Re: water inside running board!?
Whilst everyone points to water ingress through the doors, the most likely is that the water is leaking in through the box section. You accurately describe the following: on a batch of 147s the seam sealant applied underneath the front wings has been poorly apllied. Rain water then enters the body shell behind the front wing, runs down behind the door hinges and comes out of the sill box section adjacent to the foot wells. To check, roll back carpet, dry off the floor pan as best as possible and lightly sprinkle talk, especially by the cill. Take a hose and water test for 10 mins- spray water on to the front windsreen, wing door area. If you have a little stream coming out of the box section you have pin-pointed your problem. Another possibility is AC condensate, but unlikey.