How do I properly install a new toilet?

1. Prepare the installation area

1. Turn off the water supply valve.
2. Flush the old toilet and remove as much water as possible from the tank and bowl.
3. Disconnect the water supply line.
4. Remove the old toilet by taking off the nuts on the floor bolts and lifting the bowl straight up.
5. Stuff a rag into the drain opening temporarily to block sewer gases and keep debris out.Lowe's+1

2. Inspect the flange

The flange is the ring on the floor that connects the toilet to the drain and holds the toilet bolts.

Check that:

• It is firmly attached to the floor.
• It is not cracked, broken, or badly corroded.
• It sits at the correct height relative to the finished floor.

If the flange is damaged or loose, repair it before installing the toilet. A toilet can leak or rock if the flange does not support it properly.This Old House+1

3. Install the closet bolts

• Slide the new bolts into the flange slots.
• Position them so they line up with the holes in the toilet base.
• Hold them upright with washers or retaining clips if supplied.

4. Install the wax ring

• Clean old wax from the flange area.
• Center the new wax ring on the flange (or install it on the toilet outlet if the manufacturer recommends that method).
• Do not reuse the old wax ring.Lowe's+1

5. Set the toilet bowl

1. Remove the rag from the drain.
2. Carefully lower the bowl straight down over the bolts.
3. Press down firmly to compress the wax ring.
4. Check that the bowl sits flat and does not rock.
5. Add washers and nuts to the bolts.
6. Tighten each side gradually, alternating back and forth.

Do not overtighten—too much force can crack the porcelain.This Old House+1

6. Attach the tank (if it is a two-piece toilet)

• Install the rubber tank-to-bowl gasket.
• Insert the tank bolts.
• Tighten evenly until the tank is secure and does not wobble.
• Avoid excessive tightening, which can damage the tank.Home Depot

7. Connect the water supply

• Attach the new supply line (a new line is often a good idea when replacing a toilet).
• Hand-tighten, then snug slightly with a wrench.
• Slowly open the shutoff valve.
• Let the tank fill and check for leaks.Lowe's

8. Test and finish

• Flush several times.
• Check around the base for water leaks.
• Check the supply connection and tank bolts.
• Install the seat.
• Trim excess closet bolts and install caps.
• Caulk around the base if required by your local practice/code, often leaving a small opening at the back so a hidden leak can be noticed.Lowe's+1

Common mistakes to avoid

• ❌ Reusing the old wax ring
• ❌ Setting the toilet down crooked and trying to reposition it after the wax compresses
• ❌ Tightening bolts too much
• ❌ Ignoring a damaged flange
• ❌ Using a toilet that rocks instead of fixing the leveling issue

If you are replacing an existing toilet with the same rough-in size (commonly 12 inches from the wall to the center of the flange), the job is usually much simpler. If you’re installing where there was no toilet before, the plumbing work is a different level of project.

Would you like tips on how to remove a stubborn, rusted floor bolt or recommendations on choosing the right wax ring for your floor height?

1. Prepare the area

1. Turn off the water supply valve.
2. Flush the old toilet and remove as much water as possible from the tank and bowl.
3. Disconnect the water supply line.
4. Remove the old toilet by loosening the bolts at the base and lifting it away.
5. Scrape all old wax from the flange and inspect the flange for cracks, rust, or damage. A damaged or loose flange should be repaired before installing the new toilet.The Home Depot+1

2. Check the flange

The toilet flange should be firmly attached to the floor and sit at the correct height relative to the finished floor. It anchors the toilet and provides the connection to the drain.The Home Depot

• Replace broken closet bolts.
• Make sure the flange is not cracked.
• Make sure the floor around it is solid and not water-damaged.

