How to repair an overflowing cistern

An overflowing cistern is usually caused by an old cistern flapper or by an overused seal between the cistern and the flapper. You can determine the real problem behind the overflow by checking the water level in the cistern.

If the water level is below the flapper, then you'll need to replace the seal between the cistern and that flapper. However, if the water level is right at the flapper, the problem lies behind the flapper so you'll need to replace it:

Level of difficulty

Level 2: Intermediate

What you need

• Wrench
• Screwdriver
• Nuts
• Bolts
• Screws
• Flapper
• Seal

The steps to follow

1. Turn off the shut-off valve. It's usually located on the left side of the cistern.
2. Remove the cistern cover.
3. Flush the toilet to empty the cistern. You can also manually empty the tank by pulling the chain that's attached to the flapper.
4. To disconnect the water supply line, turn the nuts clockwise with a wrench.
5. Unscrew the bolts located at the bottom of the tank and at the back of the bowl.
6. Remove the cistern from the bowl.

I. Replacing the flapper:
i. Unscrew the nut holding the flapper.
ii. Lift it out and dispose.
iii. Install a new flapper.

II.Replacing the seal:
i. To replace the seal, unscrew the nut between the base of the cistern and the flapper.
ii. Pull off the old seal and replace it with a new seal.

7. Screw the bolts and secure the cistern back on the wall and attach it to the bowl.
8. Turn on the shut-off valve and flush to see if it is working properly.