[Chambers]

Just like plaaya69 said, check the lower trim piece on the hatch on the window, the lower trim piece on the hatch on my car has deteriorated, and I have one bad taillight gasket, the water every time it rains sips under the trim and sits in the bottom of the hatch, when I start driving it will slosh round a bit and goes into the spare tire well.

It's been like that for so long that there are rust holes in the tire well and the water runs right out. You will need to remove the inner hatch cover, if it is wet then you know that the trim piece is either loose or deteriorated, you will also need some deep well sockets to remove the trim piece if it is bad. Hope this helps.