Weak toilet flush

[Stradlater]

Hi all, I have a push button toilet which flushes weakly. Sometimes it takes 2 flushes to get material down the pipe. The water currently rises to 21.4 cm in the tank.

Would anyone have a solution to this?

Thanks.

 

[oldbuffer]

1. Does the water rise to the line engraved on the back of the cistern? This will be a 6 litre fill if modern, 9 litre if old. If not, adjust float level until it does.
2. Does the water exit evenly (in terms of flow) around the rim of the pan? If not, suspect blockage / lime scale, and clean as appropriate.
3. Does the water flow freely through the plan to the soil pipe?