My '96 Grand Cherokee was a royal pain!!! I first drilled the hole in the center of the round plastic A/C drain housing inside the car and blasted it out with my air compressor. Still had water. Then I sawed the hole, as recommended in another forum, in the fire wall near the front right tire and installed a rubber hose on the end of the short drain tube. Mine had a right angle on it that pointed downward. Still water on the passenger side carpet! Finally!!! the extra step that kept mine dry was I used some putty gunk (for lack of better terms) that is used to seal sections of metal grain bins and fitted that around the space between the fire wall and drain tube. Voila! Now no water on the passenger side floor.
Apparently, there is enough wind flow through the frame member to force the water to soak up into the carpet padding. On mine, I had to seal up the area surrounding the drain tube, because even though the right angle hose made the water drip downward, the air flow through the frame member shot the water back up into the carpet padding. What I found surrounding my drain tube looked like porous foam rubber. No wonder the water accumulated.