My '91 Honda Civic gets water on the left rear floor every time it rains AND I park uphill. If I turn it around and park down hill- no water on the rear floor. I can't find any bad gaskets around the doors, windows, so I think it may be entering around the hood area and running back under the carpet- front to back. The front carpet is not wet but does feel slightly damp in places. Are there drains holes that get clogged up somewhere? Or is there somewhere else I should look?

Also, when I open the trunk water comes out from the trunk lid - again clogged drain holes? I looked though my Chilton's manual and find no reference to drain holes; likewise with a Google search??

 

get a friend to hose it down while you're inside, or run through a car wash ans see if you can tell where it coming from.