My passenger rear floorboard fills with water after rains of signifigance. The only thing i can trace it back to is it started after the windshield was replaced. the installer could not get the roof to windshield deflector trim back on, I guess he bent it? But the drivers side has it and the passenger side doesn't and that is the leaking side. He says that trim is just for looks but I would swear it would have a purpose for rain direction/deflection? Any ideas (see attached pictured I uploaded of black trim I am talking about)

 

picture is not good. lol. i have seen on here t top and rear hatch seal that have leaked to the back floor. have you tried getting somone to spray wather in the areas and try and spot it.

 

For water leaks the hose is you friend. Water can snake through a great distance and the leak will show up on the other side of the car. If you suspect the windshield dry everything up and let the water run on the windshield. If there is not leak move the hose to the next spot.

Without an air leak this is how body men track down water leaks.