Wondering if someone can help me with this issue, I just bought a lightly driven 1999 honda civic SE with roughly 120,000km that was driven in the west coat of Canada (no rust). It's been raining like crazy over here (7 days a week) and the other day I noticed some wetness/dampness by accident when reaching underneath the seat to hide my dash cam. The area where I've noticed wetness/dampness is in the footing area for the seat directly behind the driver seat and directly underneath the driver seat.

I would liken the amount of water to how your clothes feel after you just washed them and before drying them, maybe a tad bit more water than that. Imagine dunking your shirt into water and then wringing it out, thats the kind of wetness i feel after 7 days, nothing alarming like puddles.

There appears to be no water anywhere else, I checked the passenger side footwell, underneath the passenger seat, and the rear passenger seat. Also, there is no water/dampness for the driver side footwell or even the front seat mounts. The carpet that goes up to the rear seats are not wet either (see photo). I am wondering, is it possible for water to leak through the bolt that mounts the driver seat to the frame?

1. I removed the plastic cover that hides the seat belt along the B pillar to see if maybe water was running down that, it was dusty, which leads me to believe no water runs down it.
2. Door seals look good as well
3. Windows were rolled up and double checked

Wondering if I need to unsrew the bolt and add a washer or teflon tape? Or has someone experienced this and knows what the problem is? thank you for your time!

 

check your roof rain gutter. the factory seam seal might be broken

 

Maybe the bottom drain holes are not sealed properly like it was in my case

 

Check door seals.