How to Hire a Plumber in Ontario
To hire a plumber in Ontario, first confirm they can legally work in the trade: plumbing is a compulsory trade, so a qualified plumber appears on the Skilled Trades Ontario Public Register. Then ask for a current WSIB clearance certificate and proof of liability insurance (ProScore suggests at least $2M), get two or three written, itemized quotes for any job over $500, and agree in writing who pulls the permit.
How Ontario plumbers compare on ProScore
ProScore lists 2,001 plumbers in Ontario, and has published a ProScore for 1,818 of them. 724 of those reach Trusted (70+) or higher. ProScore matched 582 of them (29%) to the WSIB register by business name. A business that is not matched may still be covered, so ask any plumber you are considering for a current WSIB clearance certificate.
Counted from ProScore's current listings, refreshed daily. How ProScore scores
Hiring Checklist
What Ontario's rules say
- Under O. Reg. 215/01, only a certified gas technician may install, service or repair a natural gas or propane appliance such as a furnace; a G.2 certificate covers appliances of 400,000 Btu/h or less. Government of Ontario
- To qualify for Toronto's subsidy, the contractor must hold a valid City of Toronto business licence when the work is done, and a backwater valve needs a building permit and an inspection before it is covered up. City of Toronto
- Plumber is a compulsory trade in Ontario: to work legally, a plumber must hold a Certificate of Qualification, a Provisional Certificate of Qualification or a registered training agreement, and must appear on the Skilled Trades Ontario Public Register. Skilled Trades Ontario
- Search the Skilled Trades Ontario Public Register by name or Skilled Trades Ontario ID to confirm a plumber can legally work in the trade. Skilled Trades Ontario
- If an estimate is part of your contract, Ontario's Consumer Protection Act bars the contractor from charging more than 10% above it unless you agree to new work or a new price and sign a change to the contract. Government of Ontario
Red Flags to Watch For
Demands full payment upfront
Standard practice is a deposit (10–30%) with the balance on completion. Full payment upfront removes all leverage.
No written quote or contract
Professional plumbers provide detailed written quotes. If they refuse, walk away.
Cannot provide licence number
Any legitimate plumber will readily share their Skilled Trades Ontario registration number.
Pressure to decide immediately
“This price is only good today” is a high-pressure sales tactic. Reputable plumbers give you time to compare.
No business address or website
Legitimate plumbing companies have a physical address and online presence. Fly-by-night operators do not.
Unusually low quote
If one quote is 40%+ below others, they may be cutting corners on materials, skipping permits, or planning to upsell.
Questions to Ask Before Hiring
“Are you licensed with Skilled Trades Ontario?”
“What does your quote include?”
“How do you handle unexpected issues?”
“What warranty do you provide?”
“Can I see your insurance certificate?”
Licensing: Skilled Trades Ontario
Ontario plumbers must hold a Certificate of Qualification (C of Q) from Skilled Trades Ontario. This ensures they have completed a formal apprenticeship and passed provincial exams. You can verify any plumber’s credentials on the Skilled Trades Ontario website.
Verify at Skilled Trades Ontario →Frequently Asked Questions
Do plumbers need to be licensed in Ontario?
Yes. Plumbing is a compulsory trade in Ontario, meaning only those with a Certificate of Qualification can legally perform plumbing work.
How many quotes should I get?
Get at least 2–3 written quotes for any job over $500. This ensures you understand the fair market rate and can compare scope.
What should a plumbing quote include?
A detailed breakdown of labour, materials, permits, disposal fees, timeline, and warranty terms. Avoid vague lump-sum quotes.
Can I do my own plumbing in Ontario?
Homeowners can do minor plumbing in their own primary residence, but anything involving permits, gas lines, or backflow prevention must be done by a licensed plumber.
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Sources
- Government of Ontario, O. Reg. 215/01: Fuel Industry Certificates. Accessed October 19, 2026.
- City of Toronto, Basement Flooding Protection Subsidy Program (Page modified June 18, 2026). Accessed October 19, 2026.
- Skilled Trades Ontario, Plumber (trade information). Accessed October 19, 2026.
- Skilled Trades Ontario, Public Register. Accessed October 19, 2026.
- Government of Ontario, Your rights when starting home renovations or repairs (Updated August 6, 2026). Accessed October 19, 2026.
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