My toilet seems to block up a couple of times a year - it's never the WC pan itself but always outside.
On flushing the water rises up inside the pan and then slowly drains away.
There's an inspection pit where all the drains meet - the outflow to the main sewer gets blocked - big iron lid. Look in there first. If that's the problem it will save you time. If it's not the problem you will have wasted two minutes lifting the lid.
The outflow will point towards the road - you can sometimes clear it with a long stick - pulling the obstruction inwards works better than trying to push it outwards. Wear rubber gloves.
Good luck...
Peccavi, October 2009
