How to Fit a Toilet

modern close coupled toilet side view

Close coupled toilets are straightforward to install and available in a wide range of designs, which makes them a popular option.

If you have DIY experience, then why not follow this step-by-step guide on how to fit a toilet? We’ve even include a handy video for further assistance and to make the installation process easier.

If your toilet leaks, is noisy and uses more water than what’s necessary, then it’s definitely time to replace it with a water-saving dual flush model. This will not only save you money in the long term, but you can save money by learning how to a fit toilet yourself.

Fitting a new toilet will instantly update the look of your bathroom or cloakroom suite, and with so many designs to choose from you’ll have no problem finding a style you’ll really like.

The toilet accounts for a third of all the water you use in your home, and an old model can use a staggering 10-13 litres of water per flush.

Dual flush toilets can use as little as 4 litres per flush. So, if you’re on a water meter, you’ll be saving money from the first time you flush your new toilet.

When buying a new toilet, check that it has an internal overflow feature. This feature means that if the fill valve develops a fault whereby it won’t stop filling the cistern, the extra water will go straight into the pan and drain away down the waste pipe.

Watch: how to fit a toilet

What is a closed coupled toilet?

The most common type, a close coupled toilet is where the cistern is fitted directly to the pan (closely coupled together – hence the name).

They are available in modern and traditional designs to suit any bathroom. For small bathrooms opt for a short projection toilet to maximise space – this is where the pan has a shorter depth than standard. Comfort height toilets are higher than standard, making them a great option for those who are less mobile or elderly.

If you can connect your toilet to an existing branch of the soil pipe, it’s not too difficult to replace your old toilet. If you want to fit a new toilet in another area of your home, then you will need to call out a professional plumber to connect into the main soil pipe.

Installing a toilet in a new en-suite can cause problems as you will need to reroute the waste. A standard waste pipe measures 100mm in diameter, and when a house is built it is straightforward to route this large bore pipe from the toilet to the drain, but once the internal walls have gone up, routing this pipe to a new bathroom is tricky.

You can get around this issue by fitting a macerator on the back of the toilet – this pumps the waste away in a 22mm diameter pipe. Small pipework is easier to box in or run between floorboard joists.

Since there are electrical connections involved, and the area you are fitting it in is restricted under Part P of the Building Regulations, it means you will need to hire a qualified electrician. Macerators can cost £200, and an electrician will charge approximately £50.

Important notes

  • Before starting any work, unpack your new toilet straight after delivery, and check for any damage or faults. It’s better to find any damage now, rather than during installation.
  • If you’re easily able to isolate the water supply, and the waste and supply pipes do not need major alterations, fitting a new toilet is pretty straightforward.
  • The waste and supply pipes will need to be adjusted if you are changing the floor height in your bathroom. A small difference can be overcome by using an offset pan connector and a flexible pipe connector for the cold water supply. Larger differences require advanced plumbing skills.
  • Bed the toilet pan on silicone sealant if the floor is uneven. Small wooden wedges can be used to level the pan – ensure they are bedded in sealant to distribute the weight evenly.
  • If the waste pipe goes down through the floor, a right angled pan connector is required.
  • If you are fitting a high level or low level toilet, the cistern will be higher up on the wall – ensure there’s strong fixing points to support the weight. If the wall is hollow, the fixings must go into wooden studs.
  • If you are altering your bathroom, check with a qualified electrician to see if the bonding and earthing requirements need to be improved.
White close coupled toilet

Fitting a toilet – The order of work

If you are removing an old toilet, then follow these steps.

Step 1. Removing the old toilet

If you’re replacing your old toilet, then follow these steps to remove it.

Step 2. Turn off the water supply

Turn off the water supply at the shut-off valve and flush the toilet to remove as much water from the cistern as possible.

Step 3. Remove water from the bowl

Use a cup to remove the water from the toilet bowl.

Step 4. Unscrew the retaining screws

Unscrew the retaining screws at the base of the bowl, and undo the screws inside the cistern that secure it to the wall.

Step 5. Ease the toilet away from the wall

Now you can ease the toilet away from the wall and allow the waste pipe to disengage with the pan connector.

How to fit a toilet

Tools required to fit a toilet:

  • Safety glasses
  • Screwdrivers
  • Cable, pipe and stud detector
  • Adjustable spanner
  • Drill/driver and bits
  • Water pump pliers
  • Carpenter’s awl
  • Spirit level
  • Cartridge gun
  • Wall plugs
  • Silicone sealant
  • Screws
  • Pencil

Step 1. Fitting the new toilet

When assembling the toilet, the main work is assembling the cistern, so lay all the parts out in front of you to check you have everything.

Step 2. Assemble the inner part of the cistern

Follow the manufacturer’s guide to assemble the inner part of the cistern. This can vary from toilet to toilet depending on the type of flush valve.

Step 3. Tighten all parts

Ensure that all parts are tightened, but be careful not to overtighten. It’s a good idea to hand tighten where possible, and if using pliers, do so gently.

Step 4. Thread on the washers and bolts

The cistern will have bolts that connect it to the toilet bowl. Thread on the washers and bolts in the correct order.

Step 5. Lower the cistern in place

Ensure the large close-couple washer is positioned correctly on top of the pan and carefully lower the cistern in place.

Step 6. Insert the pan connector

Insert the pan connector into the waste pipe – make sure it’s a snug fit.

Step 7. Align the pipes

Position the toilet next to the waste pipe and check the pipes are aligned. Most toilets are a standard height. If the pipes don’t align then you may need an offset pan connector.

Step 8. Push the toilet into position

Push the toilet into position allowing the waste to connect with the pan connector. The toilet needs to fit right into the connector collar.

Step 9. Check the cistern is level

Use a spirit level to check the cistern is level. Mark off the fixing holes through the back of the cistern.

Step 10. Check the toilet pan is level

Check the toilet pan is level with a spirit level. Mark off the fixing holes in the base of the pan.

Step 11. Mark around the edge of the pan

Use a pencil to mark around the edge of the toilet pan so you have the exact position of the base when it comes to the final fitting.

Step 12. Drill the fixing holes

Move the toilet away from the wall and drill the fixing holes for the cistern through the marks you’ve made on the wall. Insert suitable wall plugs.

Step 13. Drill pilot holes

Next, you’ll need to drill pilot holes for the pan through the marks you’ve made. Insert suitable wall plugs according to the floor surface. No plugs are required for wooden floors.

Step 14. Apply silicone sealant

Apply silicone sealant around the inner edge of the marked pencil line, where the toilet pan will be positioned.

Step 15. Screw the cistern in place

Position the toilet carefully onto the sealant and screw the cistern into position. Use the washers, do not overtighten.

Step 16. Fix the pan to the floor

Fix the pan to the floor by inserting screws at the base of the toilet. Use all the washers taking care to not overtighten.

Step 17. Connect the cold water supply

Connect the cold water supply. You may need to use a flexible connector depending on the position of the new inlet pipe on the cistern.

Step 18. Check for leaks

Switch the water supply on at the isolation valve. Check for leaks along all piping joints and the pan connector.

Step 19. Fit the toilet seat

Fit the toilet seat by inserting the bolts through the pan and adding a washer and nut. Adjust as required to fit the toilet pan shape.

Step 20. Apply a final bead of sealant

Apply a final bead of sealant around the base of the toilet pan and smooth off with a damp sponge.

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