Never been able to work out why my van is always a bit whiffy

Citroen Despatch.
Anyway the other night i overfilled the tank again - whoops. Nothing too major just about ten seconds of pumping. Today i'm driving about and notice water coming out of a split in the floor covering by my feet. This covering is moulded to fit and has a sponge backing - there's no way i can ever dry it out, i just wonder how long the floor will last.