If your bathroom throne has seen more leaks than a government memo, replacing it might just restore your royal dignity.
Whether it’s leaks, stains, bad flushes — or that ancient green color from the 1970s — the message is clear: your toilet is past its prime.
Installing a new toilet solves all those issues but also gives you quieter flushes, better water use, and a fresh look that can make your bathroom feel cleaner.
In this guide, we’ll go over:
- How to prepare a wax seal the right way (without leaks)
- Tips on picking the correct height of the toilet flange
- Testing the tank and toilet for leaks
- And more…
Let’s get started!
Key Considerations Before Replacing Your Toilet
Before starting a toilet installation, gather all the necessary tools and supplies to make the job go smoothly.
Also read our guide on toilet clearance and spacing codes to be sure it’s the proper distance from walls and other fixtures.
Tools And Supplies Needed
Here are a few key items:
- Gloves and Eye Protection – to keep your hands and eyes safe from dirty water, wax, and dried feces on the toilet flange.
- Adjustable wrench – for loosening and tightening the water supply line and closet bolts.
- Putty knife – for scraping off old wax and residue from the flange.
- Wax ring or rubber/synthetic seal – creates a watertight seal between the toilet and flange.
- New closet bolts and nuts – secures the toilet base to the floor.
- Sponge or wet-dry vacuum (optional) – helps remove standing water from the tank and bowl.
- Hacksaw or reciprocating saw (optional) – to cut off excess closet bolts so decorative caps can fit over them.
- Level (optional) – ensures the toilet sits evenly and doesn’t rock.
- Grout and caulk (optional) – grout gives some rigidity to the install and caulking provides a nice finish. I recommend leaving a small gap in the back to know if there’s a leak.
Permit May Be Required
In many areas, replacing an existing toilet is considered minor maintenance and does not require a plumbing permit, as long as you’re not moving the plumbing or drain lines.
However, local codes vary, and certain cities or counties (like parts of California, Massachusetts, and Illinois) have stricter plumbing codes. Check with your local permitting department.
Measuring For New Toilet
It’s important to verify that the new toilet fits your bathroom, lines up with the plumbing, and avoids awkward clearance issues. Check out our guide on toilet clearance and spacing codes for more information.
- Measure the Rough-In: Distance from the finished wall to the center of the flange bolts (commonly 12”, 10”, or 14”) makes sure the new toilet fits properly.
- Check Bowl Shape and Size: Choose round (16–17” front-to-back) or elongated (18–19”) depending on your space and preference.
- Consider Height: Standard toilets are ~15”; comfort/ADA-height models are 17–19” for easier use.
#1: Turn Off Water And Drain Toilet
The first step is always to shut off water to the toilet. Locate the shutoff valve behind the toilet and turn it fully clockwise until it stops (may be 1/4 turn or a couple full rotations).
If you suspect that the valve may leak due to age or rust, shut off the water to the entire home to be safe.
Drain Remaining Water
Remove as much water as possible from the toilet. When you lift up and move the toilet, contaminated water may spill onto the floor.
After removing water from the bowl/tank, there will still be some water in the internal P-trap of the toilet.
You have a few options to drain water from the tank/bowl and internal P-trap:
- Do A Hard Flush: hold down the flush handle for several seconds to maximize the drainage of tank and bowl.
- Use Sponge Or Cup: soak or scoop out any remaining water from the tank and bowl.
- Wet-Dry Vacuum: to quickly suck out leftover water from the bowl and P-trap.
- Bucket of Water: to pour water rapidly into the bowl to force most of the remaining water through the internal P-trap using a vacuum effect. This trick also works when your home’s water supply is shut off — see our guide on how to flush a toilet when the water is off for the step-by-step method.
- Add Liquilock: Liquilock or similar products turn the remaining water into a gel for spill-free removal.
- Old Rag or Plastic Cup: stuff a cloth or plastic cup into the drain opening to block odors and prevent tools or debris from falling in.
