water in pipe connection leaking at back of toilet ?

There are two types of pan flush connectors internal and external by the sound of yours it could be the external either black or white rubber.
You can leave the toilet cistern full but don’t forget and flush it when you’ve taken the flush pips off.
Go to your nearest DIY outlet or plumbing store and look / ask for the type you want [internal fit or external fit]. While there get some of those zipper straps long ones
to strap around the connector to add to sealing.
Place old towels on floor rear of pan to catch any residue water.
Unscrew the flush tube under cistern gently pull pipe down to free it from the cistern.
Work the pipe and connector away from the pan.
Remove the old connector from the pipe leaving the cistern connection collar on the pipe.
Smear liquid soap around the inside of the connector that fits the pipe and inside the large part that fits over the pan flush inlet.
Push the large part back on to the pan line up the pipe to the bas of the cistern push back into cistern and re-tighten clamping collar.Ensure pipe is push in to the pan inlet.
Once your satisfied it’s in place leaving the towels on the floor flush the toilet you should find no leaks. Any signs of leaking add the straps.


Hope it helps and is not as clear as ‘MUD’ my description.
If you already have some zipper straps try them first see if it stops the leak push on the pipe in to the collar it may have worked out a bit. Can save the above if it cures it.

Bob
February 2010