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How to...

install and repair
a toilet

A brief guide.
Skill rating: easy / intermediate

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This guide shows you how to carry out small, simple repairs to your toilet or, if it needs replacing, how to install a new one. These are some of the easiest plumbing jobs in the home and can probably be completed in a matter of minutes or up to a couple of hours to install a new toilet. If you’re in any doubt, get the help of a qualified plumber.

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Quick links

  1. Adjusting a poorly flushing toilet
  2. Clearing obstructions
  3. Repairing a toilet that won’t stop running
  1. If there’s water on the floor
  2. Replacing a toilet

1: Adjusting a poorly flushing toilet

CHECKING THE WATER LEVEL IN YOUR CISTERN

  • To do this, lift off the cistern cover to see if the water level is in line with the waterline mark (usually marked on the cistern itself or on the overflow tube - fig. 1).

ADJUSTING THE WATER LEVEL

  • The water level can be adjusted using the slide device secured by a small locking bolt on the float arm (fig. 1 and 2). If a small adjustment doesn’t work you will have to replace the flush valve.
  • If the float arm does not have a slide device, adjust it using the screw at the point where the arm float connects to the intake valve. Adjust the screw anticlockwise to increase the water level or clockwise to decrease the water in the cistern. Once you are happy with the water level, lock the screw into position with the nut provided.

REPLACING THE FLOAT

  • If the float has water in it, it will need replacing. Unscrew the float from the float arm and screw a new one in its place. Make sure that the water level in the cistern is not more than 12mm below the overflow pipe on the cistern or the integral siphon overflow.

OTHER PROBLEMS

  • If your toilet bowl doesn’t fully empty during a flush it isn’t necessarily a problem. Some low-consumption toilets don’t completely empty.
  • Fully open the main water supply valve to ensure that there’s enough water pressure and volume - this is a knob/tap you twist found on the wall near your toilet (fig. 1).
  • Lastly, there may be a slight obstruction in the trapway, which is the curved passageway extending from the opening in the bottom of the bowl to the waste pipe - to remove this, see below.

    helpful hint...

    Always wear rubber gloves when working on a used WC bowl and wash hands thoroughly afterwards.

fig. 1 (fig. 1) This is how the toilet is split into its component parts.

fig. 2 (fig. 2) Adjust the water level in your cistern by sliding the device up or down.

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2: Clearing obstructions

  • A small obstruction can cause slow flushing, leave a dirty bowl and cause frequent clogging.
  • Small obstructions can usually be cleared by several hard pushes with a toilet plunger to the bottom of the toilet bowl.
  • You can use a drain blaster to remove any larger obstructions within the pipes.
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Tools for the job...

Stock Check

Don't forget you can stock check these items online

Pipe and wire detector

Pipe and wire detector

Set of screwdrivers

Set of screwdrivers

Power drill

Power drill

Push fit connector

Push fit
connector

Adjustable wrench

Adjustable wrench

Float

Float

WD40

WD40

Toilet Seat

Toilet seat

Adjustable spanner

Adjustable spanner

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3: Repairing a toilet that won’t stop running

  • Start by jiggling the toilet handle. If the running stops, you need to either adjust the lift chain (fig. 1) attachment or the handle. Check that the siphon linkage is not sticking.

CHECKING THE BALL FLOAT

  • If that doesn't work, remove the cistern cover and see if the float is touching the side of the cistern. If it is, clean the float or if possible adjust its position away from the edge of the cistern.
  • Also, check that the float ball is maintaining the water at the correct level in the cistern - see ‘Adjusting a poorly flushing toilet’.
  • If the float ball has water in it, replace it - see above.

    • helpful hint...

    Never flush a blocked toilet since there is a chance this will cause the toilet to overflow and become a health hazard.

    REPLACING THE FLAPPER VALVE SEAT

  • If the flapper valve seat (fig. 1) is pitted or cracked, the whole flapper valve will need replacing.
  • You can buy kits for this but installing them usually involve detaching the cistern from the bowl.

REPLACING THE BALLCOCK ASSEMBLY

  • If the toilet still runs, it may be easiest to replace the entire ballcock assembly. You can buy this already assembled so you just need to install it. Follow the manufacturer's instructions.
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4: If there’s water on the floor

  • Check all the connections for leaks i.e. cistern bolts (used to attach the cistern to the wall and to the bowl) and the ballcock mounting nut (used to attach the main water supply to the cistern) - you may need to replace the washers.
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5: Replacing a toilet

This is a general guide – always follow any manufacturer’s instructions that come with your new toilet unit.

PUTTING TOGETHER THE CISTERN ASSEMBLY

  • Start by using the manufacturer’s instructions to assemble the toilet’s flush valve mechanism and insert it into your cistern, pushing the bottom threaded section through the hole in its base (fig. 3).
  • Make sure the rubber washer is on the flush valve mechanism in the cistern, then screw on the back nut securely, but don’t overtighten it.
  • Insert the push-button assembly through the hole in the top of the cistern, and fit the nut (fig. 4).
  • Fit the intake valve assembly into the cistern (fig. 1), making sure the rubber washer is in place, then lock it into position with the nut supplied. Tighten it by hand plus a half turn with an adjustable spanner.

CONNECTING THE CISTERN TO THE TOILET PAN

  • Put the large rubber gasket onto the flush entrance of the toilet pan (fig. 5).
  • Insert the long fixing bolts through the holes in the bottom of the cistern using the rubber seals and large metal washers supplied.
  • Lift the cistern onto the toilet pan with the connecting bolts going through the holes. The threaded section of the flush mechanism goes through the rubber gasket on the entrance of the pan (fig. 6).
  • Put washers on the connecting bolts and secure with wing nuts but don’t overtighten them.

SECURING THE PAN TO THE FLOOR AND TESTING FOR LEAKS

  • Check that there are no pipes or cables under the fixing points on the floor and position the toilet where required.
  • Slide the pan outlet into the flexible connector attached to the waste pipe.
  • Mark and drill pilot holes in the floor for the fixing points.
  • Push the plastic protective inserts through the holes in the base of the pan and screw it to the floor.
  • The cistern may also have fixing holes in the back. If so, fix it to the wall, remembering to add rubber washers before tightening the nuts.
  • Connect the supply pipe for the cold water feed using a push-fit tap connector and test for leaks.

FITTING THE TOILET SEAT

  • Fit the hinge to the seat following the manufacturer’s instructions.
  • Attach the seat to the toilet pan by securing it through the holes at the back using the nuts, bolts and washers supplied.
  • You’ll be able to adjust the bolts so the seat sits in the correct position and the lid/seat stay upright when required.
  • Check all bolts and connections have been tightened correctly.

    helpful hint...

    If you are replacing an old toilet seat and find the nuts and bolts are rusted, try using a little WD40 to ease them.

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fig. 3 (fig. 3) Push the threaded section of the flush valve through the cistern with the washer on the inside.

fig. 4 (fig. 4) Insert the push-button lever through the hole in the lid of the cistern and screw the nut tight.

fig. 5 (fig. 5) Place the large rubber gasket over the entrance to the toilet pan.

fig.6 (fig. 6) Lift the cistern onto the toilet pan and tighten up the wing nuts ensuring there are washers between the nuts and the pan.

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