Internal or External leak / damp?

[Dustydog]

My Mobile engineer did another damp test yesterday on the off side front wall. Near to the Truma Ultraheat and between this and the fridge had a reading of 60% hmy:
Note the black mould on the ply floor and the rolled up lino. The black will not wash off anything. Tried all the usual stuff.
I thought there may be a leak where the Whale water inlet is placed. Testing today shows no apparent leaks. However the cold water inlet elbow to the Ultraheat was definitely leaking. I have a new part to fit tomorrow. The rest of the water joints appear ok but overnight any drips will fall onto the tissue paper.
Overnight the whole floor is now bone dry. I suspect the close fitting lino acted as a water tight seal ?

I will continue regular testing and checking of all the joints throughout our forthcoming travels.
Long term assuming there is nothing sinister going on I intend to remove the hot and cold tanks etc and lay a new piece of ply wood over the stained section under the seat. Is this a good idea?

Incidentally checking the floor underneath it's bone dry.
Externally water may have got into the wall via the fridge vents, Truma Ultraheat gas exhaust outlet or the Whale water external / internal connection. Not sure if this is the case yet.
Good job I'll be seeing two damp experts in september

Pics to follow , trouble with photobucket!

 

[Gagakev]

Oh dear Dusty, hope it is just the elbow joint.
Re; laying new ply over stained area, would this be a good idea I dont really know, but my thoughts are although dry now what happens in the winter months when the van is cold and damp, could this exacerbate the problem?
Is there something on the market to kill the spores first?
see you in September, tool box at the ready!!!

 

[Sproket]

It's quite possible that the leak has been present for quite a while due to staining underneath the lino, I wonder if it's possibly due to the water system being always under pressure rather than the older tap microswitch turns pump on in barrel system. ..either way hopefully you have found it before it's turned into a big problem & with weather like this it will dry out quickly

I wonder if you can lightly sand it down but only with a vacuum attached ?