I have a Toyota Aygo which leaks water into the passenger side foot space, so that when it rains, about 2 inches of water collects where the passengers feet would be.
It’s been in to the dealer three times to fix, they replace the door seals but it seems to me that the rain isn’t coming in via the door or window, but up through the floor somehow, ie seems to come up through the carpet suggesting it’s coming in from somewhere else!
PLEASE please help!
That seems like a bunch of water. Is the A/C drain line clear. You can blow air up the little rubber drain line to clean it out yourself or run a fuzzy pipe cleaner up it. What year is this vehicle?
It’s also possible one of the body seams near the firewall isn’t doing its job
Do you have a sunroof?
There are drains at the bottom of each door, start with the passenger side door and check that the drains are clear. Do this first because it is easy even though it is not likely to be the problem, but there is that chance that it is.
Next. check the drains at the ends of the cowling. Open the hood and look at the base of the windshield on each corner, there are drains that go through to the ground, they need to be clear. A garden hose aimed at these corners should not back up water. You should see water hitting the ground behind the fender just before the door.
Then remove the cowling, the panel at the base of the windshield between the windshield and the hood. Under it on the passenger side is the intake for outside air. It should be shaped like a horn about an inch tall. Look for any rust around the base of this horn. If there is any, seal it up with silicone caulk.
the rain isn't coming in via the door or window, but up through the floor somehow
So, if the car sits out in the rain and is not driven, NO water appears in the car, right?
All good comments above. It’s surprising leaks like this don’t develop in all cars if you think about it. I mean you drive at 65 mph in a rainstorm, that’s like the car being in a hurricane. Here’s the trick: The car’s designers don’t even attempt to make the car water tight. They know that would never work. Instead, they design it to leak any water out that gets in. The windows are the most likely place were water gets in, as they must go up and down, so the seal isn’t watertight at all. But there are drains at the bottom of each door – as mentioned by @keith above – which allows the water to drain out as fast as it gets in. If these drains clog up though, then the water won’t drain out and will go inside and end up on the floor.
Every surface on the car has a path for the water, if a rain drop hits there, to drain to the ground, somehow or the other. So think of this as a puzzle, and test the various surfaces on the car to make sure all the pathways the water drains to the ground are clear. If you have rust holes in any of these paths, that’s another way water could get into the car and to the floor. Best of luck.
This post may be from the United Kingdom, I just wonder how much rain it would take to put 2 inches of water on the floor board. I almost suspect someone is pulling a nasty prank (vandalism) on the person.
could the windshield be leaking?
Has the car ever been crashed or the windshield replaced? Are you in a area that rust is common? If none of the above are considerations there are a few other possibilities a/c drain plugged, door seal not installed properly, moonroof drain, if this is a new car have all the body plugs checked. If you can you can pull back the front carpert and remove the lower trim panels have someone spray the car with a hose while you look for the water from the inside. Concentrate at one area at a time until you find the leak.
Thanks for all the possibilities, here’s a bit more info. The leak started happening after the door skin was replaced after the car was broken into. It happens only when it has been raining, but not always, and it can happen whether the car has been driven or not. It is under warranty still and so I don’t want to be messing with it but I will check for the drains as suggested. The water does not drain away, sits in the cavity. Car is a 2011, yes in the UK and it’s not raining that hard in London, despite what you may hear!
Another idea. There’s supposed to be piece of plastic that provides a water-tight seal under the interior door panel. Maybe that has come loose or is missing. Since the car is under warranty let the dealer do the inspection, as removing the interior door panels can be challenging without breaking something in the process.
yes to all this - window scraper, ports at bottom of door, plastic membrane inside door - I’d add to look for vents on the edge of the door (might help), shake the door - any sloshing… if lazy, park the car at an angle.
If more rain water enters, via the windows on either the driver or passenger side, than what can drain through the draining holes at the bottom of the doors, then the water collects inside the door at the bottom and eventually spill over and passes underneath this piece of plastic (which is supposed to cover the speaker hole in the door - behind the door pannel) Then the water enters the car from between the door pannel and the door. To test it open the door completely and let someone shower the window from the outside with a hose pipe for a 10 or more minutes, and check if water starts running out from underneath the door pannel at the bottom.
Good idea but we would hope that after seven years the OP would have got it fixed or got rid of the car by now. 
Useful info for anyone with a similar problem, though.
You are right about that.