4 Steps To Shutting Off And Draining Water
- Locate Shutoff Valve: The valve is typically behind the toilet and near the wall. Rotate the valve clockwise until it stops. Angle stop valves only require a quarter turn.
- Flush Toilet: Flush the toilet and hold the handle down to empty as much water as possible from the tank and bowl.
- Remaining Tank Water: Use a sponge, rag, cup, or wet-dry vac to remove leftover water from the tank.
- Water Inside P-Trap: Quickly pour a bucket of water into the bowl to create a vacuum effect of the internal P-trap.
#2. Disconnect Water Line
Before removing the toilet, you’ll need to disconnect the flexible water line. The water supply line connects to the fill valve assembly directly underneath the toilet.
It’s a good idea to have an old rag ready or bucket to catch any water that spills out.
Use an adjustable wrench or channel-lock pliers to turn the nut counterclockwise to disconnect it. I recommend using a wrench if available since the grooves on channel-lock pliers can damage the nut’s finish.
If your flexible supply line is corroded or old, this is a great time to replace it. I like stainless steel braided supply hoses which are more resistant to leaks than the common black rubber type which is known to rupture.
4 Steps To Disconnecting Water Supply Line
- Prepare For Water: Place a towel or small bucket under the hose connection to catch drips.
- Loosen the Coupling Nut: Use your hand or an adjustable wrench to loosen the nut at tank connection. Gently pull the line free.
- Catch Water: Expect a small amount of water to drain and keep the towel or bucket handy.
- Inspect and Replace if Needed: Replace old or corroded lines with a braided stainless-steel hose for reliability.
#3. Remove Old Toilet
After disconnecting the supply line, pop off any plastic caps over the closet bolts and remove the nut/washer on the bolt.
For stubborn nuts, cut them off with a hacksaw or reciprocating saw, though you’ll need replacement closet bolts. The metal is typically soft and not too hard to cut.
I recommend placing a plastic sheet or drop cloth to protect the floor when you put down the toilet.
Break The Wax Seal
It’s best to gently rock the toilet back and forth to break the wax seal so you can remove the toilet. You may need a helper to lift up the toilet from the floor.
The main hazard when removing the toilet is water spillage from water in the bowl or P-trap. If you put the toilet immediately in a trash bag, it will contain any possible leaks when moving it out of the bathroom.
There is also the risk of dropping the toilet on the floor and damaging tile.
Disposing Old Toilet
When it comes to disposing of your old toilet, you have a few options. Many municipalities accept toilets at local recycling centers or landfills.
You may be able to put it on the curb or do a bulk pickup request from your local trash service.
5 Steps To Removing Old Toilet
- Remove Bolt Covers: Flip up or pry off any plastic caps covering the floor bolts.
- Unscrew Floor Bolts: Use a wrench to remove the nuts holding the toilet to the flange. If the bolts are stuck and rusted, apply penetrating oil first. You can use a hacksaw or reciprocating saw as a last resort.
- Break the Wax Seal: Gently rock the toilet side to side and front to back to loosen the wax seal from the flange.
- Lift the Toilet: Carefully lift the toilet straight up; it’s heavy, so get a helper if needed.
- Set Toilet Aside: Place the toilet on an old towel, drop cloth, or cardboard to protect the floor from damage or water leaks. Ideally, put the toilet into a large trash bag to contain leaks.
#4. Inspect Subfloor For Damage
It’s crucial to check the subfloor for any water damage. You can use a screwdriver (or other tool) to probe the surrounding wood for any softness.
If the floor moves when you step on it, you likely need to replace some of the subfloor.
Depending on the floor damage:
- Cut out all soft or discolored material: Remove any rotted subfloor until only clean, solid wood remains.
- Use proper replacement materials: Replace with moisture-resistant plywood or OSB like AdvanTech that matches the thickness.
- Reinforce the flange area: Add blocking or sister joists under the new subfloor to give solid support for the toilet and prevent future movement or rocking.
