rooftop vent pipe full of water

[MikeH]

A client has a 2-storey house, with 5 2" vent pipes emerging through the roof. Each has a 90degree bend on the top.
4 are open and breathing OK.
The 5th is full of water!
Any thoughts why?

Further info:
- each vent serves a toilet
- this particular vent serves a toilet on the ground floor
- the 90degree bend is glued on, so not easy to see inside
- there are sparrows about, with some nests; but it seems unlikely a nest (down out of sight) would plug the pipe well enough to allow water to pond there (there has only been a little rain in the last few weeks; this is in Cyprus)
- I expect I will have to saw-off the 90degree bend and carefully look/probe inside -- but if there is a blockage, I don't want to push it further down
- there is no access to the lower end of the vent pipe

Regards,
Mike

 

[justlead1]

Hi
If you can access the pipe further down? Why not drill a series holes with a very small drill (say 1/16th) easy to repair with a bit of solvent weld. This will tell you where the water it, which will identify the area of blockage when you strike air. Then perhaps an access point can be introduced?
Where the water is coming from is the mystery.
Good Luck

 

[MikeH]

justlead1,

Thanks for your thoughts.

Unfortunately, the pipe is buried in the solid concrete/brick walls and foundation (no, not even any trunking/boxing in a corner/wardrobe). So I have no idea how the vent pipes are actually connected to sinks/showers/toilets. There must be sub-horizontal runs here and there.

I shall check that sinks and showers are draining OK, and if so, presume the blockage is above the uppermost one.
...Not that that would explain the thing being full of water.