Water collecting under C pillar

[Westy End]

Hi all,  I am installing some insulation and in the process I discovered that the void behind the panel just to the front of the rear wheel arch is full of water. I can’t see where it might have come from. The rear window doesn’t leak into there unless there is a hole in the bodywork but I have just had the windows done. Might the slider mechanism fixings for the sliding door be leaking rainwater?

any ideas welcome. 

[RogerT]

There’s a hole (for inspection?) just above the trailing arm/jacking point mount, that should have a rubber bung in it.

Your van may have a hole with a bung / a hole without a bung / no hole (as a result of a previous bit of welding) / a rusted out hole.

Or, perforations higher up in the wheel arch, or holes in the inner sill, or all of the above

[Rik]

I had water there too. It was the air vent higher up the side, to the rear of the sliding door.

[Westy End]

Thanks - it does have a rubber bung and it is intact. I have put inner wheel arches in so not much water can get in that way. 

as to the air vent - Rik - was it the one that is inserted into the window (I have a Westy with this) or do you mean the one at the rear which leads to the engine?

[Rik]

as to the air vent - Rik - was it the one that is inserted into the window (I have a Westy with this) or do you mean the one at the rear which leads to the engine?

This one:

Although it's probably not there on vans with windows all around?