Water leaking from under back seat during heavy rain!?

Here's a new one. Can anyone help?

During a heavy rain, when parked over night and not in a place where water puddles, water seeps in from under the back end of the backseat carpet. It seems to be coming from the plastic above the end of the carpet that goes up to the seat, in front of where the battery is.

This is the second time.

It happened before without my knowledge and caused a stink. Took weeks to remove the smell.

This time I caught it and am wiping up as best I can.... but where the heck is this coming from and why NOW??? I've had car for 4 years. Did a mechanic forget something, did I hit something underneath? Is it from above and leaking down?

Help!

Thank you.

tom

 

Thanks. Nice to know I'm not crazy. I did super inspection, and sunroof seal looks tight. Even took out everything down to spare... all bone dry. So I googled around and found this from a bmw owner:

During a heavy or prolonged rain (or carwash) water collects on the rear interior floor boards. There appear to be two major causes for this - mine had the more frequent of the two. One is that the sunroof drains can get clogged. The drains run down the c-pillars just behind the rear doors and if clogged the water backs up and runs down onto the floors. The other, more frequent issue is a torn or unglued noise baffle/vapor barrier that is in each rear door. Rain water goes down inside the door at the bottom of the glass and that vapor barrier directs the water flow to a drain at the bottom-front of the door. The glue/sealant that holds that barrier to the door frame can go bad - when that happens the water goes inside the car rather than down the drain. Re-seal the barrier and the problem goes away. Be careful to do research, or take it to a pro if you have rear door airbags - if they deploy while your head is in front of the door it can kill you. For a car w/o airbags like mine - it took me about 20 minutes for each rear door to remove the door panel and put new sealant on the barrier.
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Now I at least have something to say to the dealership. It has to be one of these two things as you suggested.

much appreciated.
tom

 

To BMW's credit I believe it was 2012, maybe they've fixed. Yes, I wanted to the off the plastic skirt around back seat but was put off by the round plastic looking bolts that clip it in. I could experiment with pliers and pull and twist but didn't want to break.

I've had this 2015 since april 2018, never had a problem. If there are plugs they would have had to fall out, and would need to know more specifically to look.

I confess to not figure how the water from the door can go anywhere by down and out.... but if water come into the door at the glass and is shunted out, I can't figure how it ends up in the back seat either.

Well, another soaker coming Saturday.

 

I at first thought it came from bellow the car when the street curbs were flooding. But the second time it happened it couldn't have been from rising water from below. It had to have come from the rain fall.