'Cuse me if this has been covered. Newbie here.
I have a stock 2003 S-10 3-door. When it rains heavily I get water collecting in the driver side floor pan starting out as damp carpeting. If it rains enough it will actually puddle up and the water will extend into the floor of the cargo area behind the driver seat in the form of wet carpeting.(Notice that all of this seems to be happening on the driver side.)

It seems to be seeping into the passenger area rather than dripping in. I can find no wetness anywhere under the dash and I've never seen a drop of water fall from under the dash. The wetness first appears in the floorboard carpeting just in front of the driver side door right up against the side wall. I don't know if this is where its coming in or just the first place it becomes visible.
Any help appreciated.

 

I have an 02 that leaked. Check your door seals (there are 2) 1 is just a seal that pushes on the pinch weld and the 2nd is just above that it is 2sided taped in to a chanel.that was the one causing my leak. Pull it off and peel off the tape and stick it back on. Also do you have a sun roof?