Volvo Forums - Volvo Enthusiasts Forum - Water leaking under rear seats??

I have researched this issues a bit on Volvo forums and see that water leaks are pretty common. Living in Seattle, this has been hugely annoying. We have a 2005 Volvo V50 T5 with about 120K. We recently moved to this rainy climate from sunny California, and our leaks began. Initially, we had a major leak and the front passenger mats were soaked. We then discovered the rear area under the seats (not on the floor of the car, literally underneath the rear seats) was also wet.

We had the sunroof plugs modified and replaced. That took care of the leak in the front of the car. But, the leak under the seats is persistent. They discovered some other weird leak and that the sunroof was off-track. So, they took the entire sunroof off and put it back in.

That didn't fix the leak under the rear seats. We did observe that everything stayed dry even in the rain when the car just sat in our driveway. When I started actually driving around, that's when the leak started again. It may be coincidental, because that's also when the heavier rains started. Is it possible that water is kicking up from the ground and getting in there? I was driving through some very wet streets when the issue began again. Anyone have a similar experience? It's a huge pain since each time, we have to get the carpets dried and it takes about a week to do so. As far as I can tell, nothing it getting wet except that thin black carpeting material near the seat belts, under the seats.

Thanks for your input!!