The doors dun't fall oft when wet. :doh:
Water under carpet could be coming from loads of different places. If the cover which allows access to the top of the fuel tank isn't fitted or someone left the screws out then water will get in when splashing through large puddles. If you heater matrix leaking? Water also gets in via the tailgate window if the seal is crap. Also if you drive through deep water. Also when the sunroof drain tubes are blocked. Also when the car is damp due to condensation if there isn't enough air flow like when the rear vent is blocked:
http://www.landyzone.co.uk/lz/f9/tired-condensation-front-windscreen-67379-5.html
To get the water out the front you need to:
Remove the plastic around the front door aperture at the bottom.
Remove the plastic next to the door aperture plastic on the side of the seat.
Unplug the electrical connections to the seat under the seat.
Remove 4x torx bolts holding the seat.
Remove seat.
Pull up carpet around the edge (remove plastic cap holding in place under the pedals) and squeeze to get most of the water out of it. Then mop up the water with a cloth.
You may need to disconnect your cruise control computers under the driver seat (if fitted) and remove the metal work they mount on to allow you to lift the carpet more.
Now do the same to the passenger side/seat if you have water there too.
If you have water in the boot, the boot storage box or under the boot carpet then:
Fold the rear seats forward and up.
Disconnect all the plastic cap things holding the carpet down.
Undo the torx bolts holding the carpet down along the tailgate opening.
Open the boot soorage box and undo torx bolts and remove lid.
Pull up and out the carpet covering the boot floor and squeeze as much water out as you can. You may want to remove the plastics around the boot area to do this. The carpet will pull out without this, but you'll need to remove them to refit the boot carpet.
Mop water up in boot space.
Remove plastic around the rear passenger doors (if 5 door model) lower aperture.
Pull the rear passenger seat carpet forwards as some of it tucks under the rear seats into the boot area.
Squeeze and mop rear seat carpet as before.
Put a dehumidifier in to remove all water from inside the car. I've been doing this recently as I left the screws out of the cover over the fuel tank access. Water has been splashing up and getting in. :doh: It helps if you put a fan in there to swirl the air around more, to help the water evaporate so the dehumidifier sucks it in. When it's dry inside look for sources of leaks with a watering can if required. If not then put it all back together.