Jaguar S Swimming Pool

My pal Rich as a Jaguar S luxury sedan. When it rains long and hard, the trunk fills up with water. Sometimes, a lot of water!
We took a long look to try and figure out where the water is entering the trunk but we’re baffled. The weather striping is in good condition and everything seems tight. We did think about one of us getting in the trunk and the other putting on the hose but we are having trouble deciding who’s getting in the trunk. I heard this jag problem is not unique. Wonder if any other Jag S owners have figured out where the heck the water in getting in. And how to you stop it!?

Put a few pieces of cardboard in the trunk - enough to cover the entire floor. Then use the hose on the trunk lid gap and the rear window. Look at the rubber seal on the window. Is it seated completely into the gap? If not, that can be a leak. Another possibility is the rear lights; maybe even a sun roof if he has one. But start at the lowest point and work up, and check often.

Thanks for the good suggestion. I will be trying that.

If the rear seatback pops down (most do), you may be able to see in there while testing it with a hose. But these sort of leaks can be hard to find. I once found one coming from a small chip in the corner of a taillight and migrating into the trunk area.