What you need to do before you start
Replacing a toilet is a project most people can do in two to four hours with basic tools. You will need to turn off the water supply, drain the old toilet, disconnect it from the floor and the water line, then install the new one in reverse order. The hardest part is usually breaking the old wax seal that sits between the toilet and the floor — it hardens over years and can stick tight.
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 bolts that hold the toilet to the floor. Standard rough-in is 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 either sit too far from the wall or too close, and you cannot fix that without moving the drain pipe.
Check whether your new toilet will fit in your space. Measure the width of your bathroom at the toilet location and the distance from the toilet to any door or wall. Most standard toilets are about 30 inches wide, but compact models are narrower. If space is tight, measure before you buy.
Key Takeaways
- Standard rough-in distance is 12 inches from the wall to the center of the floor bolts, so measure your old toilet before buying a new one.
- Turn off the water supply at the shutoff valve under the tank, flush to empty the bowl, and use a sponge or wet/dry vacuum to remove remaining water.
- The wax seal between the toilet and floor hardens over time and requires steady pressure or a wax seal removal tool to break free.
- New toilets come with a wax ring, bolts, and washers, but you may need to buy shims if your floor is not level.
- After installation, let the caulk cure for 24 hours before using the toilet, and check for leaks where the water line connects to the tank.
Shutting off the water and draining the tank
Locate the water shutoff valve under the toilet tank on the left side. Turn it clockwise until it stops — you should feel resistance, but do not force it. If the valve is stuck or will not turn, you may need to shut off the main water supply to your house instead. Once the valve is closed, flush the toilet to empty the tank and bowl.
Water will remain in the bowl even after flushing. Use a sponge to soak up the standing water and wring it into a bucket, or use a wet/dry vacuum to remove it. Do not skip this step — water left in the bowl will spill onto your floor when you disconnect the toilet. After the bowl is empty, use the sponge or vacuum on the tank as well.
Disconnecting the water line and removing the old toilet
The water line connects the shutoff valve to the bottom of the tank. It is usually a flexible hose with a nut on each end. Place a bucket under the connection at the tank, then use an adjustable wrench to turn the nut counterclockwise. The line may still have water in it, so the bucket will catch the drip. Once the nut is loose, unscrew it by hand and set the line aside.
The toilet is bolted to the floor through two bolts on either side of the base. These bolts go through the base of the toilet and into the floor. Pry off the plastic caps covering the bolts, then use an adjustable wrench or socket wrench to loosen the nuts. Once both nuts are loose, you can lift the toilet straight up. It will be heavy — usually 80 to 100 pounds — so get help or use your legs, not your back.
After you lift the toilet away, you will see the wax ring stuck to the floor. Scrape it off with a putty knife or old chisel. This is messy and takes patience. If the wax is very hard, a heat gun or hair dryer can soften it slightly. Once the wax is removed, cover the drain opening with a rag so you do not drop anything into it and so sewer gas does not come up into your bathroom.
Preparing the floor and installing the new wax ring
Inspect the floor where the toilet sat. If it is not level, you will need shims — thin plastic or wood wedges that slip under the toilet base to level it. You can buy shims at any hardware store. Check the floor with a level tool in both directions (front to back and side to side). If the floor slopes more than a quarter-inch over the footprint of the toilet, you will need shims.
Remove the rag from the drain opening. The new toilet comes with a wax ring in a cardboard sleeve. Press the wax ring firmly onto the bottom of the new toilet, centered over the drain hole. Some people prefer to place the wax ring on the floor instead, but placing it on the toilet is more reliable because it stays in place as you lower the toilet down.
If your floor needs shims, place them now in the spots where the toilet will rest. You can adjust them after the toilet is in place. Lower the new toilet straight down over the bolts, aligning the bolt holes in the base with the bolts sticking up from the floor. Press down firmly and evenly to compress the wax ring. Do not rock the toilet side to side — this breaks the seal.
Bolting the toilet to the floor
The new toilet comes with bolts, washers, and nuts. Slide a washer onto each bolt, then thread the nut onto the bolt by hand. Once both nuts are hand-tight, use an adjustable wrench to tighten them. Tighten a little on one side, then a little on the other, alternating back and forth. This keeps the toilet level as you tighten. Stop when you feel solid resistance — do not over-tighten, as this can crack the porcelain base.
If you used shims, you can leave them in place or remove them after tightening. Many plumbers leave them in place to avoid disturbing the wax seal. Once the bolts are tight, snap the plastic caps back over the nuts to hide them.
Reconnecting the water line and testing for leaks
Turn the shutoff valve counterclockwise to turn the water back on. Water will flow into the tank. While the tank is filling, check under the toilet for leaks where the water line connects. If water is dripping, turn the shutoff valve back off, place a bucket under the connection, and tighten the nut slightly with a wrench. Then turn the water back on and check again.
Let the tank fill completely, then flush the toilet and watch the bowl refill. Check again for leaks at the water line connection and under the base where the wax ring sits. A small amount of condensation on the outside of the tank is normal, but active dripping is not. If water is leaking from under the base, the wax seal did not set properly and you will need to remove and reinstall the toilet.
Finishing touches and caulking
Once the toilet is working and not leaking, you can caulk around the base. Use a caulk gun to apply a thin bead of silicone caulk around the base where it meets the floor. Caulk keeps water from getting under the toilet if the bowl overflows or if you splash water during cleaning. Smooth the caulk with a wet finger or caulk tool, then let it cure for 24 hours before using the toilet heavily.
Do not caulk all the way around the base — leave a small gap at the back or side so that if a leak develops under the toilet, you can see water pooling on the floor. This early warning gives you time to address the problem before water damages the subfloor.
Frequently Asked Questions
Do I need a plumber to replace a toilet?
No. Replacing a toilet is a straightforward project that does not require a license. If you are comfortable with basic tools and following steps in order, you can do it yourself. Hire a plumber only if the shutoff valve will not turn, if the old bolts will not come loose, or if you are not confident working with water connections.
What if the shutoff valve under the toilet is broken?
If the valve will not turn or leaks when you try to turn it, you will need to shut off the main water supply to your house instead. The main shutoff is usually in the basement, crawlspace, or outside near the meter. If you cannot find it or it will not turn, call a plumber. Do not force a stuck valve — you can break it and create a bigger problem.
Can I reuse the old wax ring?
No. Wax rings harden after a few years and lose their seal. Always use a new wax ring that comes with the new toilet. Reusing an old ring is the most common reason toilets leak from underneath after installation.
How long does it take to replace a toilet?
Most people finish in two to four hours. The longest part is usually scraping off the old wax ring. If the bolts are stuck or corroded, it can take longer. Plan for the full afternoon so you are not rushed.
What should I do if water leaks from under the toilet after installation?
Turn off the water, remove the toilet, and inspect the wax ring. If it is cracked or compressed unevenly, replace it with a new one. Reinstall the toilet using the same steps. Leaks from under the base almost always mean the wax seal failed, not that something else is wrong.