What you need to do before you start
Replacing a toilet is a project most homeowners can handle without calling a plumber, though it takes patience and attention to detail rather than special skill. The job involves shutting off the water, draining the old toilet, unbolting it from the floor, and installing a new one with fresh wax and bolts. You will need basic tools you likely already own, and the whole process usually takes two to three hours for someone doing it for the first time.
Before you buy a new toilet, measure the rough-in distance — the distance from the wall behind the toilet to the center of the bolts that hold it to the floor. Standard rough-in is 12 inches, but some older homes have 10-inch or 14-inch rough-ins. If you buy the wrong size, it will not fit. You can find this measurement by removing the old toilet's tank lid and measuring from the wall to the center of one of the bolts on either side.
You will also need to decide between a standard two-piece toilet (tank and bowl separate) and a one-piece model. Two-piece toilets are cheaper and easier to move through doorways. One-piece toilets look sleeker and have fewer crevices to clean, but they cost more and are heavier. Both work the same way once installed.
Key Takeaways
- Measure your rough-in distance (wall to bolt center) before buying a new toilet, as standard is 12 inches but some homes have 10 or 14-inch rough-ins.
- Turn off the water at the shutoff valve under the tank, flush to empty the bowl, and use a sponge or wet/dry vacuum to remove remaining water before unbolting the old toilet.
- Remove the old wax ring from the floor flange and install a new one before setting the new toilet, as a bad seal causes leaks into the subfloor.
- Tighten the bolts evenly in a cross pattern (one side, then opposite side) to avoid cracking the porcelain, and do not over-tighten — hand-tight plus a quarter turn is usually enough.
- After installation, let the caulk cure for 24 hours before using the toilet, and check for leaks at the base and tank connection over the first week.
Shutting off the water and draining the toilet
Locate the shutoff valve on the water supply line under the tank — it looks like a small knob or lever on the copper or plastic line coming from the wall. Turn it clockwise (or pull the lever toward the wall if it is a lever-type valve) until it stops. Then flush the toilet once to empty the tank and bowl.
Water will remain in the bowl even after flushing. Use a sponge to soak it up and wring it into a bucket, or use a wet/dry vacuum to suction it out. This step is messy if you skip it — you will spill water all over the floor when you tip the toilet to remove it. Spend the two minutes now and save yourself the cleanup.
Unbolting and removing the old toilet
The toilet is held to the floor by two bolts, one on each side, that go through the base of the bowl and into the floor flange (a metal or plastic ring set into the floor). These bolts are usually covered by plastic caps that snap off or screw off. Pry them off with a flathead screwdriver.
Use a wrench or socket to loosen the nuts on both bolts. If they are stuck or corroded, spray them with penetrating oil (like WD-40) and wait 10 minutes before trying again. Once both nuts are loose, rock the toilet gently side to side to break the seal between the wax ring and the flange, then lift the toilet straight up and set it on its side on a towel or cardboard (the bowl will still have a little water in it).
Scrape off the old wax ring from the floor flange using a putty knife or old chisel. Get it as clean as you can — dried wax left behind will prevent a good seal with the new ring. You may also need to remove the old bolts from the flange and replace them with new ones, as they are often corroded or damaged. New bolts usually come with the new toilet or can be bought separately for a few dollars.
Installing the new wax ring and setting the toilet
A wax ring is a ring of soft wax that seals the gap between the toilet base and the floor flange, preventing water from leaking into the subfloor. It comes with most new toilets. If it did not, buy one at any hardware store for $5 to $10 — do not skip this step, as a missing or bad seal will rot your subfloor over time.
Press the wax ring firmly onto the flange, centered over the hole. It should stick to the flange on its own. If you are installing a two-piece toilet, set the bowl first (the tank comes later). Align the bolt holes in the base with the bolts sticking up from the flange, then lower the bowl straight down onto the wax ring. Do not slide it or twist it — set it straight down. You should feel slight resistance as the wax compresses.
Hand-tighten the nuts on both bolts, then use a wrench to tighten them in a cross pattern: tighten one side a quarter turn, then the opposite side a quarter turn, then back to the first side. This keeps pressure even and prevents cracking the porcelain. Stop when the toilet feels snug — do not over-tighten. If you crack the bowl, you will have to start over with a new toilet.
Connecting the tank (for two-piece models)
If you bought a two-piece toilet, the tank comes separate. Set it on the bowl, aligning the bolts on the tank with the holes on the back of the bowl. Slide rubber washers and bolts through the tank and into the bowl, then hand-tighten the nuts underneath. Tighten in a cross pattern again — one side a quarter turn, then the opposite side — until snug. Again, do not over-tighten.
Connect the water supply line to the inlet on the bottom of the tank. If the old line is still good (no cracks, no kinks), you can reuse it. If it looks worn, buy a new one — they cost $10 to $20 and take 30 seconds to install. Hand-tighten the connection, then use an adjustable wrench to tighten it a quarter turn more.
Filling the tank and checking for leaks
Turn the shutoff valve back on by turning it counterclockwise (or pulling the lever away from the wall). Water will flow into the tank. Let it fill completely, then flush once to make sure the fill valve and flush mechanism work. The tank should refill and the water should stop when it reaches the fill line.
Check the base of the toilet where it meets the floor — there should be no water pooling or dripping. Check the connection between the tank and bowl (if you installed a two-piece model) — it should also be dry. If you see water, turn off the shutoff valve and check your connections. A leak at the tank-to-bowl connection usually means the bolts need tightening; a leak at the base usually means the wax ring did not seal properly, which means you will need to remove the toilet and try again with a new wax ring.
If everything is dry, caulk around the base of the toilet where it meets the floor using a silicone caulk and a caulk gun. This is optional but recommended — it keeps water from getting under the toilet if you spill or if the bathroom floods. Let the caulk cure for 24 hours before using the toilet heavily.
When to call a professional
Call a plumber if the shutoff valve will not turn off — this means you may have a problem with the water supply line that needs professional attention. Also call if you remove the old toilet and find the floor flange is cracked, broken, or sitting below the level of the floor. A damaged flange will not seal properly and will need to be replaced or repaired before you can install a new toilet.
If you tighten the bolts and the toilet still rocks or feels unstable, the floor may be uneven. A plumber can shim the toilet (place thin metal or plastic shims under the base) to level it before final tightening. If you crack the new bowl while installing it, stop and call a plumber — they can help you remove it safely and start fresh.
Frequently Asked Questions
Can I reuse the old wax ring?
No. Wax rings are single-use — once they are compressed and removed, they lose their seal. A reused wax ring will leak. Always install a new one.
What if the bolts are stuck and will not turn?
Spray them with penetrating oil and wait 10 to 15 minutes. If they still will not budge, use a hacksaw or reciprocating saw to cut through the bolt above the nut, then remove the nut. You will replace the bolts anyway when you install the new toilet.
How do I know if my toilet is leaking at the base?
Place a piece of toilet paper or a paper towel on the floor around the base and wait 30 minutes. If it gets wet, you have a leak. Check again after 24 hours to make sure the caulk has not just been wet from installation.
Do I need to caulk around the toilet?
Caulking is not required for the toilet to work, but it prevents water from seeping under the base if you spill or if the bathroom floods. If you do caulk, use silicone caulk, not acrylic — silicone resists water better and lasts longer.
What if water is leaking from the tank connection?
Turn off the water and tighten the bolts connecting the tank to the bowl using a wrench. Tighten a quarter turn at a time in a cross pattern. If it still leaks after tightening, the rubber gasket between the tank and bowl may be damaged — you will need to remove the tank and replace the gasket.