Why is water leaking into drivers foot well?

Answer 1

Clogged drain. Either sunroof drain or possibly one at the cowl panel. Google the problem for your specific car, find out which one has been known to clog then unfold a metal coat hanger and carefully poke it out. be careful though they usually have rubber boots at the top to direct the water and if your just stabbing the hole you can knock that boot off. Good luck