How to install a close-coupled toilet

Guide written by:

Jeremy, construction site supervisor, Cardiff

118 guides

While you will always have to install a toilet in a new building, it's also sometimes necessary to replace an old model. From connecting the flush system to fitting the toilet pan and seat, the job can be usually be done by any DIYer! Here's our guide to correctly installing a close-coupled toilet.

Important features

Preparation
Assembling the toilet
Fixing the toilet to the ground
Connecting to the waste and water supply
Sealing and finish

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Close-coupled toilets: easy installation

Whether you are looking to replace an old toilet or install brand new one, close-coupled toilets present the easiest and fastest solution. Most often purchased as a complete kit, these toilets are straightforward to assemble and connect.

Of course, you must already have a water inlet hose in place and this must be equipped with a shut-off valve. You will also need a PVC pan connector. Back-to-wall toilets are available in various heights and widths, and offer different volume capacities. They can be fitted with either a normal or water-saving flush system, and provide a range of design options.

Required skills

While installing a close-coupled toilet is relatively simple, it does require some know-how. You will have to know how to take accurate measurements, and be comfortable using a drill.

When it comes to assembling your toilet and connecting it to your water network, some previous plumbing experience will definitely come in handy.

You will also have to know how to use a sealant gun to create a silicone seal.

Completion time
About 2 hours
Number of people required
1 person

Steps to complete

1. Preparation;
2. Assembling the toilet;
3. Fixing the toilet to the floor;
4. Connecting the waste and water supply;
5. Sealing and finishing.

Tools and equipment

Close-coupled toilet (toilet pan, cistern, flush system and toilet seat);
PVC plumbing fixtures and fittings (pan connector, L-connector, adaptor, etc.);
A fixing kit for the ground (lag bolts, fixing plugs, screws, etc.);
PVC-based glue;
A roll of PTFE tape;
A silicone cartridge and sealant gun;
A tape measure;
A pencil or marker;
A drill and corresponding drill bits;
An electric screwdriver and corresponding screwdriver bits;
A set of screwdrivers;
A spirit level;
A set of open-ended spanners;
A hacksaw with a special plastic blade;
A box spanner or, failing that, multigrip pliers;

How to install a close-coupled toilet

1. Preparation

To start, you will have to set up for installation. This step consists of checking that the kit contains all the parts you need. The majority of closed-couple toilet kits are composed of:

A toilet pan;
A cistern;
A cistern lid;
A flush system;
A fixing kit for the cistern;
A fixing kit to connect the pan to the floor.

Please note that toilet seats are rarely provided with kits. Once you're sure that everything is in order, the second step will be to double check that the area is set up correctly for installation.

You will need to ensure that the intended location of the toilet is equipped with a PVC waste pipe and water inlet hose controlled by a shut-off valve.

2. Assembling the toilet

Installing the flush system

It's best to start by assembling the entire flush mechanism inside the tank. Instructions should be provided with the kit.

The key part of the system crosses the length of the cistern and is held up on both sides by rubber seals. To lock into place, simply tighten the nuts, being careful not to over-tighten to avoid damage (cracking the porcelain, breakage, etc.). At the same time, fix the flush buttons to the cistern lid.

Check that the flush system is correctly aligned by simply put the lid back on the cistern and pressing the flush control.

Fixing the cistern

Now that the cistern is equipped with the flush system, it must be installed over the toilet pan.

It will usually be fixed using screws mounted on washers. Position the screws in the cistern, pass them through to the toilet pan and tighten the nuts

Don't forget to seal the connection between the cistern and pan. Once again, be careful not to overturn the nuts to avoid cracking or breaking the porcelain.

3. Fixing the toilet to the floor

In order to work exactly where your close-coupled toilet will go, you will need to trial run its position with the location of the waste pipe in mind.

As the waste pipe will be connected to the toilet pan by a pan connector, you will have to take into account the length of the fitting before marking out your toilet's floor position.

Depending on what type of fixing plugs are provided with the kit, you will need to mark the position of the holes that will accommodate your fixing plugs, brackets or lag bolts.

Remove the toilet and drill holes to match the supplied fixings. Insert the fixing plugs or lag bolts, but do not tighten all the way – this will be done once the toilet has been connected to the waste pipe.

4. Connecting to the waste pipe and water supply

Assembling the waste connector

At this point in the process, you will have assembled the close-coupled toilet and pre-drilled holes in the ground for the required fixtures.

Before bolting it down definitively, you will need to make sure that the toilet is properly connected to the existing water network.

If your network is equipped with a flexible waste connector, the process will be very quick as you simply need to screw the connector into place. These connections are usually also fitted with seals.

If you have a rigid connector, start by placing your toilet back into position using your floor outline. Measure the exact length of the PVC pipe you require to make the connection. Depending on the position, you may need to install an L-connector.

Connect all the components and carry out a trial run. If all is well, fix everything into place by gluing one end of the pan connector to the waste pipe and the other to the toilet pan.

Once everything is assembled, fix the toilet pan to the ground making sure not to overtighten your screws.

Connecting the water supply

The water inlet hose must be equipped with a shut-off valve. Most shutoff valves and fill valve shanks come in standard 1/4 inch (12 x 17 mm) sizes. If this is the case, simply screw them into each other (and seal the connection with PTFE tape).

If your connections are different, you might need to use an adaptor to get them to the required size. Be sure to check that the system is watertight by turning on the water. The cisterm will slowly start to fill up. Once it's full you can test out the flush mechanism.

If there are no leaks between the water inlet hose, cistern, toilet pan or waste, then you have installed everything correctly and the system is watertight.

5. Sealing and finish

All that remains now is to apply silicone sealant around the base of the toilet pan. If you want to be able to use your newly installed back-to-wall toilet, you will also have to fit it with a toilet seat. The vast majority of toilet pans come with pre-drilled holes for fixing a standard toilet seat.

This may not always be the case so do refer to the assembly instructions if in doubt. More often than not, however, installing a toilet seat is as simple as threading the bolt through the holes in the porcelain and tightening the nuts underneath. As has been the case throughout the installation, this is another example of where over-tightening can crack the porcelain so be careful not to cause any damage.

The last step will simply consist of checking your toilet seat has the proper range of movement, then your close-coupled toilet will be ready for use!

More information

Whether you're designing or renovating a bathroom, check out our editors' advice with these related guides:

And to make sure you have the right tools, check out the following guides:

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Guide written by:

Jeremy, construction site supervisor, Cardiff 118 guides écrits

Electrician by trade, I first worked in industrial estates where I installed, wired and fixed a large number of electrical installations. After this, I managed a team of electricians for this type of work. 10 years or so ago, I turned to building and construction. From the modest family home, to gyms and theatres; I have been able to coordinate, audit and organise all sorts of construction sites.

for 4 years now, I am restaoring and bulding an extrension to a bungalow in the heart of the welsh countyside. My experience in manual work and my knowledge means I am proud to be of service. Terraces, interior design, roofing, plumbing, electricty, anything goes! We have, my wife, daughter and I, built almost everything we have from scratch! So to answer all of your questions, and to orientate and advise you on coosing your tools? Easy!