Stumped - can you guys bend your head around this one - water going from the loo

[Triple]

Can't fathom this one - what d'ya think? Water is pulled from toilet u bend, have replaced the durgo valve, tried it with no valve and tried it with vent pipe sealed - no difference, water is pulled out over apx 30 mins.

I can see down the vent pipe and can see the water leaving when flushed - so no blockage above toilets. Water goes away quickly every time toilet is flushed so no sign of blockage down stream.

It's happening on the top floor of a three storey house in the main bathroom toilet, there is another toilet on the other side of the wall (en-suite) which does not have same problem. Been fine for ten years, problem started apx three months ago.

Thanks guys

 

[steadyon]

Two possibles I can think of:

a. Leak from WC under floor.
b. Piece of cloth or the like "wicking" the water out.

 

[drip-dry]

If no blockage maybe pan trap cracked or miscast internal maybe

 

[kris]

Only thing i can think of is either small crack leaking the bowl straight into outlet end or syphoning action , certainly is a strange one ,,

Welcome to the forum Triple

 

[dancinplumba]

Usually half of water left if by siphonage

 

[REDSAW]

put a new pan in!!

 

[DrainMedic]

If all the water is draining away, then the bottom of the pan is cracked. If it's a back-to-wall pan, it may not necessarily end up with the floor becoming wet.
The fact the other pan is not draining, and you've removed the AAV, means siphoning is ruled out.

Two things I've had in the past, although 30 mins to lose the water is far too quick for either:

Firstly, while working at Drain Doctor, a chocolate Labrador drinking from the pan had me re-called 3 times to a downstairs toilet smell with the water being lost over a 12 hour period each time. I was working at DD, not the dog!

And secondly, a back to wall pan mounted as an afterthought onto a floor with electric UFH, the coils had been installed below the pan and had escaped being drilled into, although they evaporated the water over a 3/4 day period. I suggested removal of the pan or more frequent flushing as it never used, but the shop owner resorted to filling pan with sand!

 

[jtsplumbing]

What's changed in the building in the last 3 Mths ? Crack in pan seams most likely

 

[Triple]

Clever, steady on, you were right. I took toilet out in the end and found that someone had put a hankerchief down there, it got caught and was looped over the u bend transporting the water out.

Thanks for the hint.