Red Seal Plumber Exam: How It’s Structured and What to Focus On

Plumbing is one of the most widely written Red Seal exams. The exam tests the full national scope — not just the type of plumbing you do every day. The Steamfitter trade shares many piping fundamentals — see our Red Seal Steamfitter exam breakdown. For US plumbers, see our guide to the US Plumber Journeyman licensing exam.

The Exam Format

[VERIFY] The Red Seal Plumber exam (306A) has 125 multiple-choice questions. 4 hours. Pass mark is 70%. Content is set interprovincially based on the RSOS. For booking details, see our province-by-province guide.

The NOA Breakdown

A — Common Occupational Skills: ~19 questions (15%). Safety, trade math (offsets using 1.414 and 1.732 constants, grade/slope), blueprints, codes.

B — Water Supply and Distribution: ~28 questions (22%). Pipe materials, joining methods, valves, water heaters, backflow prevention (RPZ, DCVA, AVB), water treatment, booster pumps.

C — Drain, Waste, and Vent (DWV): ~31 questions (25%). Largest section. Traps, fixture units, pipe sizing, venting methods (individual, common, wet, circuit, island), cleanouts, storm drainage, sewage ejectors.

D — Plumbing Fixtures and Appliances: ~18 questions (14%). Toilets, urinals, sinks, bathtubs, showers, accessibility.

E — Hydronic Heating: ~13 questions (10%). Boiler connections, expansion tanks, circulators, radiant floor, baseboard.

F — Special Systems: ~16 questions (13%). Medical gas, private water/sewage, rainwater harvesting, greywater, natural gas piping, fire suppression.

DWV (C) and Water Supply (B) together account for 47%.

Where Candidates Lose Marks

Venting rules (wet venting, circuit venting, island venting). Backflow prevention device selection (5 device types, hazard levels). Trade math (offset constants, grade calculations). For trade qualifier eligibility, see our article on trade qualifier vs apprentice pathways.

The Plumber Journeyman Red Seal Exam Prep book gives you 1,000 practice questions across 8 full-length tests.

[Get the Plumber Exam Prep book on Amazon →]

[See the full Plumber trade page → /plumber/]

Frequently Asked Questions

How many questions?

[VERIFY] 125 multiple-choice questions. 4 hours. 70% pass mark.

What codes are tested?

National Plumbing Code of Canada. Sizing tables, venting rules, DWV requirements, backflow standards.

Is venting the hardest section?

Yes — consistently cited by candidates as the most difficult area. The rules for wet, circuit, and island venting are complex and vary by fixture group.