I had a similar issue, turned out a grommet behind the arch liner had come out some how allowing water in to the inner sill area which then seeped in to the floor pan area,
I have the same problem at the minute too..... my carpet is wet on the drivers side. I looks to me its slowly streaming down the seam on the right of pedal? are there always leaking from here? it isn't too bad and waiting to get down to a body shop so than take off the wing etc and sort it.