Leaking overflow on P-Bath

[divadoll_1]

Fitted a p-shaped bath last year for a customer, who is now complaining that the overflow is leaking. The overflow is fitted to the knob that opens the waste and is high on the side of the bath...which is ok. However when the bath water is let out the subsequent backflow up the overflow pipe connected at the waste end means there is sitting water that pulls the seal out of shape. The design of the overflow pipe is such that it curls down from the overflow in the bath down to the waste but hangs below the trap. Therefore the weight of the water flowing back up the overflow pipework pulls it out of shape and the seal breaks.
We have tried supporting the pipe so that it no longer hangs below the trap and even cleaning the washers at the compression fitting, but it is still leaking a little. Other than bunging the whole lot up with some mastic what can be done? The pipe cannot be shortened as it has a smooth end with washers to fit into the compression joint!!!
IS this a design fault or can it be overcome?

 

[wonderb0y]

ok might sound like a simple question, but the overflow hose connecter isn't upside down is it? as ive seen them put on the wrong way and leak before.

 

[divadoll_1]

No it can only go one way...as it comes out of the overflow spout at the top of the bath it has a right angled bend and swoops down to a straight coupling at the trap/waste end.
Hadnt thought of that until now but looking at it, it can only go on one way

 

[wonderb0y]

i was talking about this bit

, but it thats ok then the only other thing i could think of was the anlge on the waste pipe been too steep??

 

[divadoll_1]

The waste pipe is too long as they have left it the same length irregardless of which option you take for the overflow position. This means that the pipework is too long and sags lower than the trap...therefore pulling the seal out of shape...therefore leaking. Other than cutting it shorter (which is not an option as it is a plastic waste type compression fitting) or sealing it with silicone...what can I do? I am seriously thinking of approaching the manufacturers as this is a design fault. At the moment it is supported on a house brick to make the run off parallel to the bath!
The bit you point to is not connected directly to the waste as you show it...it is connected to the trap itself, just above it, where the connection also runs for the plug release.

 

[Timmyturtle]

Cutting a plastic overflow pipe as in the picture is normal isnt it?
Coz they are universal in most cases.
Some have an o`ring at the bath waste end too (as well as overflow at top of bath)