My truck came with wet soggy carpet and underpad front and back in the footwells, finally figured out that the part of the weather stripping that is supposed to close up tight around the metal was fatigued/broken/not tight - basically water was entering the 'U' part that grabs the metal at the top of the frame, flowing around down to the bottom and flooding out almost directly into the carpet/underpad.

My cheap fix for it was to pull out on the weatherstrip from the outside, squeeze in a small bead of clear silicone, press it tight to the metal, shut the door, and leave it for 24 hrs. Started at the top for the door frame and just worked my way around to the bottom. - did around the rear window later after discovering the same trouble there

Lotsa rainstorms since and no wet carpets!

 

So, yesterday morning it rained and I noticed that while the truck is sitting in place, no water gets onto the carpet - it's completely dry. After driving on the wet road, the carpet gets wet again. This is driving with and without A/C, if that makes a difference.

 

This I'm guessing is relative to the water dripping from behind the protective barrier in the wheel well.

 

I had a similar problem in my blazer. It was the passenger side rear floor. I chased the leak problem for a long time. A leak where you fill up a shop vac to get the water out. I had looked everywhere for the problem. The wheel well looked fine, weather stripping fine, it wasn't until one frustrating day I actually crawled under the blazer and found where the metal floor pan was welded together, a seam had opened up. Just barely....filled it with silicone....6 years later, still no leaks. Just an idea of something to check out.