2000 Citroen Xsara Picasso water

does the car have a sunroof? if so, there may be a blockage in the sunroof drains, this often happens as the result of road muck clogging the pipe, or perhaps some blockage under the headlining or trim, eventually the water may spill over into the footwell. if it's the drains, you just need to shove a piece of cable up it and poke it until you get a trickle of water, the difficult bit is finding the end of the drain usually the end is a plastic pipe about 7mm diameter at either side just inside the rear bumper, dont know exactly where on the picasso. hope this is no red herring.

I have same problem, also Macky prob #7641. Have been pouring jugs of water over dry car to try and track cause. Have sunroof but can't see any drain holes round it, water seems to just run off down side of windscreen then into grill under wipers (which is full of leaves and stuff, been parked under trees before I got it in January??). I think something is blocked under there, (maybe leaves etc??) though water still drains out fine behind front wheel, some seems to be going into a space somewhere and going UNDER the drivers side floor (double skin?) then it forces its way UP through the welds in the rear passenger parcel well (I managed to get the liner etc out and dry it, now I can 'make it happen' by pouring water down the drivers side windscreen only). NB all actual interior floor is dry as a bone. Am guessing there's a blockage somewhere down behind the front wheel arch, but am awaiting a workshop manual (via amazon) before I start unbolting things!

I took it back (again) to the dealer. they took out the wheel arch liner and windscreen wiper grill, and assured me that though they had looked as hard as they could all round the bulkhead, sills etc there was no sign of anywhere that water could come in. In desperation I think, they did replace the Pollen Filter, in case some may be trickling in there. Naturally (on the South Coast!) we have had no heavy rain since then so I can't see if anything has improved. Will let you know either way.

Yes it rained, same problem as before. Took it back to the dealer - again. He said they had run out of ideas, they would mastic the inside of the parcel well to keep it dry at least. My view is that wherever the water comes from will stay wet and rust, plus it may force out somewhere else with worse consequences. He said if I get rust he will fix it (though of course I have nothing in writing so may or may not happen). That seems to be about as good as it gets unless someone comes up with the genuine cause and solution. As I really like the rest of the car I may just have to live with it.

I've got a 2000 Picasso keep getting a wet headlining above windscreen on passengers side when it rains heavy and also in the footwell any ideas

I also observed Water in the small compartment at the back seats.
The Water is entering because the seal is too efficient.
The waner is running down on the inside of the door untill it is stopped by the hollow weatherstrip. The Water can only escape into the car.
The problem is easily remedied in this way:
You need to create a small opening in the weather strip to allow the water to escape down past the weatherstrip.
A wery small plastic strip is used to compress the weatherstrip in the lowermost position of the weatherstrip. Make a small hole by a nail. Push the plastic strip through the two holes and then tighten it. The Water will now be able to drain through this small channel that you have created.
PROBLEM SOLVED. It also worked on my Berlingo and on ANY CAR with this type od sealing.