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Straight answers
The questions people ask most about getting certified and starting and running a plumbing business in Ontario. Answered straight, with links to the official sources.
Service makes you a faster, more well-rounded plumber (you see everything break) and is the path to your own service business — but the on-call and customer pressure aren't for everyone. New construction is more repetitive and crew-based with cleaner hours. Many start in new construction for the volume and move to service for the money and independence.
On-call pays — premiums, callout minimums, and overtime add up — but it taxes your life: 2am sewage backups and ruined weekends are the trade-off. Early on it accelerates your learning and income; long-term, it's a big reason plumbers move toward day-shift service management or running their own shop where they control the rotation.
Residential is service-heavy, easier to enter, and the natural launchpad for your own business. Commercial and industrial pay more and run bigger, code-intensive projects (process piping, institutional, high-rise) but you specialize narrower. The 306A ticket works across both, so you can switch.
Only to touch gas — but so much residential mechanical work is gas water heaters and boilers that a lot of plumbers add a TSSA gas ticket (G3, then G2). It widens what you can service and is close to mandatory if you want the full residential service market.
The drain and sewer side has genuinely rough moments — that's real. But most of the work is clean install and service, and the "gross" jobs are usually the best-paid emergency calls. Plumbers tend to make peace with it fast; the paycheque helps.
Once you can diagnose anything, sell a job, and you've got the 306A plus a municipal Master Plumber licence to pull permits. The thing that sinks first-year plumbing businesses isn't skill — it's underpricing and cash flow. If you'd rather just turn wrenches and go home, staying a journeyperson is excellent, low-stress money.
Yes — plumber (306A) is a compulsory trade. You must hold a 306A Certificate of Qualification, or be a registered apprentice working under a certified plumber, to do plumbing work. To pull plumbing permits in many cities you also need a municipal Master Plumber licence.
Hold a 306A certificate (or employ a certified plumber), incorporate, register for WSIB and CRA accounts, get $2M liability insurance, and obtain your municipality's Master Plumber / plumbing contractor licence so you can pull permits. Add a TSSA gas ticket if you will connect gas appliances and backflow certification for cross-connection work.
A Master Plumber licence is a municipal credential (not a provincial one) that lets a plumbing business pull plumbing permits in that municipality. Toronto and several other cities require it. It is separate from your 306A Certificate of Qualification — the 306A lets you do the work, the Master Plumber licence lets your business permit it.
The 306A apprenticeship is roughly 9,000 hours (about 5 years) of combined on-the-job and in-school training, after which you challenge the Certificate of Qualification exam. Many start as apprentices and earn while they train.
Only to work on gas. Connecting or servicing gas-fired appliances (water heaters, boilers) requires a TSSA gas fitter certificate (G3, G2, or G1). Many plumbers add a gas ticket because so much residential mechanical work involves gas water heaters and boilers.
A sole proprietorship is cheaper and simpler to start, but you are personally liable for the business's debts and claims. Incorporating creates a separate legal entity that limits personal liability, can reduce tax once you are profitable, and reads as more credible to larger clients. Most contractors incorporate once they have employees, real revenue, or work on others' property.
Yes — construction is a mandatory WSIB sector in Ontario. Even independent operators and partners with no employees generally must register, and clients and general contractors will require a valid WSIB clearance certificate before you can work on their site.
You must register for and charge HST once your revenue exceeds $30,000 over four consecutive quarters. Many contractors register before that threshold so they can claim input tax credits on tools, materials, and vehicles from day one.
Ontario's Construction Act sets the rules: a 10% holdback on most contracts, prompt-payment timelines (you must be paid within set periods after a proper invoice), and an adjudication process for disputes. Understanding holdback, lien rights, and prompt payment is essential to protecting your cash flow.