MC 2014 Mondeo wagon rear drivers side footwell wet

[Brettnell]

Hi all this is my first post on here.
I’ve been noticing a wet musty smell for a couple of months and it was a soaking wet footwell behind the drivers seat. I’ve since dried it out and checked all the seals and trims on that door but in the last downpour there it all is again. The carpet feels pretty dry the further fwd I go into the front foot well and in the last downpour I got inside the car and looked at the seals all around the passenger rear door and could see no dripping or moist areas. I also checked all along where the carpet runs up and under the plastic trims near the bottom door seal, it felt damp towards the back end but no visible clue how water is getting through from outside. I found no evidence of a leak up under the dash near the pedals and the carpet feels pretty dry there. The cargo floor behind the rear seat also felt dry.

We live in a hilly area so the car parks on a slope with nose and drivers side being the high points (in the downpours yes) so it’s possible the water is coming in further fwd in the drivers area and running downhill but since the carpet up forward is not wet I’m at a loss.
Please help I’m getting tired of vacuuming out water and drying carpet.
Thanks