X5 E70 water in boot

[dragonball2000]

Hi All, I have water in my X5 E70 boot in the same area as the battery! As the battery is mounted higher, the water is not in direct contact with the battery. The water seem to be held below the car somewhere and when I drive the car (I assume when I accelerate) it pushes the water towards the back of the car and up and through the gaps and holes in the boot. Any insights where the water might have come from? I have seen posts elsewhere saying this could be tailgate seal (doesn't look like it to me in my case) or drain being blocked (I don't know how to locate the drain). Any insights will be very helpful. Thanks.