Leaking Boot

[Gav88]

Hi, I'm new here so I am sorry if I have posted this in the wrong place!

I'm after any help and advice people can give regarding a leaking 2004 Ford Focus boot! I am aware that the usual suspect for this problem is the tail lights but I'm not exactly sure where abouts...having removed the tail lights I can't see anywhere water could feasibly get in. All the seals look good, and it's pretty much bone dry under there! 

 Also, the water seems to be collecting mainly in the bottom left corner of the boot, where the corner panel joins onto the main body of the car, there's a lip there, just in front of the body air vent and it normally pools in there, with some managing to make it into the boot compartment proper. But also, I've found traces of water from the lip end of the boot all the way to the back near the back seats...wondering if that's just from a wet carpet? Or is there a known fault that could cause this? I'm wondering if it's the body vent? Any help you could give would be appreciated. Thanks. G

[WES180]

Grease the foam on the rear of the lights to ensure a watertight seal.

Check the tailgate hinge and damper fixings.

Check water hose for rear wiper spray hasn't split.

Check rear wiper arm seal.

Check any body panel seam sealer hasn't cracked.

Remove cavity vents and refit with a suitable sealant.

It's bound to be one of the above. Best thing to do is sit a running hose on the roof and see if you can trace where the water is entering.

I know yours is a 2004 but I had this problem on my mk3 too.