal pipe needs support every 4 ft, PEX every 32 in, and copper tubing 1¼ in and smaller every 6 ft.
• Tests (312). Drain, waste and vent (DWV) systems are tested with water to at least a 10 ft head for 15 minutes, or with air at 5 psi for 15 minutes. Water supply systems are tested with water at not less than working pressure, or, for piping other than plastic, with air at not less than 50 psi.

Chapter 4: Fixtures

Learn the fixture clearances in 405.3.1: at least 15 in from the center of a water closet to a side wall or partition, 30 in center to center between adjacent water closets, and 21 in of clear space in front. Showers need at least 900 square inches of floor area with a minimum dimension of 30 in (417.4). Shower and tub-shower valves must be pressure-balancing, thermostatic or a combination, and limited to protect users from scalding.

Chapter 5: Water Heaters

Relief valve discharge is a favourite exam topic. Under 504.6 the discharge pipe must:

• be no smaller than the valve outlet,
• discharge through an air gap,
• end no more than 6 in above the floor or waste receptor,
• flow by gravity,
• have no valves or tee fittings, and
• not have a threaded end.

Where a water heater could leak and cause damage, 504.7 requires a pan at least 1½ in deep, drained by a pipe of at least 3/4 in. Section 502.1.1 requires fuel-fired water heaters in garages to have their ignition sources at least 18 in above the floor, unless the appliance is listed as flammable-vapor ignition resistant.

Chapter 6: Water Supply

Key rules:

• The minimum water service size is 3/4 in (603.1).
• Water service and building sewer piping need 5 ft of horizontal separation, unless an exception in 603.2 applies.
• Where static pressure exceeds 80 psi, install a pressure-reducing valve (604.8).
• Quick-closing valves need water hammer arrestors (604.9).
• Pipe and fittings for drinking water must not exceed a weighted average of 0.25% lead (605.2).
• Where a check valve or backflow preventer makes the system closed, storage water heaters need thermal expansion control (607.3.2).
• Section 608 covers backflow protection. An air gap must be at least twice the diameter of the effective opening, with minimums in Table 608.15.1.

Chapter 7: Sanitary Drainage

This is where most calculation questions come from. Learn the minimum slopes in Table 704.1:

Know the fixture unit values in Table 709.1 for common fixtures, the drain sizing tables in 710.1, the fitting rules in Table 706.3 and the cleanout rules in 708. Our DWV Sizing and Venting for the Plumbing Exam works through these with examples.

Chapter 9: Vents

Vents protect trap seals by keeping drainage pressure near atmospheric. Learn the trap-to-vent distance table, the minimum vent sizes, and the rules for vent terminals, such as the 3 ft and 10 ft rule for vents near windows and doors in 903.5. Air admittance valves (918) are allowed in some cases, but they cannot be the only vent for a building drain.

Chapter 10: Traps and Interceptors

Each fixture needs a trap with a liquid seal of 2 to 4 in (1002.4). Fixtures must not be double trapped (1002.1). Prohibited traps include S-traps, bell traps, crown-vented traps and traps with moving parts (1002.3). Grease interceptors are required where food service discharges fats, oils and grease (1003.3.1).

Worked Examples

These original examples show how exam questions combine a rule with simple arithmetic.

Slope. A 4 in building drain runs 60 ft from the house to the property line. What is the minimum fall? Pipe from 3 to 6 in needs 1/8 in per foot, so 60 × 1/8 = 7.5 in.

Pressure. The street main delivers water at a static pressure of 95 psi. What does the code require? Static pressure above 80 psi requires a pressure-reducing valve under 604.8. If that valve or a backflow preventer makes the system closed, the water heater also needs thermal expansion control.

Hydraulics. How much pressure is lost lifting water to a fixture 30 ft above the meter? Each foot of elevation costs about 0.433 psi, so 30 × 0.433 ≈ 13 psi. That loss is subtracted from the available pressure when sizing the water distribution system.

Fixture units. A branch serves two lavatories and a kitchen sink. Using Table 709.1, the total is 1 + 1 + 2 = 4 DFU, which a 2 in horizontal branch can carry, since 2 in is rated for 6 DFU.

Clearance. A designer places a water closet 13 in from the side wall to its centerline. Is that allowed? No. Section 405.3.1 requires at least 15 in.

A Four-Week Study Plan

• Week 1: Read the definitions in Chapter 2 and skim Chapters 3 and 4. Learn the chapter layout so you can open the book to the right chapter in seconds.
• Week 2: Chapters 5 and 6. Make flash cards for pressures, sizes and relief valve rules.
• Week 3: Chapters 7 and 10. Practise fixture unit totals, drain sizing and slope arithmetic every day.
• Week 4: Chapter 9 and full timed practice. Review every missed question in the code book.

Take our Journeyman Plumber Practice Test (IPC 2021) during weeks 3 and 4. It draws from a pool of original questions, each with an IPC reference.

Common Mistakes

• Mixing up codes. UPC values for fixture units and trap arms differ from IPC values.
• Using the wrong slope. A 3 in pipe needs 1/8 in per foot under the IPC, not 1/4 in.
• Forgetting the relief valve rules. No valves, no threads at the end, and no more than 6 in above the floor or receptor.
• Using sanitary tees in the wrong direction. They are allowed only for horizontal-to-vertical changes in drainage.
• Ignoring local amendments. Your jurisdiction may change any section of the model code.

On Exam Day

Bring the identification and materials your bulletin lists, and nothing else. Read each question twice: plumbing questions often depend on a single word, such as “horizontal” or “vertical”, “minimum” or “maximum”. Answer the quick lookups first and come back for the calculations.

Where to Go Next

• EPA 608 Apprentice Exemption