leaking close coupled wc

[gpw20]

Can anyone tell me if there is supposed to be water (nearly touching the brim) in the rear chamber of the toilet bowl where it connects to the cistern?
We have had the doughnut seal give out on two occasions - 3 months after first installation and again after 7 months after it was dismantled and reassembled. The leak happens all of a sudden and I believe it has something to do with the water in the rear chamber because it is in contact with the doughnut seal and must put the seal under pressure when the loo is flushed. I am sure the chamber shouldn't have this amount of water left in it and therefore think it is a casting fault but at the moment Ideal Standard don't want to know.
I will be grateful if anyone has any ideas. Thanks

 

[Burnerman]

There should be no water there, so either its the doughnut washer again, or maybe the bolts that pass through the cistern if it uses that connection method.
Its important to keep the cistern perpendicular to the pan, and I always use a good squeeze of silicone on the doughnut - which shouldn't be really necessary.
John

 

[gpw20]

Thanks Burnerman,
The bolts are fine, the pan is level and the cistern is upright and unstressed. The leakage does occur from the seal. Yep I can replace the seal again but I am sure it leaks because, as you say, there shouldn't be any water in that chamber/space at the back of the pan. You would normally expect all that water to go into the pan on flushing, yet it is nearly full to the brim and I there is no obvious blockage. To me it looks like a design fault - this is a new design with Ideal Standard's 25 year guarantee but Ideal Standard's Customer Care don't seem to care.