Replacing a toilet is one of the most approachable plumbing jobs in the house. There is no soldering, no wall to open and only one connection that has to be right. A first-timer with a wrench, a level and a Saturday morning can do it in two to three hours, and a plumber does it in one. This guide covers the whole job in order: removal, the flange (where most problems hide), the seal, setting the bowl, connecting the tank and supply, and testing. At the end is an honest look at what a plumber charges in Ontario and the situations where paying one is the smart move.
Key takeaways
- Buy the toilet after measuring the rough-in (wall to bolt centre, usually 12"). Our rough-in guide shows how.
- The flange must sit on top of the finished floor, or up to 1/4" above it, and be solidly screwed down. A broken or sunken flange is the cause of most leaking toilets.
- Wax ring is the traditional seal and still the most forgiving. Waxless seals are reusable and better for flanges that sit low, or if you might lift the toilet again.
- Set the bowl straight down onto the seal in one motion, press, and never rock it once seated.
- Tighten the closet bolts alternately, snug only. Over-tightening cracks porcelain.
- Ontario plumbers charge roughly $150–$350 to install a toilet you supply, more if the flange needs repair.
Before you buy: three things to check
- Rough-in. Measure from the finished wall (not the baseboard) to the centre of the closet bolts on the existing toilet. 12" is standard; 10" and 14" exist in older homes. A 12" toilet on a 10" rough-in will not fit against the wall.
- Footprint. Note the space on each side (15" minimum from the bolt centre to a wall or fixture, by code) and in front (21" minimum). Elongated bowls are about 2" longer than round ones.
- Supply line position. The shut-off valve on the wall or floor should be to the left of the toilet and low enough not to hit the tank. Skirted toilets sometimes need the valve relocated; check the spec sheet.
Tools and materials
Tools
- Adjustable wrench and a small socket or nut driver (usually 1/2")
- Flat and Phillips screwdrivers
- Putty knife and a plastic scraper
- Torpedo level
- Hacksaw or mini hacksaw (to trim bolts)
- Bucket, sponge, old towels, rubber gloves
- Drill and masonry or wood bits, if the flange needs new screws
Materials
- New toilet (bowl, tank, seat, tank-to-bowl gasket and bolts are in the box)
- Wax ring (or waxless seal) and new brass closet bolts, usually included; buy a spare set anyway ($5)
- New braided stainless supply line, 3/8" compression to 7/8" ballcock, 12"–20" long ($10)
- Flange repair ring or spacer, only if needed ($8–$20)
- Plastic shims and a tube of silicone caulk
Part 1: Remove the old toilet
- Turn off the water at the shut-off valve behind the toilet (clockwise). If it will not close or drips when turned, close the main and plan to replace the valve; a quarter-turn ball valve is $10 and worth doing now.
- Empty the tank and bowl. Flush and hold the handle. Sponge the tank dry. Plunge the bowl to push the water down the drain, then sponge out the rest. A wet/dry vacuum makes this painless.
- Disconnect the supply line from the bottom of the tank. Have a towel ready.
- Remove the tank if it is a two-piece: undo the two or three tank bolts from below with a wrench while holding the bolt head inside the tank with a screwdriver. Lift the tank off. On a one-piece toilet, skip this.
- Pry off the bolt caps at the base and undo the nuts on the closet bolts. If they are rusted solid, cut the bolts with a hacksaw between the nut and the porcelain.
- Break the seal. Rock the bowl gently side to side to free the old wax, then lift it straight up. Two-piece bowls weigh 25–35 kg; one-piece toilets 40–55 kg. Get help, and set it on cardboard.
- Stuff a rag into the drain immediately. It blocks sewer gas and stops anything falling in. Do not forget it is there.
- Scrape off the old wax from the flange with the putty knife. All of it. Old wax will not seal against new wax.
