MK3 focus zetec s boot leak.

Hi all,

new here. I have done loads of googling and am at my wits end with where the water is coming from in the boot area. 
 

firstly I thought I got water in my passenger side rear footwell from my pressure washer as the door seals have been hanging out the bottom of the door for quite some time so I re stuck them on. 
 

however after any rainfall there’s always a little puddle bottom left in the boot liner and the wadding material is all wet. I read it could be the seal from the screw fixings so I greased them up but to no avail still leaks. I also read to pull the plugs out from under the vents behind the bumper which were full of water. 
 

my parking sensors a couple of weeks ago decided to come up on the dash as “parking aid malfunction service required” but will only do it 1/3 times I start the car. 
 

I stripped all my boot items out today and looked underneath the car for all the  sensor wiring and couldn’t see anything untoward. There’s no water in my spare well although is rusty looking where there must have been some at some point. But the left hand side wall carpet lining is drenched. I also had another look inside the light hole area and maybe concluded it can only be coming from the strut mount? As it’s wet higher up than the fixing locations for light unit. 
 

I just want to get this sorted now, but don’t really know how to approach it going forward as obviously I suffer from terrible condensation every time I get in the car. 
 

hope anyone who has read can help me out, will be much appreciated.