How to Install a Toilet

How to Install a Toilet: Guide and Pro Tips

So you bought a new toilet, and you’re ready to install it? In this guide, RAVE brings you all the information you’ll need, as well as helpful tips from real pros.

Or maybe a new toilet just isn’t in the budget right now. What might surprise you, though, is that your old toilet could actually be costing you more money than you think. That’s because many older toilet models waste a lot of water, driving up your monthly bill.

What’s more, toilets have come a long way in recent years, not only in terms of design but also concerning extra features in smart toilets, like no-touch flushing and soft-close seats. On top of that, a new toilet is simply a great way to freshen up the look of your bathroom.

The most expensive thing about installing a new toilet isn’t the toilet at all — it’s the labor. One way to fit a new toilet into your budget is to do the installation yourself. While that’s easier said than done, DIY toilet installation is possible.

RAVE Reviews knows there are lots of other toilet installation guides out there. So in addition to covering the steps required to install a toilet on your own and the tools required to get the job done, RAVE sought out advice from professional plumbers. 

We wanted to know all the little things they learned about installing toilets on the job — what to do, what to avoid, and how to prepare. The advice they shared was invaluable.

Table of Contents

Glossary of Terms for the Modern Toilet

In order for this guide to make sense, we should first cover what a parts make up a toilet. So that you’ll know which tools to use at different stages of installation or repair. And which parts to inspect if you notice problems. Despite the appearance of simplicity, there’s more parts in a toilet than you might imagine.

Also, understanding the various parts of a toilet and their technologies will help you to better evaluate which toilets offer the most value and if you can get away with simply replacing the faulty parts of your current toilet.

In reading through our guide, we recommend coming back to this glossary if you are confused by any of the steps of the installation process.

  • ADA Toilets — Models that meet the standards of the Americans with Disabilities Act
  • Backflush — A toilet with a waste valve in the wall behind it, instead of the floor below it.
  • Ballcock or Float Valve — A mechanism in the tank that refills the toilet tank once water has been flushed.
  • Bidet System — A spray system designed to clean the user instead of (or in addition to) toilet paper
  • Elongated Toilet — Refers to toilets with a longer seat that provide easier sitting for large users that take up a larger footprint of space in your bathroom (requires careful measuring).
  • Flapper — The rubber disc that holds water in the tank, and then is lifted to send water through the flush valve.
  • Floor Flange — A ring around the waste outlet or drain pipe, should be flush with the bathroom floor. The toilet is fastened to the floor flange.
  • Flush Valve — Located inside the tank, this valve shoots water through the bowl to remove waste.
  • GPF Rating — This rating refers to the gallons of water used per flush.
  • Inlet Spud — The connector between the flush valve and the incoming water supply. Usually located on the top of the toilet.
  • One Piece — Models of toilet design where both the tank and the toilet bowl are one solid piece, as opposed to two-piece models.
  • PSI — The pounds per square inch of the water supply being fed to the toilet.
  • Refill Tube — Incoming water supply tube that’s secured to the water tank by the inlet spud.
  • Shut Off Valve — A hand twisted knob, or screwdriver stop used to shut off water supply during installation or repair (so that you don’t have to turn off water to your entire house).
  • Trap — Fixture used to prevent backflow or sewer water, waste, and/or fumes.
  • Trap Seal — Minimal amount of tank water needed to prevent backflow through the trap.
  • Trip Lever — The lever that you use to start the flushing mechanism
  • Waste Outlet / Drain Pipe — The hole in the floor or wall which receives the toilets flushed water and waste.
  • Wax Ring — Secured between the floor flange and the toilet to create a seal and prevent leaks of fumes or wastewater.

The Tools Needed to Replace a Toilet

Now that you know the various parts of a toilet and its important terms, let’s talk a bit about the tools and supplies you’ll need to successfully install a toilet, all on your own.

  • Gloves — Preferably water proof gloves
  • Rag — not just any rag, but a rag that you won’t mind getting extra dirty
  • Plenty of towels and sponges
  • Drill — a handheld screwdriver also works
  • Pliers, or an adjustable wrench
  • Toilet shims
  • Caulk
  • Putty knife
  • Hacksaw

In addition, you’ll need a wax ring and a toilet flange repair ring — either metal or plastic will work. Just be sure to choose a flange repair ring that works with your existing flange. 

Something else to be aware of is that the wax rings may need to be extra thick, especially if you have thick tile. Wax rings are also some of the first parts to break down over time, so consider checking this first if you notice waters leaks around the base. Or if you smell the fumes of sewage.

We also recommend picking up a knee cushion, as kneeling on tile can be uncomfortable after an extended period of time. For a budget option, consider rolling up a towel to act as a buffer between your knees and the bathroom floor.