#5. Prepare Flange
A properly prepared flange is essential to prevent a loose toilet (rocking), leaks, and water damage. When a toilet causes floor damage, it’s usually due to a poorly installed wax seal and/or flange.
Removing Wax
The first step is to scrape off the old wax seal and cleaning it, a putty knife works great.
I strongly advise wearing gloves and eyeglasses. The flange and wax ring may be contaminated with human feces, especially if the wax ring and flange have a darkened look. You don’t want dirty pieces flinging into your eyes!
It’s a good idea to put a plastic cup or rag into the drain hole to prevent falling debris and to keep out sewer gas. Just be careful it doesn’t fall in and clog your drain.
Damaged Or Cracked Flange
It’s important to inspect the flange to make sure it’s solidly connected to the subfloor/joists and that it doesn’t move.
There are numerous products on the market to deal with a broken flange. Below are a few options on how to handle it:
- Flange Repair Rings: Reinforces a cracked or broken flange by securing a metal or PVC ring over the existing one.
- Flange Repair Kits: Includes replacement bolts and spacers to rebuild missing or damaged sections without removing the old flange.
- Replace Entire Flange: Cut or unbolt the old flange from the drain pipe and install a new one if it’s severely corroded or warped. (If your drain system uses a cast iron flange, replacing it is more complicated than with PVC or ABS. It’s best to have a plumber handle it.)
- Flange Extenders/Spacers: Raises the flange height to match the finished floor when it’s set too low.
Flange Height
A big mistake of homeowners is using a toilet flange that is below the floor. The flange needs to be at minimum flush with the FINISHED floor or 1/4-inch above it.
If you’re installing new tile, you’ll need to estimate the height — ideally installing the new tile floor first — and raise the flange if necessary. There are flange extenders (spacers) that you can buy to raise the height.
Install Closet Bolts
With a properly installed flange (and height), you’ll need to install the closet bolts and keep them raised.
Simply insert the closet bolts into the key-shaped opening, and slide them into place to line up with the toilet holes. The bolts need to sit in the flange with the threaded side pointing up.
If your flange doesn’t come with plastic retainers/washers to keep the bolts upright, apply a dab of plumber’s putty or caulking to keep them in place.
The bolts should be placed on each side of the flange to line up perfectly with the holes in the toilet.
Do A Dry Fit First
Ideally, do a practice dry fit with the toilet prior to installing the wax seal. You only have one chance to correctly squish the wax seal. The toilet needs to sit level onto the flange, otherwise, the wax seal won’t squish evenly — causing leaks.
7 Steps To Prepare The Flange
- Remove Old Wax: Scrape off all old wax residue with a putty knife until the flange surface is clean.
- Clear Debris: Wipe away dust, dirt, or corrosion with a rag or mild cleaner.
- Inspect Flange: Check for cracks, rust, or damage; replace if it’s broken or unstable.
- Check Level: Use a small level to make sure the flange sits flat and even with the floor surface.
- Assess Height: The top of the flange should sit about ¼ inch above the finished floor; if it’s too low, use an extender ring.
- Secure Bolts: Make sure the flange is firmly screwed to the subfloor.
- Dry Fit Test: Place the toilet base over the flange to confirm proper bolt alignment and height before adding the wax ring.
#6: Install Wax Seal and Lower Toilet
If the flange is level with the floor, I recommend using an extra thick or jumbo wax seal for better leak protection. When the flange is 1/4-inch above the floor, use the standard size for a good fit.
The best wax seals include a black plastic insert (horn) that gives structure to the wax and helps channel water flow.
Most plumbers recommend avoiding stacking two wax rings. This is a usually a bad practice that causes leaks because the two seals don’t properly bond together.
You may want to use a rubber or synthetic seal if you don’t want to deal with wax. Rubber seals tend to work better in cold environments.
Position Toilet And Seal It
You have only one chance to install the wax seal correctly. The wax seal needs to squish evenly over the flange or it will cause leaking. And don’t forget to remove the rag or plastic cup you put in the drain hole to stop sewer gas and debris.
