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Toilet Leaks

Your toilet can be a bit of a drip. Some older cisterns flush 10 or 11 litres a time, perhaps 20 times a day. That's 200 litres or more a day, when they are working properly. Leaking cisterns, either from the overflow or into the toilet bowl, add insult to injury. 

Let us help you save money - If you have a single flush toilet we may be able to assist with a gizmo so you can part flush.

Toilet Leak

Here's how to fix the problem

If you are losing water through the overflow at the top of the cistern, then the shut-off valve which stops the flow of water into the cistern is not working properly.

In an older cistern, fixing it may simply be a matter of bending the brass arm which runs from the valve to the float. Bend it downwards and it will shut off earlier. Just remember to make sure it lets enough water into the cistern to give a full flush.

If the ball-cock itself is the problem, here is what to do.

Toilet Leak - Ballcock


If you have an older style cistern like the one in the diagram above:

  • turn off the tap on the pipe leading into the cistern
  • flush the cistern to empty it
  • remove the split pin (a) which holds the float in place and remove the float arm (b)
  • unscrew the cap (c) on the end of the valve and remove the washer plunger (d)
  • you may need to turn the water on briefly to make the washer plunger appear. Turn off the tap to stop the water pressure before you remove the valve, otherwise water will go everywhere! 
  • unscrew the washer-retaining ring (e) and replace the washer (f) 
  • return the washer plunger to the body with the hole facing downwards
  • reinsert the float arm and the split pin and screw on the end cap
  • turn on the water again and test the flush

    You can check whether you are losing water through the outlet (or flapper) valve at the bottom of the cistern by putting a few drops of food colouring in the cistern. Don't flush the toilet for about ten minutes and then check the water in the bowl. If it is coloured, you have a leak.

Modern Toilet Cistern


If you have a modern cistern like the one in diagram two:

  • turn off the tap on the pipe leading into the cistern
  • flush the cistern to empty it
  • unscrew the large nut on the end of ball float arm (a)
  • unscrew the washer retaining ring (b) and replace the washer (c)
  • reassemble the float arm assembly ensuring the guide tab lines up with slot at the bottom. Screw the large ring finger tight
  • turn on the water and test the filling of the cistern.

Free Waterline Service provided by Tauranga City Council.

Last Reviewed: 29/06/2016