Now that your tools are in place, let’s go over how to prepare to replace a toilet. Turns out there’s a lot you can do to successfully install a new toilet before you even remove the old one.

Preparing to Replace a Toilet

Best Smart Toilets

First off, when preparing to replace a toilet, don’t forget to measure, says Stephany Smith, a member of the toilet fitters crew at Fantastic Handyman, providing over 40,000 property maintenance services each year. 

“Many homeowners decide to replace an old toilet without taking measurements,” Smith says, “just because it’s a daunting task.” To stay away from problems, and to cut down on measuring, your best bet is to opt for an “exact match” toilet model, Smith says. 

That’s because if the model of your choice doesn’t fit the current toilet configuration, you may find installing a new toilet much more complicated and time-consuming than it would be otherwise.

Here’s what to measure before even getting started on your toilet installation project:

The distance between the flange bolts and the wall behind your toilet — also known as “rough-in”

Smith says you’ll be safe if your toilet’s “rough-in” dimension is between 11-13 inches. But if you need a toilet model with an unusual rough-in size — 10 inches, 14 inches, or larger  — you could be in trouble. 

With too large of a rough-in size, your toilet may need to be special ordered; too small, and you’re faced with a whole other set of issues.

Opting for a toilet with a smaller rough-in than your current model will only lead to endless clogs, flush fails, and extra time and money spent changing the layout of your existing plumbing, Smith says.

Tank dimension

The next thing to measure is tank dimension. “Most of today’s toilet tanks are designed with smaller dimensions than their predecessors,” Smith says. Toilets with smaller tanks may potentially cost you thousands of dollars for wall renovations, since smaller tanks can expose stained or faded portions of the wall.

Bathroom space

Finally, simply measure your bathroom. The last thing you want is a toilet that inhibits free range of motion in your bathroom. 

“The general rule of thumb is the smaller the bathroom, the more compact the toilet,” Smith advises. “The best choice for a tiny bathroom space is a round-front bowl. Unlike the elongated models, round-front bowls are shorter and fit perfectly in almost every bathroom,” she says.

Now that you’ve done your measurements, here are a few other things to be aware of before picking out your new toilet:

The condition of the old toilet footprint

Tiles under your old toilet, like most things in life, are subject to wear and tear, Smith points out. 

“It also accumulates scum and sludge over time,” she continues. To avoid faded tiles or a visible outline from your old toilet footprint, buy a fixture with either a larger footprint or with a footprint that matches your current toilet. 

Furthermore, if you’re switching from a floor-mounted toilet to a wall-hung toilet, you could have a much bigger project on your hands than a simple toilet installation.

If this is the case, “you’re going to have to add some more framing into your wall,” says Aaron Barnett,  a qualified builder who has worked on many high-end builds. His site, Banging Toolbox, is dedicated to all things related to tools and DIY home improvement

“It’s also a bit more work to move the outlet pipe,” Barnett continues, “and you’re going to have to fix the hole in your floor in this scenario.” 

“It’s more cost-effective to replace same-for-same,” he says, “although some people prefer the more modern wall-hung design.”

Beware of the current waste outlet

To prevent sanitation issues, any plumbing system, including your toilet, has a built-in P or S trap, Smith notes, cautioning that if you don’t want to change the existing plumbing, you need to ensure that the new toilet meets your home-specific trapway. 

“Remember that dealing with different trapways requires both a plumber’s intervention and building permit,” she says.

Smith also recommends using high-quality brass bolts for fasteners. With solid brass bolts, you not only avoid the unsightly look of rust around your toilet, but you also preempt preventable delays during plumbing emergencies because of stuck or seized bolts.

Stuck or corroded bolts cause other issues as well. “Corroded connections don’t hold the toilet securely,” Smith explains,  “so sooner or later expect the water to seep out.”

Common Pitfalls of Toilet Installation

Here are a few other common mistakes beginners make when installing a new toilet, direct from a professional plumber:

  • Beware of electrical cables and water pipes

Before you drill into your floor or wall for any reason, always check for electrical cables and water pipes. “Professional plumbers know the dangers of hitting electrical cables or water pipes, so they always check for them in advance,” Smith says. Otherwise, life-threatening outcomes are possible, including flooding and electrocution.

  • Completely clean off the residue of the previous toilet

Don’t go halfway when cleaning off the residue from the previous toilet, Smith says. Otherwise, you’re in for a wobbly ride. Before setting your new toilet, she says, “measure the top of the flange. It should be no more than ¾ of an inch. Otherwise, the toilet may not sit evenly on the floor.

  • Don’t try it alone

Toilet bases are heavy and bulky. It’s challenging for one person to align them properly on the new bolts, so get help from a friend or a specialist to protect your back when lifting the heavy toilet and to properly secure the fixture without damaging the wax ring. 