You may need a helper for this step since you need to slowly put down the toilet. The toilet should go evenly over the wax seal.
The closet bolts should already be positioned upright and aligned with the toilet’s mounting holes.
Test Movement
After you press the wax seal, gently move the toilet side to side to see if it rocks.
If the toilet moves, it likely means that the wax seal didn’t compress properly and it may need to be re-done with a new wax seal. However, if the rocking is due to an uneven floor, you can install some wood shims underneath the base.
Tighten Bolts
Once the toilet is positioned, place the washers over the closet bolts and hand-tighten the nuts to secure it in place. Tighten the nuts evenly on both sides to keep the toilet level.
Use an adjustable wrench to make each nut snug, do NOT overtighten the bolts which may crack the porcelain — just use moderate force.
After tightening the nuts, you may have to trim off the bolt ends with a hacksaw if they’re too long for the decorative caps. The bolt metal is soft so it isn’t too hard to cut and snap them off with a hacksaw or reciprocating saw.
6 Steps To Install Wax Seal and Toilet
- Warm the Wax Ring: Let it sit at room temperature so it’s soft and pliable.
- Place Wax Ring and Align Toilet: Center the wax ring on the flange. Lift the toilet and line up the closet bolts with the toilet mounting holes.
- Lower Carefully: Set the toilet straight down onto the flange, keeping it level as you lower.
- Seat the Wax: Press down firmly or gently rock the toilet side to side to compress the wax evenly.
- Check Stability: The toilet should rest flat and not wobble; if it does, use shims before tightening bolts.
- Tighten Bolts: Add washers and nuts, tightening them evenly until snug—but don’t overtighten.
#7. Reconnect Water Line and Test For Leaks
After setting the toilet onto the wax seal, reconnect the water supply line to the fill valve, and turn on the water.
Immediately check for any leaks at the toilet or wall connection. Make sure to flush the toilet a few times to see if you have any leaks.
If you hear strange gurgles, hisses, or phantom refills after the flush, check out our guide on sounds your toilet makes and how to fix it to pinpoint the cause.
Check the base of the toilet for any water seepage as well as under the tank, especially near the bolt connections of tank to bowl.
Perform a Dye Test
A simple dye test can alert you to leaks between the tank and the bowl.
Place several drops of food dye into the tank to see if there’s water transfer without flushing.
After about 15-30 minutes, check the toilet bowl to see if the color has changed. If you notice dye in the bowl, you may need to adjust or replace the flapper or flush valve seal.
Option To Grout/Caulk Base
Once the toilet is securely set and confirmed leak-free, complete the installation by applying grout or caulk around the base for a clean, finished look.
Toilet manufacturers typically recommend leaving a gap at the back of toilet to spot future leaks easily.
I prefer grouting first because it can provide extra stability, especially if the floor is slightly uneven. The grout fills gaps and helps the toilet sit more firmly, reducing rocking.
Once the grout has set, apply a thin bead of caulk around the edges for a clean finish.
7 Steps To Reconnecting Water and Leak Testing
- Fill Tank: Turn on the water and let the tank fill completely.
- Inspect Connections: Check the supply line, shutoff valve, tank bolts, and base for water.
- Flush Toilet: Watch around the base for any seepage or movement.
- Check Floor Area: Look for moisture forming at the toilet’s base or nearby grout lines.
- Feel for Dampness: Run your hand around fittings and the floor edge to detect hidden leaks.
- Do a Dye Test: Add a few drops of food coloring to the tank—if color appears in the bowl after 10–15 minutes without flushing, the flapper or valve is leaking.
- Recheck Later: Inspect again after a few hours or the next day to catch any slow leaks.
Final Thoughts
Replacing an old toilet might seem like a hassle, but it’s one of those upgrades that can make a bathroom shine.
A solid installation prevents leaks, and gives smoother flushes. Once it’s done right, you’ll wonder why you didn’t tackle it sooner.
I hope you enjoyed this guide by TimberSill. Leave a comment below or ask me a question!