What You Need to Do Before You Start
Replacing a toilet is a project you can do yourself in two to four hours with basic tools and no plumbing experience. The work breaks into three phases: removing the old toilet, preparing the floor, and installing the new one. You will need to turn off the water supply, drain the tank and bowl, unbolt the old toilet from the floor, and then reverse the process with the new unit.
Before you buy a new toilet, measure the rough-in distance—the space from the wall behind the toilet to the center of the bolts that hold it down. Standard rough-ins are 12 inches, but some older homes have 10-inch or 14-inch rough-ins. If you install a toilet with the wrong rough-in, it will not sit flush against the wall. Check your current toilet by measuring from the finished wall (not the baseboard) to the center of one of the floor bolts.
Gather your tools and materials before you begin: an adjustable wrench, a putty knife, a sponge, a bucket, a new wax ring (comes with most new toilets), new bolts and washers if your old ones are corroded, and a new toilet seat if one is not included. Wear old clothes and have towels ready—there will be water on the floor.
Key Takeaways
- Measure the rough-in distance (wall to bolt center) before buying a new toilet, because installing the wrong size will leave a gap at the wall.
- Turn off the water supply at the shutoff valve under the tank, flush to empty the bowl, and use a sponge to remove standing water before unbolting.
- The wax ring seals the toilet to the floor drain and must be replaced every time you remove a toilet, even if it looks intact.
- Tighten the floor bolts hand-tight first, then use a wrench to snug them evenly—over-tightening cracks the porcelain and under-tightening causes leaks.
Turn Off the Water and Empty the Tank
Locate the shutoff valve on the water supply line under the tank, usually on the left side. Turn it clockwise until it stops—you should feel resistance but do not force it. Flush the toilet once; the tank will not refill because the water is now shut off. If water continues to run into the bowl, the shutoff valve is faulty and you may need to turn off the main water supply to your house instead.
Use a sponge to soak up any water remaining in the tank and bowl. Wring the sponge into a bucket. This step prevents water from spilling across your floor when you disconnect the supply line and tip the toilet. If there is still standing water in the bowl after you have sponged it, use a wet/dry shop vacuum or a turkey baster to remove it.
Disconnect the Water Supply and Remove the Old Toilet
Use an adjustable wrench to loosen the nut on the water supply line where it connects to the bottom of the tank. Turn it counterclockwise until the line comes free. If the nut is stuck, spray it with penetrating oil and wait five minutes before trying again. Have a bucket or towel ready—a small amount of water may drip out.
Look under the toilet base for two bolts, one on each side, that go through the floor flange and into the base of the toilet. These are usually covered by plastic caps that snap off. Use your wrench to loosen both bolts by turning them counterclockwise. Once they are loose enough to turn by hand, remove them completely and set them aside. If the bolts are corroded or stripped, you will need new ones when you install the new toilet.
Rock the toilet gently side to side to break the seal of the old wax ring. Straddle the bowl, grip both sides of the rim, and lift straight up. The toilet is heavy—usually 80 to 100 pounds—so bend your knees and lift with your legs, not your back. Set the old toilet on its side on a tarp or in a bathtub so you do not damage the floor. Do not drop it; cracked porcelain is sharp and the toilet will be harder to move.
Clean the Floor Flange and Install the Wax Ring
The floor flange is the metal or plastic ring bolted to the floor where the toilet was sitting. Use a putty knife to scrape away the old wax ring completely—it will be dark, sticky, and crumbly. Scrape until you see bare metal or plastic. Wipe the flange clean with a rag. If the flange is cracked or broken, it must be replaced before the new toilet can seal properly; this is a more involved repair that may require a plumber.
Check that the bolts in the flange are upright and not bent. If they are bent, remove them and install new ones in the same holes. The bolts should stick straight up from the flange, parallel to each other, about 5 to 6 inches apart.
Press a new wax ring onto the bottom of the new toilet, centered over the outlet hole. The wax ring is soft and moldable—push it firmly so it sticks. Some wax rings come with a plastic or cardboard collar; if yours does, keep the collar on. Do not remove the wax ring until you are ready to set the toilet in place; it will fall off if you carry the toilet upside down.
