How to Replace a Toilet Bowl

There are many tasks in life that aren’t necessarily the most technically challenging, but we’d still rather leave it to a professional for… other reasons. For example, when you need a fuse board replacing, you call an electrician because you need someone with the appropriate skills and qualifications. When you need your garden re-turfing, there is no reason you can’t break out the shovel and dig it all up yourself, but you’ll probably call an expert because it’s hard work, and there are people who will happily do it for you for a fee.

Replacing a toilet bowl occupies something of a middle ground between these two examples. It is not the most technically challenging job (though it still requires at least some knowledge of plumbing), but most people would rather pay a professional to take care of it for them because, well, it’s a toilet. Let’s not beat around the bush; it’s a receptacle for human waste, and changing it involves getting your hands dirty… though hopefully not literally.

Still, just because most people would rather call a plumber doesn’t you mean there aren’t those of you out there who want to tackle this particular problem yourself, and there’s nothing wrong with that, but you need to know what you’re doing. You certainly don’t want to find out that your toilet isn’t installed properly when you come to use it for the first time.

In this post, we will walk you through the process of replacing your toilet bowl, including what you will need to carry out the task. It’s worth noting, however, that while plumbing is not necessarily as dangerous as gas or electric, it can still cause significant property damage when done incorrectly. And, with a toilet, there are also health and safety risks to consider. If you are not confident in your ability to carry out this task, you should definitely call a professional in to take care of it.

Bringing out the Tools

The exact tools you will need for any given toilet will vary a little depending on the type of toilet, but not by much. The following list of tools and items should be sufficient for the vast majority of toilet replacement jobs.

  • Screwdrivers
  • Adjustable wrenches
  • A pipe/plumber’s wrench
  • A bucket
  • Some rags or old towels
  • A box spanner
  • Rubber gloves and possibly a face mask
  • Caulking gun
  • Pipe cutter
  • Spirit level
  • Tape measure

If you are replacing your toilet bowl with a toilet that matches the original one—that is, one that will sit right over the existing fixtures and fasten into place, then that should be all the tools and materials you’ll need. If your toilet is a different design, you may also need to drill more holes to fix the toilet in place, so factor that in when getting your tools together.

There are also tools that you don’t necessarily need but that can make your life a little easier, such as a wet vacuum, and locking pliers.

How to Replace Toilet Bowl: A Step by Step Guide

Step #1 Choose (and buy) Your New Toilet

It should go without saying, but you don’t want to start any of this process until you have a new toilet ready and waiting to go. Even if you live in a house with several toilets and one being out of commission won’t be an inconvenience, it’s still best from a hygiene standpoint to not have an open toilet drain in your home for longer than you need to. Be sure to consider the location your new toilet will be going in before you buy, especially if it is something of a cramped space.

Step #2 Remove the Old Toilet

Before you do anything, you will need to turn the water off in your property. If you have a water cut-off for the specific room or region the toilet is in, you can use that, but most homeowners will need to turn the water off entirely. This is because the feed to the toilet’s water tank will need disconnecting. If you are lucky, the water feed may have been installed with a cut-off valve, in which case you can use that.

With the water off, flush your toilet. This will empty the cistern and, since the water is disconnected, it won’t be able to fill up. From there you can go ahead and disconnect the water feed.

Once the cistern is empty and disconnected from the water feed, you can remove it entirely. Note that this is only necessary for the standard toilet design where the cistern sits on top of the toilet bowl, behind the seat.

If your cistern is high up or set into the wall, you will probably not need to remove it, but you will still want to drain the tank before removing the toilet. 

Once the cistern is off, you can turn your attention to the toilet bowl.

The toilet should be fixed to the ground through two substantial bolts, which can be removed using a box spanner or a socket and ratchet. If the waste pipe comes off the back of the toilet, tilt the toilet backwards before lifting it free so that as much of the water in the bowl pours into the waste pipe. Either way, it is probably a good idea to put those rags or towels down to soak up any spillage.

Step #3 Prepare the Area for your New Toilet

The first thing you will want to do is clean up any silicon or caulk left over from the old toilet. This should have been applied around the base of the toilet where it meets the floor. You might also want to give the area a good mopping while it is clear.

Cut the caulk seal around the base of the bowl using a pocketknife.

Next up, replace the wax ring (where applicable), which will need a bit of industrious scraping off. The wax ring is the thing that stops toilet water from leaking out of the interface between the toilet and the waste pipe, so you’ll want to make sure this is done properly. If your toilet doesn’t have a wax ring, we would still recommend replacing the rubber equivalent. These materials degrade and perish over time and, for the small amount that it costs to buy something like that, it’s not worth not changing it while you have the toilet out of the way.

Don't press it down, but instead allow the weight of the bowl to compress the wax seal.

Finally, check that everything is fine with your toilet flange and the bolts that will be holding the new toilet in place.

Step #4 Fit the New Toilet

If your waste pipe is in the floor, you can simply lower your toilet into position over the waste pipe and the bolts. If your waste pipe comes through the wall behind the toilet, you will need to slide the toilet’s outlet into the waste pipe interface (which should be flexible) before you lower it onto the bolts.

Once your toilet is in place, you can tighten the bolts that hold it down. You want these bolts to be tight enough to hold the toilet firmly in place, but don’t go overboard because you can crack the base of your toilet if you tighten those bolts too much.

Step #5 Install Your Cistern

The process from here is more or less a reverse of step 2. If you are installing a new cistern with your new toilet, you may need to assemble the flushing mechanisms inside the cistern. For this you will need to consult the instructions that came with your specific toilet.

Do not over tighten the bolts or you could crack the tank.

Once you are ready, lower your cistern into place. Before you start fastening it to the toilet bowl, check that the points for mounting it to the wall line up, and if not, re-drill the wall for the new mounting points.

Finally, once you are sure everything is firmly attached, you can reconnect the water feed to your cistern. You may even want to pour a little water into the cistern first to make sure there are no leaks between the cistern and the toilet bowl.

Step #6 Turn the Water Back On

Once all that is done, the only left to do is to turn the water back on. If everything has gone to plan, your cistern should begin to fill up. Give the toilet a test flush once it is ready, because it’s much better to find out there is a problem with an unused toilet than one that has just been used.

Hire a Plumber

As you can see, this is not a light task. On the face of it, there is little in the way of highly technical skill required, but there are many points where things can go wrong, and when it comes to the health and hygiene of your home, it’s just not worth doing it wrong. If you’re at all unsure about your ability to carry this task out, you should hire a plumber to take care of it for you.

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