Had this problem and found that the water was coming out of the rear air vents under acceleration. Turns out the whole vent system was full of water.
Drilled a small hole in pipework to drain all the water out.

I just laid towels over the seats behind the rear vents to catch the spray and directed all the airflow through them at max fan speed and max temperature. Cleared in a reasonable time, after a lot of gurgling and spraying.

To clear the vents of water, or rather the centre tunnel that feeds air to them, the best/quickest way I found was to use J-cloths:

Remove the rear vent first (couple of screws and plugs, takes just seconds). Then, using a continuous roll of J-cloths like this tear off a length about 2-3ft long. Twist it tightly and keep turning it as you poke it down the vent. Repeat a few times until the J-cloths come out dry.

Use duck tape to attach small hose to vet&dry vacuum cleaner and suck it out.

No more water
 

Well since sealing that hole...... and front is now totally dry, rear was still wet but having lifted the back seat to pull carpet up... and switching tea towels every few days... that nearly dry too..... or course had it been summer would already be dry but.... getting there....

have had rain and nothing so far......

time will tell for sure.... but deffo looking good so far.,...


Do no doubt this has been the problem with mine for many years as I can remember the pass side being wet (on and off) many years ago .... on and off..

So I'd say even if ya have a dry interior ..... then come summer time, might be worth poking around and make sure that hole is sealed well..

Daz

Finally sorted.
 

So I left the car parked up all winter under cover and since its been out the last couple of weeks with some rain there was again water in the foam of the rear footwell.

It turns out that this hole to the right side of the ECU box under the air con pipes was leaking in water. It was coming in to the passenger footwell and then traveling to the rear in a recess that I had missed before when I checked for moisture in the front.

Since I plugged the hole with a bolt and plenty of sealant its dry! +++

Thanks for all the pointers, I would never have found that with out the references.

Will get the car ready to sell it now as the D3 just arrived :cool:

That sounds like the infamous "Botang's hole"! :ROFL:

i have water under my drivers matt? any idea, the whole matt the sponge bit gets soaked through

Most likely either blocked drains under the bonnet or your aircon drains. I would check your drains under the bonnet first. Look for standing water either side, just under the window. Also the centre drain: Shine a torch down the side of the cabin ventilation intake and look for water, or get a hose and pour some water down to make sure it's draining away.

I have the same problem
 

Hello.

Same problem for me here, always dampness at the rear of the passenger footwell with no obvious source except perhaps the door seal. I put some rubber "gummipflege" on the seals allround as I can only think it's the door, weirdly the wet patch only stems from the rear centre of the foot well and there are no obvious ingress there, cowls are clear, driver side is fine.

I am veering for the door but It's not too drastic...