Got water coming into the back footwells and i read the cause of this could be the membranes in the door. Were are these membranes could anyone tell me or post pics thanks. Any advice would be helpful thanks. My car is a 02 skoda octavia.

On the passenger side this can be caused by a grommet next to the pollen filter under the scuttle panel. A quick search will reveal all.

The door membranes are in the doors, simply remove the internal door trim, and there should be a plastic covering. These often get cut/damaged when locks or the window glass is replaced.