Part 2: Inspect and fix the flange
This is the step that separates a toilet that lasts twenty years from one that leaks at the base in six months. Look at the flange with a flashlight.
| What you see | What to do |
|---|---|
| Flange sits flat on the finished floor, or up to 1/4" above, screwed down tight, no cracks | Perfect. Slide new closet bolts into the slots and go to Part 3. |
| Flange is loose or the screws spin | Drive new #10 stainless screws into solid subfloor (or Tapcons into concrete). A loose flange lets the toilet rock and breaks the seal. |
| Flange sits below the finished floor (common after new tile is laid over the old floor) | Add a flange extender ring or spacer to bring it up, sealed with silicone between layers, or use an extra-thick wax ring / a waxless seal with a deep skirt. Never stack two wax rings. |
| One side of the flange ring is broken where the bolt slot was | A stainless repair ring ($8) screws over the old flange and gives new bolt slots. Ten-minute fix. |
| Cast-iron flange badly corroded, or PVC flange cracked through | Replacement flange. PVC flanges are cut off and a new one glued on; cast iron needs a plumber with the right tools. |
| Subfloor around the flange is soft, dark or spongy | Water damage from a past leak. The subfloor section must be replaced before a toilet goes back. Stop and get a contractor. |
Set the new closet bolts in the flange slots, pointing straight up, spaced to match the toilet's base holes (measure the base). Many bolt kits include small plastic washers that snap over the flange to hold the bolts upright while you lower the toilet; use them.
Part 3: Choose and place the seal
Wax ring
A ring of petroleum wax that compresses when the toilet is set. It has sealed toilets for a century, tolerates a slightly uneven flange, and costs $3–$8. Choose a standard ring for a flange at floor level and an extra-thick ring for a flange up to 1/2" below the floor. Rings "with a horn" (a plastic funnel) are fine on PVC but can catch on cast-iron flanges; plain rings are the safe default. The downside: it is single-use. If you lift the toilet even once, you need a new ring.
Waxless seal
A rubber gasket, sometimes with a foam collar or a sleeve that pushes into the drain. It costs $10–$20, is repositionable, and does not smear or fail if the bathroom gets hot. It is the better choice for a flange that sits low (the sleeve reaches into the pipe), for radiant-heated floors, and for anyone who expects to remove the toilet again (for flooring, for example). It is less forgiving of a flange that is badly out of level.
- Remove the rag from the drain.
- Wax ring: press it onto the flange, centred over the opening, at room temperature (a cold ring cracks; a hot one slumps). Some installers prefer to press it onto the toilet outlet instead; either works if the toilet goes straight down.
- Waxless seal: follow the package. Most press onto the toilet outlet and the sleeve goes into the drain as the toilet is set.
Part 4: Set the bowl
- With a helper, lift the bowl (or the whole one-piece toilet) and hold it directly over the flange, bolt holes lined up over the bolts. Sight down through the holes.
- Lower it straight down in one motion. Do not slide it into position, and do not tilt it. If you miss the bolts, lift straight up, reposition, and use a fresh wax ring if the old one has been compressed.
- Once it is down, press firmly with your full body weight straight down over the outlet, then sit on it. This compresses the seal. Do not twist or rock.
- Slip the plastic cap bases, washers and nuts onto the bolts. Tighten alternately, a few turns each side, until snug. Then a quarter turn more. Stop. If you hear anything, stop sooner.
- Check the level side to side and front to back. If it rocks, slide plastic shims under the low side (never over-tighten to fix a rock), then trim the shims flush with a utility knife.
- Cut the bolts about 1/2" above the nuts with the mini hacksaw and snap the caps on.
Part 5: Install the tank (two-piece toilets)
- Fit the large rubber tank-to-bowl gasket over the flush valve outlet on the underside of the tank.
- Push the tank bolts through the tank from the inside, with a rubber washer under each bolt head inside the tank.
- Lower the tank onto the bowl so the bolts pass through the bowl's holes.
- From below, add the washers and nuts. Tighten alternately, a little at a time, keeping the tank level, until the tank sits firmly on the gasket and does not wobble. The tank should not touch the porcelain of the bowl except through the gasket. Do not crank; porcelain again.
- Some tanks are pre-assembled or use a three-bolt pattern; follow the diagram in the box.
