hi there,
two things the heater matrix might be leaking or the door seal and if you have a sun roof its most proberly that common fault.lift the carpet up and under lay and pull out the plug on the floor if it fills with water and its not been raining then its the matrix,if it fills with water when raining then its the door seals or sun roof if you have a sun roof its most proberly that a common fault.
ian
March 2010