Toilet installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What toilet installation is

Toilet installation removes an old toilet and sets a new one, with a new wax or foam seal, a supply line and a check that the floor is solid and the toilet sits level. Many homeowners call when a toilet has cracked, rocks on the floor, or leaks at the base in a way a repair cannot stop.

Signs you need it

  • The toilet rocks when you sit on it, which can mean the flange is broken or the floor under the base has softened
  • Water seeps from the base of the toilet, or the floor around it is soft or smells of sewer
  • The tank or bowl is cracked, or the bowl has stains that cleaning cannot remove
  • The toilet is an older high-flow model that wastes water, and you want a more efficient bowl
  • The old toilet has a different rough-in or height than you want, and the layout is changing

What the pro does

  • Shut off the supply, flush, and disconnect the supply line, then remove the tank and bowl bolts and lift the old bowl
  • Inspect the closet flange and the floor under the base for cracks, rot and height, and repair or replace the flange if needed
  • Set a new wax ring or a wax-free seal on the flange, and place the new bowl with the bolts correctly positioned
  • Level the bowl with plastic shims, tighten the bolts evenly, and check that the bowl does not rock
  • Install the tank, the tank-to-bowl gasket, and the supply line with a shutoff valve
  • Turn the water on, flush several times, and check the base and supply connection for leaks

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Condition of the closet flange and subfloor, since a broken flange or soft floor adds work
  • Rough-in distance from the wall to the bolt centers, which must match the new toilet
  • Whether the shutoff valve or supply line is replaced as part of the install
  • Type of toilet: a one-piece, two-piece, or comfort-height bowl changes the install
  • Access to the bathroom and whether any tile or flooring must be cut around the base
  • Disposal of the old toilet and whether a new floor finish is needed

What a written quote should spell out

  • Make and model of the new toilet, and whether the seal is wax or wax-free
  • Flange repair or replacement, if needed, and the material used
  • Supply line and shutoff valve, new or reused
  • Floor condition at the base, and what is done if the subfloor is soft
  • Whether the install includes caulk at the base and the cleanup

Questions to ask before you hire

  • Is the closet flange in good shape, and will you replace it if it is cracked or set too low?
  • What seal do you use, and why for this floor?
  • What is the rough-in distance, and does the new toilet fit it?
  • Will you check the subfloor for soft spots once the old toilet is off?
  • Do you replace the supply line and shutoff valve?
  • Will the toilet be level and solid when you leave, and how will you check it?

Red flags

  • Pro who sets a new bowl on a cracked or low flange without repairing it
  • Pro who tightens the bolts down hard to stop a rock instead of shimming the bowl
  • Pro who reuses a wax ring that has already been compressed on the old bowl
  • Pro who does not check the subfloor when the old toilet shows signs of rot

What you can do yourself

A homeowner can replace a toilet on a sound floor if the flange and subfloor are in good condition and the supply and drain are accessible. Stop and call a pro if the flange is cracked, the floor is soft, or the bowl will not set level, since a loose toilet leaks at the base and can rot the floor.

Licenses and permits

Toilet installation is commonly done by licensed plumbers in many areas, and a replacement that changes the drain or the flange may need a permit. Check with your state or local licensing agency to confirm what applies to your job.

Toilet installation questions

Do I need a new wax ring every time?

Yes. A wax ring compresses once and does not return to shape, so reusing it is a common cause of leaks. Use a new seal, or a wax-free seal, when you set a toilet.

Why does my new toilet rock?

A rock usually comes from an uneven floor, a low or cracked flange, or bolts tightened unevenly. Shimming the base and checking the flange fixes most rocks without overtightening.

How do I know the subfloor is soft?

Press on the floor around the base. Spongy floor, soft spots, or a sewer smell suggest rot or water damage. A pro checks the subfloor once the old toilet is off.

Should I replace the supply line when I replace the toilet?

It is a good time to. Supply lines age and can burst, and replacing them while the toilet is out adds little time and prevents a common leak.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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