Part 6: Connect the supply and test
- Thread the new braided supply line onto the fill valve shank under the tank, hand-tight plus a quarter turn. No tape or dope on these compression fittings.
- Connect the other end to the shut-off valve the same way.
- Open the valve slowly. Watch the connections and the base while the tank fills.
- Adjust the fill valve so the water sits about 2.5 cm below the overflow tube.
- Flush five or six times. After each flush, run a dry paper towel around the base and under the tank. Any dampness at the base means the seal did not take: the toilet has to come up and a new ring go in.
- Install the seat: bolts through the hinges, nuts snug from below (or top-fix per the instructions).
- Wait a day, check again, then run a thin bead of silicone caulk around the base, leaving a 2"–3" gap at the back. Caulk is required by the Ontario Building Code for hygiene; the gap lets a future leak show itself instead of hiding under the toilet.
Toilet installation cost in Ontario
| Item | DIY | Plumber (GTA, Ottawa, Hamilton) |
|---|---|---|
| Straight swap, same rough-in, good flange (toilet supplied by you) | $20–$40 in seal, bolts and supply line | $150–$350 |
| Flange repair ring or extender | + $8–$20 | + $50–$150 |
| Flange replacement (PVC) | + $20, advanced DIY | + $150–$400 |
| Replace the shut-off valve | + $10–$15 (push-fit valve) | + $75–$150 |
| Haul away the old toilet | Municipal bulk pickup, often free | $25–$75 |
| Moving the drain to a new rough-in | Not a DIY job | $800–$2,500+, floor opened |
| Wall-hung toilet with in-wall carrier | Not a DIY job for most | $800–$1,500 labour, wall open |
Add HST. Most plumbers quote a flat rate for a standard swap and charge hourly ($110–$175/hr) when they find a problem. A new toilet itself runs $200–$500 for a quality dual-flush one-piece and $500–$1,000 for a premium rimless model.
When to call a plumber instead
- The flange is cast iron and damaged, or sits more than 1/2" below the floor.
- The subfloor around the toilet is soft.
- The shut-off valve is seized and you are not comfortable working at the main.
- You are changing the rough-in, moving the toilet, or installing a wall-hung unit.
- The house has old galvanized or lead supply lines.
- You have set the toilet twice and it still leaks at the base. Something is wrong with the flange height, and a plumber will diagnose it in minutes.
Choosing the replacement toilet
If you are doing the work anyway, install something better than what came out. Look for a fully glazed 2" or larger trapway, a MaP score of 800 g or more, a 3" flush valve, and dual flush. One-piece toilets skip Part 5 entirely and have no tank gasket to leak. Our dual-flush guide and rough-in guide cover the details.
Shop toilets at MyBath
One-piece, two-piece, wall-hung and smart toilets from MyBath, Toto and Duravit, delivered across Ontario. Free delivery on orders over $600 within Ontario.
Frequently asked questions
How long does it take to install a toilet?
About an hour for a plumber and two to three hours for a first-time DIYer, including removing the old toilet. A flange repair adds 30–60 minutes.
How much does it cost to have a toilet installed in Ontario?
$150–$350 plus HST for a straightforward swap where you supply the toilet. Flange repairs, valve replacement and disposal add $50–$400. A new toilet is $200–$1,000 on top.
Wax ring or waxless seal?
Wax is cheap, forgiving of an uneven flange, and proven; it is single-use. Waxless seals are reusable, better for low flanges and heated floors, and worth the extra $10 if you might lift the toilet again.
Why does my new toilet rock?
The floor or flange is not level. Shim the low side with plastic shims and trim them flush. Do not tighten the bolts harder; that cracks the base.
Why is my new toilet leaking at the base?
The seal did not compress properly, usually because the flange sits too low, the toilet was slid or rocked into place, or old wax was left on the flange. Lift the toilet, fix the flange height, and reset it with a fresh ring.
Should I caulk around the base of the toilet?
Yes. The Ontario Building Code requires it for hygiene. Leave a gap of a few centimetres at the back so a future leak drains out where you can see it instead of soaking the subfloor.