3. Install the wax ring and bowl

1. Insert the new closet bolts into the flange slots.
2. Place the wax ring centered on the flange (or install it on the toilet outlet if your toilet manufacturer recommends that method).
3. Lower the toilet bowl straight down over the bolts.
4. Press down firmly to compress the wax seal.
5. Add washers and nuts, then tighten gradually from side to side. Do not overtighten—porcelain can crack.Lowe's+1

Tip: After the toilet contacts the floor, check it with a level. If it rocks, use toilet shims rather than forcing the bolts tighter.Oatey

4. Attach the tank (for two-piece toilets)

1. Install the rubber tank-to-bowl gasket.
2. Set the tank onto the bowl.
3. Install the tank bolts and tighten evenly.
4. Stop tightening once the tank is secure—too much force can crack the tank or bowl.Fine Homebuilding

5. Connect the water supply

1. Attach the new supply line to the shutoff valve and toilet tank.
2. Open the shutoff valve slowly.
3. Let the tank fill.
4. Flush several times.
5. Check:

• Around the toilet base
• At the tank bolts
• At the supply connection

If water appears at the base after flushing, the wax seal may not be seated correctly and the toilet may need to be removed and reset with a new seal.Lowe's

6. Finish the installation

• Install the toilet seat.
• Trim excess closet bolts and install caps.
• Caulk around the base if desired or required by local practice/code, while leaving a small inspection opening if recommended for leak detection.Lowe's

Common mistakes to avoid

• Reusing an old wax ring
• Setting the toilet down crooked and breaking the seal
• Tightening bolts too much
• Ignoring a damaged flange
• Trying to fix a rocking toilet by simply tightening bolts

If you’re replacing an existing toilet in the same spot, the project is usually much simpler. If you’re moving the toilet location, replacing the flange, or dealing with a concrete floor, the plumbing work becomes significantly more involved.The Home Depot

If you want, tell me:

• Is your old flange flush with the floor or raised/broken?
• Are you installing on a concrete or wood subfloor?

I can give you specific tips for a secure fit.

Before starting, check the toilet manufacturer's installation instructions because some models use a proprietary gasket or mounting system rather than a conventional wax ring.American Standard+1

1. Shut off and drain the old toilet

Turn off the water at the shutoff valve beside the toilet. Flush the toilet and hold the handle down to drain as much water as possible. Sponge out the remaining water from the tank and bowl.

Disconnect the supply line.

2. Remove the old toilet

Remove the caps and nuts from the two floor bolts. Cut through any caulk around the base if necessary.

Rock the toilet gently side-to-side to break the seal, then lift it straight up. Toilets are heavy and awkward, so having another person help is worthwhile.

Immediately stuff a rag into the exposed drain opening to keep sewer gas and debris from entering the room.

3. Inspect the closet flange

Scrape away the old wax/seal and clean the flange.

The flange should be firmly attached to the floor and shouldn't be cracked or badly corroded. If it's damaged, don't simply install the new toilet over it—repair or replace the flange first.

Also check the toilet's rough-in measurement. A common toilet uses a 12-inch rough-in, but don't assume yours does; measure from the finished wall to the center of the flange/bolt location according to the toilet manufacturer's instructions. Many current toilets specify a 12-inch rough-in.American Standard+1

4. Install the new seal and bolts

Put the new closet bolts into the flange slots and position them so they line up with the toilet's mounting holes.

Install the wax ring or manufacturer-specified gasket. With a conventional wax-ring installation, the ring is typically pressed onto the toilet outlet or positioned according to the manufacturer's instructions. American Standard's instructions, for example, call for pressing the wax ring onto the bottom of the bowl before setting it over the bolts.American Standard

Don't reuse the old wax ring.

5. Set the toilet

Remove the rag from the drain.

Carefully lower the toilet straight down over the bolts and onto the seal. Try to get it positioned correctly on the first attempt; repeatedly lifting and resetting a wax-sealed toilet can compromise the seal.

Press down firmly and gently rock it enough to fully seat the seal.

6. Tighten the mounting nuts

Install washers and nuts on the floor bolts.

Tighten them alternately and gradually until the toilet is secure. Don't crank them down aggressively—the porcelain can crack.

If the toilet rocks, use appropriate plastic/composite shims rather than trying to eliminate the rocking by overtightening the bolts.

Trim the excess bolt length and install the decorative caps.

