Hi ALL, I've sent this post before re my Rover 214 GSi K Reg (boot spare wheel well full of water) but none of the possible causes posted have proved to be the problem! In the end, because I was getting so annoyed, I had my garage sort the leak. Well, the fault has been found.
To each side of the boot/tailgate are 2 vents behind each side of each rear wing hidden behind the bumper. These have a supposed "one-way" flap to let air out but they have both detiroated and let water in.
Remedy is to remove the bumper and sort the vents. At the moment the job is in progress as we have to wait for fine weather and for the boot etc to dry out from recent rain. Therefore the Rover is sat in the garage drying out and the job will be completed tomorrow, Friday. Fingers etc crossed. At the same time we are going to re-seal each rear lamp cluster just to make sure! Hope this info helpful to members who's boot spare wheel well fills with water.
I'll send a further post when jobs done. Have fun, David W

That reminds me I must check mine . I've read up on this before and it seems the vents in the three quarter panel and the tail lights are the common causes .

My 100 suffered from some terrible leaks, the foam sound deadening didn't help! Musky , that's all that needs to be said really.

Hi, well the Rover back from garage and appears to be sound and dry in the boot. I am giving it a good airing to make sure its dry then try and get rid of that musty smell! Might clean the whole boot area with "gunk" on a cloth then wipe clean. The smell of the Gunk is a nice, clean and agricultrue smell which should get rid of the smell then a good spray of Febreeze! I think we've cracked the "leaking boot" problem. Cheers, David W

yeah i had a small puddle of water in a dip in the boot. looked like the leak was coming from the light cluster vents. i used some interior shampoo made for upholstry but does lots of other stuuf too. its now dry and no corrosion what so ever in the boot!!!