Or it could be a simple fix of a nut being replaced on the leaver at the top.
This isn't a good idea as the water drain is also the gas vent.I think I would get underneath and plug the drain / exit!
I edit a message which was wrong after looking at cutaway sorry for thatAndy - (got the mail notification but cant see your entry here).
The issue is how to access the valve at the bottom of the tank?
That would be worth a look.diagram here:
http://www.oemepc.com/vw/part_singl.../068/subcategory/68030/part_id/3706722/lang/e
Is the pipework and valve at the bottom accessible from underneath, once the undertray is removed?
REMOVED STRIP FACIA ALONGSIDE WARDROBE
The VW California Club is the worlds largest resource for all owners and enthusiasts of VW California campervans.