7. Install the tank, if it's a two-piece toilet

If you have a two-piece toilet, install the tank-to-bowl gasket, bolts, washers and nuts according to the manufacturer's instructions.

Tighten evenly until the tank is secure and properly aligned. Again, avoid overtightening porcelain.

8. Connect the water

Attach the new supply line between the shutoff valve and toilet fill valve.

Open the shutoff valve slowly and watch every connection for leaks.

Let the tank fill, then flush several times. Check:

• Around the supply-line connections
• Around the tank-to-bowl connection
• Around the base of the toilet
• Around the flange area, if accessible

9. Check for rocking and leaks

Sit or gently put weight on the toilet and make sure it doesn't move.

Flush repeatedly and inspect the base and connections. If water appears at the base after flushing, stop using the toilet—that can indicate a compromised drain seal or flange problem rather than simply a loose water connection.

Finally, install the seat and, if desired/required by your local practice and the toilet manufacturer, apply a neat bead of bathroom caulk around the base while leaving the appropriate area uncaulked if specified for leak detection.

One important warning

If the existing flange is broken, the floor around it is rotten, the drain pipe is moving, or the new toilet doesn't sit properly over the flange, stop before installing it. Those are plumbing/structural problems that need to be corrected first.

For a conventional toilet, the manufacturer's sequence is essentially: shut off water → install bolts/seal → set bowl → tighten mounting hardware → connect supply → turn water back on and test.American Standard

If you tell me whether you're replacing an old toilet or installing one where there wasn't previously a toilet, I can give you the exact procedure for that situation.

Most residential toilets have a 12-inch rough-in. Measure from the finished wall (not the baseboard) to the center of the floor bolts. Common rough-ins are 10", 12", and 14".Lowe's

Step 2: Remove the old toilet

1. Shut off the water supply.
2. Flush and hold the handle down to empty the tank.
3. Sponge out any remaining water.
4. Disconnect the supply line.
5. Remove the nuts from the floor bolts.
6. Rock the toilet gently to break the wax seal.
7. Lift it off and set it aside.
8. Stuff a rag into the drain opening to block sewer gases.

Step 3: Prepare the flange

• Scrape away all old wax with a putty knife.
• Inspect the flange for cracks or damage.
• Replace broken closet bolts.
• If the flange is damaged, repair or replace it before continuing.The Home Depot+1

Step 4: Install the new seal

Depending on the manufacturer's instructions:

• Place the wax ring on the flange, or
• Attach it to the bottom of the toilet.

Avoid touching or moving the toilet once it compresses the wax ring.

Step 5: Set the toilet

1. Align the bolt holes with the closet bolts.
2. Lower the toilet straight down.
3. Press firmly with your body weight to compress the seal.
4. Check that the toilet sits flat.

If it rocks, insert plastic shims before tightening.

Step 6: Tighten the bolts

• Install washers and nuts.
• Tighten each side a little at a time, alternating back and forth.
• Do not overtighten—you can crack the porcelain.

Trim excess bolt length if necessary and install the caps.

Step 7: Install the tank (two-piece toilets)

• Install the tank gasket.
• Insert the tank bolts.
• Tighten each side evenly until the tank sits securely.
• Don't force the bolts—porcelain breaks easily.Fine Homebuilding+1

Step 8: Connect the water

• Install a new flexible supply line if possible.
• Hand-tighten first, then snug it with a wrench.
• Open the shutoff valve slowly.

Step 9: Test for leaks

Flush several times while checking:

• Around the base
• Under the tank
• At the water supply connection

If the toilet rocks after installation, don't simply tighten the bolts more—shim it as needed.

Step 10: Caulk (optional or code-required)

Practices vary:

• Many plumbers leave a small gap at the back so hidden leaks can escape.
• Some plumbing codes require caulking around the base for sanitation and stability.

Check your local plumbing code before deciding.Fine Homebuilding

Common mistakes to avoid

• Reusing an old wax ring.
• Overtightening the bolts.
• Installing on a cracked or loose flange.
• Reusing an old supply hose if it's worn.
• Forgetting to remove the rag from the drain before setting the toilet.