“Incorrectly aligned flanges and seals will make your toilet prone to leaks,” Smith says.

  • Don’t over-tighten the bolts 

Next, over-tightening bolts will only result in shortening the life of the bolt or even a broken toilet, according to Smith. To reduce the chance of bolts loosening over time, she says, add rubber or plastic washers, with nuts over them. “The trick is to snug the parts by hand and then by using a wrench,” Smith says.

To check if the nuts are satisfactorily tightened, fill the tank with water and look for drips or leaks. If you notice a puddle of drops on the floor, it’s a sign that you can tighten the bolt a bit more. 

  • Use a level

It’s also very important to make sure your toilet tank is level before affixing it to the wall. Use a spirit level to do so, Smith says.  An unleveled cistern, she adds, will only cause excessive pressure on the one side and make the toilet less secure and prone to damage. 

  • Measure your water-supply pipe

Although connecting your water supply is as simple as connecting a water pipe with the cistern and tightening it with a wrench, a frequent mistake is buying a new water line without taking adequate measurements.  “You may think the one you already have is in good working order,” Smith says, but it may in fact be too short or too long for your new toilet. 

“Having an idea of the new water line size will save you a lot of frustration,” Smith adds.

  • Install a separate shut-off valve

Leaks, clogs, or other toilet malfunctions will occur in every home. To avoid major disruption, not only with your toilet but also with the water supply of your entire house, your best bet is to make sure there’s enough space to fit an individual toilet shut-off valve, Smith advises.

So far we’ve covered a few vitally important steps to take care of before you begin to install your new toilet, in addition to some common pitfalls to avoid along the way. We’ve also talked a bit about the tools you’ll need to get the job done quickly and efficiently.

Up next is a step-by-step guide to removing your toilet and installing a new one on your own. 


Many other toilet guides will walk you through the process of installing a toilet. What RAVE set out to do was find out all the things the professionals know that the average DIY home renovator only finds out through trial and error and a lot of frustration.

We asked professional plumbers for their input on the following:

  • The steps involved in removing an old toilet
  • How to install a new toilet
  • How to prepare for the process
  • What to do after you’re finished
  • Common pitfalls 

All this combined presents the most thorough and complete picture of the toilet installation process, proving that even you can install a toilet like a professional. So, let’s get started.

How to Remove the Old Toilet

Once you have your tools in place, your area measured, and your fasteners selected, it’s time to remove your old toilet. Before you begin, though, it’s important to have a plan for what you’ll do with the old toilet once it’s removed.

RAVE recommends contacting your local Habitat for Humanity ReStore to find the nearest toilet drop off in your area. Recycling or donating your toilet to a charity means it won’t simply end up in a landfill and can possibly go to a new home for someone in need.

1. With that taken care of, it’s time to remove your old toilet.

  • Start by turning off the water using the shut-off valve. The water shut-off valve is usually located on the wall or floor. 
  • Flush the toilet to drain the water that’s in the bowl. Stephany Smith from Fantastic Handyman says to flush the toilet up to five times to ensure your system is completely drained. 
  • Use a plunger to force out any remaining water.

2. The next step is to disconnect the supply line with an adjustable wrench.

  • For toilets where the tank is a separate piece from the bowl, remove the tank bolts from the bottom of the tank. The tank can then be separated from the bowl by simply lifting it off. 
  • Now, identify the toilet bolt caps usually located on the base. Remove the bolts holding the base of the toilet in place with a pair of pliers or an adjustable wrench.

3. What to do if the bolts won’t budge:

If the bolts seem stuck, perhaps due to corrosion, Smith says not to waste too much time attempting to loosen them with an adjustable wrench. Simply cut through them with your hacksaw instead. And if the toilet still seems stuck to the floor once the fasteners are removed or cut, the issue could be with the wax ring. 

“The wax ring seals the toilet bottom with the floor,” Smith says. “With the help of a utility knife, you can easily cut through the layer.” 

4. Remove the base of the toilet.

The base of the toilet can now be removed by pulling it straight up. Be sure to keep it as upright as possible. This will prevent any leftover water from spilling out. If some water does spill, simply wipe it up with those handy sponges or towels you have at the ready.

This may leave some residue behind. You can scrape off the adhesive with your putty knife — just be careful not to damage your floor. 

Mineral spirit is a handy assistant when you want to erase the residual and speed up the cleaning process,” Smith says. 

Another word of caution from Smith about this step of the process involves the odors that will be released once the old toilet is successfully removed. Allowing sewer gases into your home is highly unsanitary, she says.

“To prevent foul odors, you need to act swiftly,” Smith continues. Remove the wax from the seal, clean the sealing surface with a wire brush or scraping tool, and, finally, cover the soil pipe with a cloth. 

