To check if a plumber is registered in Ontario, ask for their Certificate of Qualification number for trade code 306A (Plumber) and look it up on the Skilled Trades Ontario public register at skilledtradesontario.ca — the search is free, takes under two minutes, and confirms whether the certificate is active, expired, or nonexistent. Plumbing is a compulsory trade in Ontario, which means it is illegal for anyone to work as a plumber without either a valid 306A certificate or a registered apprenticeship with a certified journeyperson supervising. Beyond the certificate, a proper check in 2026 a...
Skilled Trades Ontario is the provincial agency that issues and tracks trade certifications, and its public register is the single authoritative source for confirming a plumber's credentials. Ask the plumber for the exact name on their certificate and their certificate or membership number, then search the register on skilledtradesontario.ca. A valid result shows the tradesperson's name, the trade (306A Plumber), and the status of the certificate. What you want to see is an active, in-good-standing certificate. If the search returns nothing, the person is not certified under that name — which may mean they are an apprentice, working under someone else's certificate, or not qualified at all. Note that the register covers individual people, not companies: a plumbing company can be perfectly legitimate while employing certified journeypersons and apprentices, so if the company owner isn't listed, ask which certified plumber will actually be on site and verify that person instead.
Plumber (306A) is a compulsory trade in Ontario, unlike many voluntary construction trades. Compulsory status means certification is legally required to perform the work, and enforcement officers can issue penalties for uncertified plumbing work. Handyman-style plumbing by an uncertified person is not legal, regardless of how skilled they claim to be.
A WSIB clearance certificate proves the plumber's workplace insurance account is in good standing and, critically, protects you as the homeowner. If an uninsured worker is injured in your home, you can be exposed to liability for their injury costs. Clearance certificates are free and can be requested by anyone through the WSIB website using the business's legal name or account number, so you don't have to take the plumber's word for it. Independent operators with no employees may hold optional coverage rather than mandatory coverage; in that case ask for proof of their own personal accident or disability insurance instead. Certificates are time-limited, so check the validity dates and make sure the certificate covers the period your work will happen. Any plumber who resists providing a clearance certificate — a routine, no-cost document that professionals produce daily for commercial clients — is telling you something important about how they run their business.
Ask for a certificate of insurance issued directly by the plumber's insurance broker, not a photocopied card. In Ontario, $2 million in commercial general liability is the standard minimum for residential plumbing work, and the certificate should show the policy number, coverage limits, and expiry date. Next, check the HST number on the quote: any business in Canada earning more than $30,000 annually must register and charge HST, and you can validate a GST/HST number free through the Canada Revenue Agency's registry. A plumber charging HST without a valid number is a serious red flag. Finally, insist on a written contract before work begins. Under Ontario's Consumer Protection Act, direct agreements over $50 signed in your home must be in writing and give you a 10-day cooling-off period to cancel without penalty. The contract should list the scope, materials, total price, payment schedule, and warranty. Never pay the full amount up front — a deposit of 10–30% is normal, with the balance on completion.
Cash-only demands, requests for 50%+ up front, and pressure to sign immediately are the three most common patterns in Ottawa plumbing scams. Pay by credit card, cheque, or e-transfer so there's a record, and keep every receipt for warranty claims.
A 306A plumbing certificate does not authorize gas work. If your job involves a gas water heater, gas boiler, gas line for a range or barbecue, or a gas furnace connection, the person doing that portion must hold a TSSA-issued gas technician certificate (G3, G2, or G1, in increasing order of scope). The Technical Standards and Safety Authority maintains the registry and lets you confirm a certificate is valid. Many Ottawa plumbers hold both credentials, but plenty hold only one, and gas work performed by an uncertified person is both illegal and dangerous — it can also void your home insurance if an incident occurs. The same separation applies to electrical: connecting an electric water heater or a sump pump circuit is licensed electrician territory under the Electrical Safety Authority, not plumbing. Our Ottawa electrical permit and ESA guide explains how that side of the verification works and when an ESA notification is required.
In Ottawa, many plumbing jobs require a plumbing permit from the City — typically anything that alters, extends, or adds to the drain, waste, vent, or water distribution system, such as moving a bathroom, adding a basement bathroom, replacing a water service, or installing a backwater valve. Simple fixture swaps like replacing an existing faucet or toilet in the same location generally don't. A licensed plumber will pull the permit as part of their scope and arrange the City inspection; that inspection is your independent, third-party verification that the work meets the Ontario Building Code. If a plumber suggests skipping the permit to save money, decline — unpermitted plumbing surfaces later during a home sale, can complicate insurance claims after a water loss, and leaves you responsible for corrections. Confirm in writing who pulls the permit and who pays for it, and ask to see the closed inspection before making the final payment. Our Ottawa plumbing permit guide details which jobs need one and what the City charges.
Ottawa's Residential Protective Plumbing Program has historically offered grants toward backwater valves, sump pumps, and related flood protection — but eligibility requires a permitted, inspected installation by a licensed plumber. Skipping the permit forfeits the rebate.
Ask for the plumber's Certificate of Qualification number for trade 306A and search it free on the Skilled Trades Ontario public register at skilledtradesontario.ca. An active certificate confirms they are legally qualified. The register lists individuals, so if you're hiring a company, verify the certified plumber who will actually be on site.
Yes. Plumber (306A) is one of Ontario's compulsory trades, meaning it is illegal to perform plumbing work without a valid Certificate of Qualification or a registered apprenticeship supervised by a certified journeyperson. Uncertified plumbing work can result in penalties and is not covered by most warranties or insurance.
At minimum, $2 million in commercial general liability insurance plus WSIB coverage. Request a certificate of insurance directly from their broker and a free WSIB clearance certificate through the WSIB website. Independent operators without employees may carry optional WSIB coverage instead, so ask what protection they hold.
Only if they also hold a TSSA gas technician certificate (G3, G2, or G1). A 306A plumbing certificate does not authorize gas piping, gas water heater, or gas boiler connections. Verify gas credentials separately through the Technical Standards and Safety Authority before any gas appliance work.
Usually yes for anything that alters, adds to, or extends drain, waste, vent, or water supply piping — including basement bathrooms, relocated fixtures, water service replacement, and backwater valves. Straight fixture replacements in the same location generally don't. Your licensed plumber should pull the permit and arrange the City inspection.
Don't hire them. If work has already been done and you suspect the plumber wasn't certified, you can report the concern to Skilled Trades Ontario or the Ministry of Labour, contact the City of Ottawa if the work was unpermitted, and file a complaint with Consumer Protection Ontario. Remember that in-home contracts over $50 carry a 10-day cooling-off period.