water leak

98 Regal LS

I have a previous post (re:ignition harness) that led me to finding that water was leaking in through the cabin air filter. I have fixed that. However, I am still getting water in the right rear passenger area. I believe that it is coming from the back. The carpet by where the right, rear seatbelt bolts to the floor is very wet and the foam of the rightside, rear passenger is soaked. I don't believe that this is coming from the front. There is water on the right,rear floorboard, but not a lot. I cannot find where water is coming in. the trunk is dry. I don't find any problems with the door seal that would be letting water in. (There car has not been driven on a wet road.)

Any ideas as to where this water is getting in?

Thanks,

Bill