I've spoken to my friend who had almost the exact problem, and his problem originated from water leaking into the well through the vents behind the rear bumper on the rear corners of the car. Even though the vents look as though they're positioned to not allow water in, the seal around the vent to the body had eroded. He resealed them and hasn't had any water since. It may or may not be the same problem as yours, but at least it's something to check out.

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Air is for pussies.