Set the New Toilet and Bolt It Down
With help if possible, lift the new toilet and position it over the floor flange so the bolts pass through the holes in the base. Lower the toilet straight down onto the wax ring. The weight of the toilet will compress the wax and create a seal. Do not rock the toilet side to side once it is down; rocking breaks the wax seal.
Slide a washer and then a bolt nut onto each bolt. Tighten both bolts by hand first, turning them clockwise until they are snug but not tight. Then use your wrench to tighten each bolt a quarter turn at a time, alternating between the left and right side. This keeps pressure even and prevents the toilet from tilting. Stop when you feel firm resistance—the bolts should be tight enough that the toilet does not rock, but not so tight that you are straining. Over-tightening cracks the porcelain base. Once the bolts are tight, snap the plastic caps back over them.
If the toilet rocks slightly after bolting, loosen both bolts and check that the wax ring is seated evenly. Tighten again, alternating sides. A small rock is normal and usually settles after a few flushes as the wax compresses fully.
Reconnect the Water Supply and Test for Leaks
Reconnect the water supply line to the fill valve at the bottom of the tank. Hand-tighten the nut first, then use your wrench to snug it another quarter turn. Do not over-tighten; the connection is brass and can crack. Turn the shutoff valve counterclockwise to restore water pressure. The tank will fill and the bowl will refill after the first flush.
Flush the toilet three times and watch for leaks. Check under the tank where the water line connects, around the base where the toilet meets the floor, and inside the tank for any drips from the fill valve. A small amount of condensation on the outside of the tank is normal. If you see water pooling under the toilet base, the wax ring is not sealed properly and the toilet will need to be removed and reset with a new wax ring.
Install the toilet seat by sliding the bolts through the holes on the back of the seat and threading the nuts underneath. Tighten by hand until snug; do not use a wrench on the seat bolts, as this can crack the porcelain.
Common Mistakes and How to Avoid Them
The most common error is installing a toilet with the wrong rough-in size. Measure twice before you buy. A 12-inch rough-in is standard in most homes built after 1950, but do not assume. If you install a 10-inch toilet in a 12-inch space, there will be a visible gap between the tank and the wall, and the toilet will not look right.
Reusing an old wax ring is the second most common mistake. Even if the old ring looks intact, it has lost its seal and will leak. A new wax ring costs three to five dollars and takes thirty seconds to install. It is not worth the cost of water damage to your floor.
Over-tightening the floor bolts is the third mistake. Many people assume tighter is better, but porcelain cracks easily. Tighten until the toilet stops rocking, then stop. If the toilet still rocks after both bolts are snug, the wax ring is not seated evenly—remove the toilet and try again rather than cranking harder.
Forgetting to turn off the water supply before you start will result in water spraying everywhere when you disconnect the supply line. Always locate and test the shutoff valve before you begin any work.
Frequently Asked Questions
Can I install a new toilet if my floor is not level?
A slightly unlevel floor is normal and the wax ring will compress to seal. If the floor slopes more than a quarter inch over the toilet's footprint, the toilet will rock and the seal will fail. Shim the base with plastic shims under the bolts until the toilet is level, then tighten the bolts. Do not use metal shims; they can rust and stain the floor.
What if the old bolts are stuck and will not turn?
Spray the bolts with penetrating oil (such as WD-40 or Liquid Wrench) and wait 15 to 30 minutes. Spray again and try turning with your wrench. If they still will not budge, you may need to cut them with a hacksaw or reciprocating saw. New bolts are inexpensive and come with most new toilets, so do not spend an hour fighting old ones.
How do I know if the wax ring sealed properly?
Flush the toilet and watch the base for water pooling or seeping. Check again after an hour and before you go to bed that first night. If no water appears, the seal is good. If water pools under the toilet, you will need to remove it and reset it with a new wax ring.
Do I need a plumber to replace a toilet?
No. The job requires only basic tools and no special skills. If you are uncomfortable working with water lines or lifting heavy objects, a plumber can do it in under an hour, but the task is well within reach for most homeowners.
Can I replace a toilet without turning off the water?
You can remove the old toilet without shutting off the water, but you will have a much bigger mess. Water will run into the bowl and tank as you work, and disconnecting the supply line will spray water across your floor. Always turn off the water first.