What you need to do before you start
Replacing a toilet is a project most homeowners can do in two to three hours with basic tools and no plumbing experience. The work is straightforward: you drain the old toilet, unbolt it from the floor, disconnect the water supply, lift it away, and install a new one in reverse order. The hardest part is usually breaking the old wax seal that sits between the toilet and the drain pipe—not because it is difficult, but because it is messy and smells bad.
Before you buy a new toilet, measure the rough-in distance. This is the distance from the wall behind the toilet to the center of the bolt holes where the toilet bolts to the floor. Most toilets have a 12-inch rough-in, 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 flat or will sit too far from the wall. Measure twice, then buy the toilet that matches your measurement.
Turn off the water supply valve, which is usually on the wall or floor behind the toilet. If you cannot find it or it does not work, turn off the main water valve for your house. Flush the toilet to empty the tank and bowl, then use a sponge or towel to soak up any remaining water in the bowl.
Key Takeaways
- Measure the rough-in distance (wall to bolt hole center) before buying a new toilet, because installing the wrong size will leave gaps or push the toilet too far from the wall.
- The old wax seal between the toilet and drain pipe must be scraped away completely, or the new toilet will rock and leak.
- Bolts on the floor can be stuck or corroded; if they will not turn, explore penetrating oil and wait 15 minutes, or cut them with a hacksaw or reciprocating saw.
- The new toilet must sit level on the floor, or water will pool inside the bowl and the seal will fail; use shims under the base if the floor is uneven.
Disconnect the water supply and remove the old toilet
Close the water supply valve by turning it clockwise until it stops. Disconnect the water line from the bottom of the tank by turning the nut counterclockwise by hand or with an adjustable wrench. Have a bucket or towel ready—there will be a small amount of water in the line.
Locate the two bolts that hold the toilet to the floor. They are usually covered by plastic caps on either side of the base. Pry off the caps with a flathead screwdriver. If the bolts are corroded or stuck, spray them with penetrating oil (like WD-40 or Liquid Wrench) and wait 15 minutes. Try turning them counterclockwise with an adjustable wrench or socket wrench. If they still will not budge, use a hacksaw or reciprocating saw to cut through the bolt shaft just above the nut, then remove the nut.
Once the bolts are loose or removed, rock the toilet gently side to side to break the seal between the base and the wax ring. Lift the toilet straight up and set it on its side on a tarp or in a bathtub—it will be heavy (usually 80 to 100 pounds) and water will drip from the trap. Stuff a rag into the drain opening to block sewer gases and prevent debris from falling in.
Clean the flange and prepare the floor
The flange is the ring bolted to the floor around the drain opening. Use a putty knife or paint scraper to remove all the old wax seal from the flange and the floor around it. Scrape until the surface is clean and smooth. If wax is stubborn, heat it with a heat gun or hair dryer on high to soften it, then scrape again. Wipe the flange with a dry cloth.
Inspect the flange for cracks or damage. If it is cracked or broken, it must be replaced before you install the new toilet—a damaged flange will not hold the wax seal and the toilet will leak. If the flange is in good condition, check that the floor is level using a 2-foot level. If the floor slopes or dips, you will need shims to level the new toilet base.
If the bolts came out of the flange, insert new ones now. Most flanges have slots that hold the bolts in place. Slide the bolts into the slots so they stand upright and parallel to each other, about 6 inches apart on either side of the drain opening.
Install the wax ring and set the new toilet
A wax ring is a ring of wax that creates a watertight seal between the toilet base and the flange. Most wax rings come with a plastic or rubber horn that points downward into the drain. Press the wax ring firmly onto the flange, centering it over the drain opening. The horn should point straight down into the flange opening. If the horn is removable, you can leave it on or remove it—either way works, but leaving it on is slightly easier for beginners.
