Fluid leak inside car

I looked behind the glovebox at the passengers wiper pivot and saw no moisture. I went and poured water directly into the cowl vent to make sure i wasn't misdiagnosing. I see the same leak which i thought was the pivot seals. Both cowl drains were obstructed to just a trickle. I cleared both sides and water now drains unobstructed from both sides of the cowl. As for the leak which comes down the corner where the firewall meets the fender on the passenger's side. is it likely I have a rust through in the cowl or was the high water levels in the cowl previously over flowing into something? Leak seems to be localized to the far right passenger's side possibly behind the heater box.