I've been driving my 2016 XF for a few months now (~11k miles). Recently went away on a business trip and had to leave the car at the airport during some rain. Not a torrential downpour but steady rain. So I returned 3 days later and while stopping I hear a sloshing noise from the passenger side. I am searching thinking my girlfriend left a water bottle under the seat and nothing. Well, I open the passenger rear door and immediately I catch the culprit. Shake the door a little and I can hear it sloshing around. Time for a dealer trip to check if there has been any reported issue on the window seals and hopefully a simple drain plug empty the contents.

 

There will never be an ideal seal between a door and a moving glass. That why there are draining holes at the bottom of all doors. And in your trunk too BTW.

Anyway, looks like those holes are plugged. Did you do sound proofing by chance? Or maybe just a dirt...

 

Exactly right - the drainholes at the bottom of the door are plugged. Just get underneath with a wooden or plastic pointy thing and unplug them. It is perfectly normal for water to get into the doors - that is why every door has drainholes!
This is not a dealer issue and rectification will take not more than 3 minutes.

 

You gents were exactly right. I suspect that doors drain holes were clogged for quite sometime. After opening them up I had a steady stream of water for several minutes. To me it appeared to be at least 2 liters. Easy resolved, Thanks for your input