Plumbing is one of the trades Ontario takes seriously enough to restrict by law. A person doing plumbing work for hire must hold a Certificate of Qualification in the 306A Plumber trade, which means they completed an apprenticeship and passed a provincial exam. This is not a formality. It is the difference between a repair your insurer will cover and one they will argue about.
That said, most plumbing calls are small. A running toilet or a slow drain does not require you to interview three companies. The guidance below scales: use the quick checks for small jobs, and the full list when the work involves opening walls, moving fixtures, or replacing anything connected to your water supply or gas line.
What plumbers do
- Repairing and replacing fixtures - toilets, sinks, tubs, showers, faucets
- Water heater replacement, including tankless conversions
- Drain clearing, camera inspection, and drain replacement
- Rough-in plumbing for new bathrooms, kitchens and basement builds
- Water supply lines, shut-off valves and pressure regulators
- Sump pumps, backwater valves and basement flood prevention
Does a plumber need a licence in Ontario?
Yes. Plumber (306A) is a compulsory trade in Ontario - working without certification is illegal, not just inadvisable.
Certificate of Qualification, 306A Plumber
The individual doing the work must hold this, or be a registered apprentice working under someone who does. Ask for the certificate number and the name it is issued to. It belongs to a person, not a company.
Verify with: Skilled Trades Ontario maintains the public register of certified tradespeople.
Open the official lookupGeneral liability insurance
Two million dollars is the common floor for residential work. Water damage escalates fast, and a burst supply line during a renovation can exceed a small policy in an afternoon.
WSIB clearance
If a worker is injured on your property and the contractor has no coverage, you can be drawn into the claim. A clearance certificate is free for the contractor to pull and takes minutes.
Verify with: WSIB issues clearance certificates directly to the contractor on request.
Open the official lookupTSSA gas technician certificate (only if gas is involved)
G1, G2 or G3 depending on scope. Required for anything connecting to a natural gas or propane line.
Verify with: The Technical Standards and Safety Authority regulates fuel safety in Ontario.
Open the official lookupWhat it costs in Ontario
Plumbing pricing splits into two models: a flat rate per job, or a service call fee plus hourly. Flat rate is usually better for you on straightforward work because the risk of a slow day sits with the contractor. Ask which model you are being quoted under before comparing two numbers.
| Job | Typical range |
|---|---|
| Service call / diagnostic visitOften credited against the repair if you proceed. Ask whether it is. | $90 – $180 |
| Hourly rate (after the call-out)Higher end for emergency, evening and weekend work. | $95 – $175 / hour |
| Clear a blocked drainSnaking a simple clog sits at the low end; hydro-jetting or a camera inspection pushes it up. | $150 – $450 |
| Replace a toiletIncludes a mid-range fixture and removal of the old one. | $350 – $800 |
| Water heater replacement (tank, gas)Installed and vented. Rental buyouts are separate - check who owns your current tank. | $1,800 – $3,200 |
| Tankless water heater conversionHigher because it usually needs new venting and a gas line upsize. | $4,000 – $7,000 |
| Sump pump supply and installBattery backup adds roughly $600 to $1,200. | $700 – $1,800 |
| Repipe a typical house in PEXDepends heavily on how much drywall has to come out and go back. | $6,000 – $15,000 |
These are planning estimates for Ontario, not quotes, and they move with material prices and demand. Use them to sanity-check a quote, not to argue one down.
Questions to ask before you hire
- 1Is the person doing the work certified in 306A, or an apprentice being supervised? Both are fine. You just want to know.
- 2Is this quote flat rate or time and materials? If hourly, what is the estimated range and what happens if it runs over?
- 3Does the job touch a gas line, and if so who holds the TSSA certificate?
- 4Does this need a municipal plumbing permit, and are you pulling it?
- 5What is the warranty on labour, separately from the manufacturer warranty on parts?
- 6If you open a wall to reach the pipe, is patching and painting included or is that on me?
Warning signs
- A quote given over the phone for work nobody has looked at, on anything more involved than a fixture swap.
- Reluctance to give a certificate number when asked directly. Certified plumbers are used to this question.
- Pressure to decide immediately because of a "crew in the area today".
- Cash-only pricing framed as a discount. You lose your warranty, your paper trail, and your recourse.
- A large deposit up front. Materials deposits are normal on big jobs; half the job value before anyone starts is not.
How to read reviews for this trade
Plumbing reviews skew emergency-heavy, which makes them unusually harsh. People write reviews when their basement is wet. Read the three-star reviews rather than the one-star ones: they tend to describe what actually happened rather than how it felt. Consistency of response time matters more here than in most trades.
Some of this you can do yourself
Not every job in this trade needs a contractor. These guides cover the ones that do not, and say plainly where to stop.