What to do when your cistern runneth over…

There’s water 
everywhere. What now?

Lift the cistern lid to see where the water level is in relation to the integrated overflow (an open-ended pipe that’s connected to the flushing mechanism). Hold the float arm as close as possible to the float mechanism to keep it steady, and adjust the water level by bending the float arm down. Using a pair of pliers will give you a slight advantage. The water level should be set 25mm below the integrated overflow level or at the level mark that’s usually etched inside the cistern. Check the level 30 minutes later to make sure the adjustment is right.

What if it’s still running?

The fault is likely with either the inlet valve or the flush mechanism. Flush the toilet and lift the inlet float manually. If the water stops flowing then the flushing mechanism is faulty.

How do I replace the flushing mechanism?

Remove the arm that connects the handle to the flush mechanism. The latest models are usually fitted with a bayonet connection so with a quarter-twist and a lift they’ll come out. Take it to a plumbing store. Very often it’s the rubber that needs replacing.

How do I replace the inlet valve?

A side-entry inlet valve can be easily replaced
by loosening the nut at the base of its arm that holds the float. Remove the arm and take it to a shop for a replacement.

When should I call in the pros?

If your toilet is an old model the cistern might need to be removed. This is not a DIY option. Also, replacing bottom-entry inlet valves are more complicated than side-entry inlet valves, unless you are comfortable with a pair of grips.

Sources: Kieron Alston of Alston Plumbing Services and Darren Bosman of Clyde Bosman Plumbing