Certifying authority: Skilled Trades Ontario (STO). Last checked 2026-09-10.
This trade is on Ontario’s compulsory list as Plumber (306A). Under Skilled Trades Ontario, workers must hold a valid Certificate of Qualification, a Provisional Certificate of Qualification, or a Registered Training Agreement; journeypersons must renew their C of Q each year. Official list PDF is dated Feb 2022; the count of 23 still matches the current STO page.
Source: Skilled Trades Ontario — Compulsory Trades (23 trades)
Whether it is required or not, the exam itself is the same paper everywhere in Canada. What your province decides is whether you must hold the certificate, how you apply, and where you sit it.
The Red Seal Occupational Standard sets the split below. It does not change by province.
| Major Work Activity | Weighting | Questions |
|---|---|---|
| MWA A: Performs common occupational skills | 11% | 14 Qs |
| MWA B: Prepares and assembles tube, tubing and pipe | 10% | 13 Qs |
| MWA C: Installs, tests and services sewers, sewage treatment systems and drainage, waste and vent (DWV) systems | 26% | 32 Qs |
| MWA D: Installs, tests and services water service and distribution | 19% | 24 Qs |
| MWA E: Installs, tests and services fixtures, appliances and water treatment systems | 14% | 17 Qs |
| MWA F: Installs, tests and services low-pressure steam and hydronic systems | 13% | 16 Qs |
| MWA G: Installs, tests and services specialized systems | 7% | 9 Qs |
Source: Red Seal Exam Breakdown — Plumber, red-seal.ca
4 hours, and a 70% pass mark. These are set provincially rather than by the Red Seal standard, and the four hours is the same whether your paper is 100 or 150 questions.
Confirmed against Skilled Trades Ontario’s Exam Preparation Guide and SkilledTradesBC. Check your own authority before exam day.
Booking is handled by Skilled Trades Ontario (STO); confirm current locations and dates with them.
Our Plumber bank is built to the weighting above, with a worked explanation on every question.
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