Water in vehicle

Hi, recently bought a JB74 LCV. We seem to have a possible issue with water getting into the vehicle. It only seems to happen when we have a lot of rain and only down one side. I joined this group and did a search on the forum and came up with a post from 2013 regarding what sounds like the same issue, of water that seems to be sloshing from the back to the front down by the drivers side floor.  The post mentioned that after a bit of investigation he found the sill drain holes blocked.  Armed with this info I took off the plastic trim on ours and had a look. No water as far as I could see and the plastic plug holes holding the trim on are at the bottom and they looked dry as well.  I checked the door drain holes were ok and put the trim on and moved the car onto level ground (our drive has a slope and the Jimny was parked back end down ) and a small puddle appeared under the front mudflap. It is going to the garage tomorrow and we have already mentioned it to them.......and got the usual "well we have never heard of this happening before" so not holding out they will find the problem. Has anyone else experienced this issue, I have no idea if the floor pan has a double skin or cavity which may harbour a large amount of water, which it must be as we can hear it moving around for over 1/2 a mile. Bizarrely we don't hear it running as soon as we move off. It starts after a couple of hundred metres.
Thanks in advance for any thoughts.

Water is collecting somewhere when it is parked (back end downhill) and this then flows to a drain at the front when on level ground.

Is it on the roof and in the rain channel, this drains to the front?

What happens if you park it the other way on, i.e. front downhill, my guess would be that it doesn't do it then.

My Jimny is parked on the flat, but my other car is parked on quite a slope, whenever I get this off the drive water comes out everywhere as it collects on the boot, bonnet and both doors.

Robin

Have you actually got wet carpets, or is it just the sound of running water?

Rain from the roof will run forwards and down the A-pillars & windscreen, this then runs in to the drain channels in the front scuttle panel, this is where it sounds like running water, this exits the body from the wheel arch area.

As Soeley said have you seen water inside or just heard it? The new Jimnys roof drains means water runs off around the car so you can hear that travelling usually just after you’ve set off. Now Jimnys do suffer with condensation inside and I have noticed sometimes you can get the odd drip from the around the rear view mirror area although never seen any signs of wet headlining. They are bare metal the other side of the roof lining so usually that’s soaking wet if you were to remove the headlining. 

Hi, I only mentioned that it had been parked on the slope as I wanted to see if the water would pool at the rear of the car. Most of the time its parked on the flat. I have checked to see how much water has collected on the roof, but the sound we get when driving sounds like a flood of water.

Hi there, no water in the cab at all, we only hear what I think is a small lake sloshing around for about half a mile and then it stops. when investigating around the sills all the holes were dry. Will see what the garage comes up with. I think more investigating will be the way forward.