Water in drivers and rear passenger footwells. all solutions mention sunroof drainage pipes being blocked. I HAVE NOT GOT A SUNROOF!! nothing is leaking from tne engine but my manual does not show

there is obviously a water leak . does vehicle have sunroof ? if so make sure the drainage pipe's are clear , one out let in each corner of tray when sunroof open are clearly visable, to test carefully pour some water down the pipe outlets and check for the water draining to the floor usually around the wheel arch's , very common for these to get block by road debris , mud etc so water can't escape quick enough , also remove the A pillar trim and check that the drain pipe is still connected to the outlet from sunroof

have you a sunroof ? the sunroof has drainage tubes that run from each corner of the interior sunroof down the inside of vehicle and exit so water should escape out from sunroof well, if one of these tubes is blocked,split ,out of position it could easily let the water into the vehicle ,if you dont have a sun roof there may be a poor hatch seal letting water through the boot area into foot well , is the spare wheel in the boot area ? if so check if there is water there as well, keep me posted if you wish

If you don't have a sunroof, then your windshield is leaking. There are no other drainage tubes

look on hooded vent area( under windshield whippers) sometimes there is a drain line that gets plugged with leave and dirt use a air line blow through and clean out this should do it

all sunroofs have drain pipes, usualy 4, one on each corner, they usualy run down the A pillars at the front and poke out near the kick panals by the footwell. the rears often run down the C pillar to the vicinity of the boot.
open the sunroof up and carefully pour lots of water around the drain gulley of the sunroof, you should see it pissing out onto the floor at the front and rear on each side. make sure water goes down all 4 corners of the sunroof and check. Pipes can come of at the roof. also the drain grommets block up.

common problem on passats also is the pollen filter housing letting in water (under the scuttle panel beneath the bonnet. on left hand drives though, this fills the passenger side only (left). not sure on RHD which side pollen filter housing is on , but when they leak the water fills up inside the car on one side only, which can flow front or rear depending on car being parked up or down hill.
the seal between the pollen filter housing and the bulkhead often leak, if you press down on the plastic housing you may hear the seal squelching water. there was a recall on this, so it may have been done.
If the comparment under the panel (where the battery is) is filling with water, there is a drain grommet under the batter that also blocks up sometimes, causing it to fill up and flow in where it shouldnt.

If you have a sunroof then the problem is most likely a drainage problem with the sun roof. The drains are blocked and the water is running down into the car.

The under the dash thing is the only thing that worries me. That is usually the location where the heater core will leak to. Are you sure it is water and not coolant? Coolant gives off a sweet smell and when it's hot you know cause it stinks.

But my money is on a sunroof leak and drainage problem if you indeed have a sunroof.

Generally with the sun roof, If you open it and look in from above, If the drainage is blocked you will see excess water that wont go away. If there is no excess water then the chances of it being a blockage are minimal, its more likely to be a gap in the rubber seal allowing the water to seap through to the interior. If it is the seal, which i guess it is as they crack over time, then these are generally quite cheap from your local motor store.

The sunroof drainage gets blocked.

your footwells will fill with water - even under your seats right to the back seats footwells

See two 10mm holes in front sides when sunroof is open.
a) push a flexible cable down from the top - it comes out just behind the front wheels. (use electric three core cable - or TV aerial cable - a hanger is too short) - you need about a metre and a half)
b) remove the inner mudgaurd behind the front wheels (2 screws) you will see the end of the plastic drainage pipes - remove the blocked black rubber cup at the end of these - why they are there is anybody's guess)