However as this water would be foul water e.g. water mixed with waste it wouldn’t be clean like fresh water and it would also stink! As we have discussed, the most common cause of close coupled cistern leaks is that cistern isn’t sitting at 90° on top of the toilet pan. If the cistern is leaning over, even a little, one side of the doughnut lifts and, with a lot of water pressure, the leak is exposed. With the water turned off you can now safely disconnect the supply pipe. Before you do so though, place some old towels under the area surrounding the pipe and an old tray of some type. There will spillage so you will need to catch it all. With the wall fixings removed the final job before removing the cistern is to loosen and remove the through bolts holding the cistern to the pan. Using a spanner if there are nuts present or your fingers if there are wingnuts, unscrew each nut and then carefully lift the cistern free of the toilet pan.

This is especially important if the leak is with a newly installed close coupled toilet! The through bolts, as stated above, secure the cistern to the toilet by running down through holes in the base of the cistern and top of the toilet. Then the real trouble began. Given its condition, it came as little surprise when I couldn't get the original close coupling washer to seal properly. I was pleasantly surprised that Screwfix's sister company B&Q sold the washers separately without having to buy the metal part as well so I bought one. If you have ever seen an old and aged piece of rubber then you will know that it looses it’s flexibility and essentially dries out and becomes brittle. At this point it will have lost it’s ability to form a decent seal and will then start to leak. If Plumbers Mait or a similar sealant isn’t used or the screw cap on the hose isn’t done up tight enough onto the fill valve then water can easily leak up through the threads.I realise this is an old thread however my experience may be useful to others. I also had a siphon fault with toilet marked M360 from Ideal Standard made in late 1995. I believe the model name is Reflections or Meadow and it was designed as a 7 litre flush. This is the most likely root of the cause, however there can be others so read on to learn about how to resolve leaks with close coupled toilets. Why is my Close Coupled Toilet Leaking When I Flush??

Refit the 1 or 2 screws that secure the cistern to the surface behind but don’t tighten them too much, leave a little wiggle room. This is just to help hold everything in place and ensure nothing moves out of place. Take off the cistern lid and disconnect the push button or similar flush mechanism and put the lid safely to one side. In almost all cases there will be at least 1 screw holding the top of the cistern to the wall or surface behind. Along with the through bolts, these will hold the cistern firm and level.

Why is my Close Coupled Toilet Leaking When I Flush??

To allow water in to fill the cistern, normally a flexi hose connector is attached to a water supply pipe and then screwed on to the base of the fill valve. In some instances a flexi hose isn’t used and copper pipe runs straight to the valve. Finally have a good clean up around the under side of the toilet and floor, removing any water that could cause make you think there are leaks but there aren’t and then flush the toilet. If all is well after any inspection all should be clear and you should now be leak free. I have not yet mounted the cistern on the toilet, but I have the feeling that something is not right. If however you find that you still have a leak then you will need to remove the cistern again and apply some Plumbers Mait all around the doughnut, top and bottom. Once reassembled this should now fully resolve any leaks. With everything cleaned and ready refit, pop the brand new doughnut down on top of the toilet cistern in it’s recess making sure that it is sitting correctly and flat on the toilet pan.