vw passat problem?

Question

for the past 2 days there is a large ammount of water on the floor in back,just one side,not rained ,no leaking outside under car,does anyone have a clue what it is?

Answer 1

If it is on the passenger (left hand) side then there is a good chance you have been getting water leaking inside from the pollen filter housing. If this is the case then you need to get that sorted ASAP as the water will cause damage to wiring and a control unit located on the floor.
Whatever the cause you will need to get it sorted out as water inside the car will cause additional problems and the fact the water is visible on the carpet suggests it is a long standing problem as it requires a large amount of water in the car for it to rise high enough to be visible.