Carefully lower the new toilet over the bolts and onto the wax ring. Align the bolt holes in the toilet base with the bolts sticking up from the flange. Lower the toilet slowly and press down firmly with your weight to compress the wax ring. The toilet should sit flat on the floor. If it rocks or feels uneven, lift it up, check for debris under the base, and try again.
If the floor is uneven and the toilet rocks, remove it and place plastic shims under the base where it is high. Shims are thin wedges sold at hardware stores in packs. Slide them under the base until the toilet sits level, then lower the toilet back onto the wax ring and press down firmly.
Bolt the toilet to the floor
Slide a washer and nut onto each bolt. Tighten the nuts by hand first, then use an adjustable wrench or socket wrench to tighten them further. Tighten a little bit on one side, then a little bit on the other side, alternating back and forth. Do not over-tighten—the bolts should be snug, but over-tightening can crack the porcelain base. Stop when you feel firm resistance; you should not be able to move the toilet by hand, but you should not need to strain to turn the wrench.
Once both bolts are tight, use a hacksaw or reciprocating saw to cut off the excess bolt shaft above the nut, leaving about 1/4 inch. This prevents the bolt from catching on clothing or causing injury. Snap the plastic caps back onto the bolts to cover them.
Reconnect the water supply and test for leaks
Reconnect the water line to the fill valve at the bottom of the tank. Hand-tighten the nut, then use an adjustable wrench to tighten it another half turn. Do not over-tighten—the connection is fragile and over-tightening can crack the fitting.
Turn the water supply valve back on by turning it counterclockwise. Water will flow into the tank. Let the tank fill completely, then flush the toilet. Watch for leaks at the water line connection and at the base of the toilet where it meets the floor. If water drips from the water line connection, turn off the water, tighten the nut another quarter turn, and try again. If water leaks from under the base, the wax seal did not seat properly—you will need to remove the toilet and reinstall it.
Flush the toilet two or three more times and watch the base and water line for leaks. If everything is dry after 10 minutes, the installation is complete. If you see water pooling inside the bowl after flushing, the toilet may be rocking on an uneven floor. Remove the toilet, add shims, and reinstall it.
When to call a plumber
Call a plumber if the flange is cracked or broken, because a damaged flange cannot hold a wax seal and must be replaced by someone who can access the drain pipe from below. Call a plumber if the bolts are seized and cannot be cut, or if the floor is so uneven that shims do not level the toilet. Call a plumber if water leaks from under the base after you have reinstalled the toilet twice, because this usually means the flange is damaged or the drain pipe is not level.
If you are uncomfortable working with the water supply line or do not have the right tools to tighten the connection, a plumber can finish the job in 15 minutes. There is no shame in stopping halfway through and calling for help—it is better than damaging the new toilet or creating a leak.
Frequently Asked Questions
Can I reuse the old wax ring if I have to remove the toilet again?
No. Once a wax ring is compressed, it loses its seal. Always use a new wax ring every time you install or reinstall a toilet. Wax rings cost $3 to $8 and are sold at any hardware store.
What if the new toilet keeps rocking after I install it?
The floor is uneven or there is debris under the base. Remove the toilet, clean the floor thoroughly, and check it with a level. Add plastic shims under the base where the floor is low, then reinstall the toilet. It should sit flat and not move when you push on it.
Do I need to caulk around the base of the toilet?
Caulking is optional. Some people caulk to prevent water from splashing under the base during cleaning, but it also makes it harder to remove the toilet later. If you do caulk, use silicone caulk and leave a small gap at the back so water can escape if the seal fails.
How long does a wax ring last?
A wax ring typically lasts as long as the toilet—15 to 30 years. If the toilet leaks from the base, the wax ring has failed and the toilet must be removed and reinstalled with a new ring.
What tools do I actually need to replace a toilet?
You need an adjustable wrench, a flathead screwdriver, a putty knife, a 2-foot level, and a hacksaw or reciprocating saw. A socket wrench set makes the job easier but is not required. Have a bucket, towels, and a tarp ready for water and mess.