If your bathroom has an uneven tile floor, a flange that sits below the finished floor, or signs of water damage around the flange, those issues should be addressed before installing the new toilet to ensure a reliable seal.

If you'd like, tell me:

• What kind of flooring you have (tile, wood, vinyl)
• Whether you noticed any damage to the floor flange when removing the old one

I can give you extra tips for a secure fit!

If you'd like, let me know:

• Is your current floor a concrete slab or wood subfloor?
• Are you replacing an old-style 4-bolt or standard 2-bolt flange?

I can give you tips for any unique clearance or leveling issues.

1. Shut off and remove the old toilet

1. Turn off the water at the shutoff valve.
2. Flush the toilet and hold the handle down to empty the tank.
3. Sponge out remaining water from the tank and bowl.
4. Disconnect the supply line.
5. Remove the nuts from the two floor bolts.
6. Rock the toilet gently side-to-side to break the old wax seal, then lift it away. A helper is useful because toilets are awkward and heavy.The Home Depot
7. Stuff a rag into the drain temporarily to keep sewer gas out and prevent anything from falling down the pipe.

2. Inspect the flange

Scrape all of the old wax from the flange and the bottom of the toilet area.

The flange should be firmly attached to the floor and not cracked or badly deteriorated. If it's damaged, repair or replace it before installing the toilet. A loose or damaged flange can eventually cause leaks and floor damage.The Home Depot+1

If you discover rotted flooring, a broken drain pipe, or a flange that is glued/sealed to damaged piping, that's a good point to stop and get a plumber rather than forcing the repair.The Home Depot

3. Install the new seal

Put the new closet bolts into the flange slots with their threaded ends pointing upward.

Then install the new wax ring according to its instructions. It can generally either be placed on the flange or attached to the underside of the toilet bowl. A thicker seal may be necessary if the finished floor is unusually thick or the flange sits low.The Home Depot

Don't reuse the old wax ring.

4. Set the toilet bowl

This is the most important part.

1. Remove the rag from the drain.
2. Carefully lower the bowl straight down over the two bolts.
3. Make sure the bolts pass through the holes in the toilet base.
4. Once the bowl contacts the wax ring, press down firmly and evenly so the seal compresses.
5. Check that the toilet is square with the wall.

Try not to lift, twist, or rock the toilet after you've compressed the wax ring, because you can compromise the seal.The Home Depot

If the floor isn't perfectly flat, use toilet shims to eliminate rocking.

5. Tighten the bowl

Install the washers and nuts on the floor bolts.

Tighten them a little at a time, alternating sides, until the toilet is firmly seated and doesn't rock. Don't try to make the nuts extremely tight—porcelain can crack from excessive force.Eco Actions from The Home Depot+1

Trim the excess bolt length if necessary and install the decorative caps.

6. Attach the tank

If yours is a two-piece toilet:

1. Install the large rubber tank-to-bowl gasket.
2. Carefully set the tank onto the bowl.
3. Insert the tank bolts, washers, and nuts.
4. Tighten the bolts alternately until the tank is secure and properly positioned.

Again, don't overtighten. The goal is a secure connection, not maximum torque.

7. Connect the water

Connect the supply line to the toilet's fill valve, then slowly open the shutoff valve.

Let the tank fill and inspect:

• Supply-line connection
• Tank-to-bowl connection
• Around the toilet's base
• The shutoff valve

Flush several times and continue watching for leaks.The Home Depot

One important tip

Don't caulk around the toilet base until you've confirmed everything is leak-free and the toilet is stable. If you do caulk it, follow your local plumbing requirements and the toilet manufacturer's instructions; leave whatever drainage gap your code/manufacturer specifies so a concealed leak can be detected.

If you're replacing an existing toilet with the same type of toilet, this is mostly a straightforward mechanical job. If you're installing a toilet where one didn't previously exist, moving the drain, changing the flange location, or dealing with a damaged subfloor, the job becomes substantially more involved.