Over a gallon of water in passenger well? Liberte 1.4?

The car was on the drive for some 4 days. Apart from the large amount of water in passenger well there was also some in the back passenger well and a small amount on the clutch side (driver's side)I am thinking that all this water may be coming from the heater system. I do not think it is rain coming in from door seals as the seats are dry. Any answers ?