Whenever it rains heavily, water will always collect on the inside of my doors - usually the front passenger doors are the worst, but I've seen it whenever I have opened all of them.

The water seems to collect where the bottom of the door closes on the body of the car (I hope this makes sense). Whenever I open the door after heavy rain, there's a huge rush of water that spills out on to the side steps. No water seems to be actually getting inside the vehicle or in the foot wells, so I'm not 100% panicking about it just yet.

Is this a normal RRS quirk or is there something else I should be getting looked at here?

Have you got a sunroof?
Check the drain holes - prone to corroding

I think initially I think I would check the condition of the rubber seal on the door (not the body one) as I think they are only stuck on with 3m tape, in case water is leaking in at the top and running down between the door and body seal and collecting at the bottom as they are still sealing at the bottom ok. but when you open the door it releases the trapped water, Only a suggestion. Not sure it would be sunroof drains if you have one, as they are actually inside the car and come out under the front wing.

Cheers
Col

the rubber seal on the doors need to be looked at had the same on my work van found a slight slit it the side of the seal little bit of mastic and it seems to have solved it