Sewer gases pose the risk of viral transmission,” Smith continues, “which is troublesome these days,” in light of the COVID-19 pandemic.

But with your old toilet out of the way, Aaron Barnett of Banging Toolbox says this is a good time to do some extra measuring, just to be sure. “This will give you the full ability to measure all the dimensions before ordering a new toilet,” he says.

Now that your old toilet is removed, it’s time to put your new toilet in its place.

How to Install a Toilet

Installing your toilet is a bit like removing your old one in reverse.

1. Check the flange.

The first step is to check your flange for cracks. 

(The flange is that piece that allows the toilet to connect to the floor and is under your wax ring. Don’t worry, we didn’t know what the flange was either when we first got started.)

If your flange is cracked, just use a flange repair ring. Be sure, however, to get one that is compatible with your existing floor flange. 

Pro tip: take a photo of your floor flange before heading out to the hardware store. If you’re unsure what you need, simply show that photo to someone in the plumbing department. 

(Plus, you can use that photo to humblebrag on Instagram. If a toilet installation occurs and it isn’t on social media, did it really happen?)

Here’s how to replace your flange if your old one is cracked.

  • Place the flange repair ring into the existing flange and secure it in place.
  • Next, position the new bolts that hold your toilet in place. Be sure to use the new bolts that came with your toilet.

2. Install the wax ring.

Now it’s time to install your new wax ring. There are two ways of doing this, and we’ll tell you which one we prefer.

  • The first approach is to place the wax ring on the floor and then position the toilet on top of it. We found this approach made it a bit difficult to position the wax ring in just the right spot.
  • Another way to install the wax ring is to first position the toilet bowl upside down — we learned the hard way that you’ll want to put something soft underneath it — and then attach the wax ring to the bottom of the bowl. This makes it much easier to get the wax ring positioned correctly!

Once that step is taken care of, it’s time to place your new toilet onto the flange. 

Here’s how:

Align the bolt holes with the bolts in the flange. Once it’s in place, set the seal by simply pressing down. It’s important at this step to not move, twist, or tilt the toilet too much, because that can cause the wax seal to break.

A broken wax seal leads to possible leaks, and that’s never a good thing.

3. Apply nuts and washers.

Now it’s time to place a washer and nut on each toilet bowl bolt. 

Tighten them but don’t over-tighten them, He-Man or She-Ra (we know you’ve been working out). Otherwise, you may crack the porcelain on your brand new toilet.

Next, you’re going to need that hacksaw again because it’s time to trim off the excess bolt, cutting them short enough so that the plastic bolt caps can snap snugly in place.

4. Reattach the water-supply line.

Congratulations! You’re almost there. The last step is to reattach the water-supply line

After reattaching the water supply line, test the toilet for leaks. The best way to do that is to slowly turn on the water valve, which will then fill the tank. 

Now, flush your toilet. Where you’ll want to pay extra attention is to the point at which the tank and bowl meet. You’ll also want to check where the toilet meets the floor. 

No leaks mean a job well done.

A word about different toilet models — depending on the model you choose, there may be extra steps involved in the installation process. In addition to our guide, be sure to check your toilet’s instructions for any extra steps.

Post Toilet Installation

Your toilet is now installed, but you’re not quite done.

You’ll also need to install the toilet seat as well as shim and caulk your toilet. 

Luckily, toilet seats are pretty easy to install, and, again, each one comes with instructions. Simply follow the instructions, and you should be good to go.

Shimming and caulking your toilet is also pretty easy:

1. Shimming your toilet

Shimming your toilet — or to put it another way, fixing it if it’s still unstable — is important. A correctly installed toilet shouldn’t rock back and forth at all. 

  • If your toilet is wobbly, use a plastic shim in any low spots until the issue is taken care of.
  • Keep that utility knife handy, because it’s now time to trim the shim so everything’s nice and flush with the base of your new toilet. 

2. Caulking your toilet

Now it’s time to caulk!

Although there are lots of different kinds of caulk out there to choose from, experts agree that silicone caulk is the best caulk to use around a toilet, even though it’s a bit more expensive.

Whatever caulk you choose, just make sure it’s clear.

Now that you’ve picked out your caulk, here’s what to do:

  • Apply an even layer, or bead, of caulk at the point where the base of the toilet meets the floor to create a waterproof seal.
  • Use your finger to smooth out the bead of caulk

One word of caution: all caulk goes on white, even the clear kind. So don’t worry — it will dry clear.

And you’re done!

There you have it. With this guide, you’ll be able to install a toilet like a professional (and maybe even without calling your dad for help). As you can see, with good preparation and a little hard work, it really is possible to install a toilet all on your own.