Water leak

[kurgan]

I've got a 2000 A4 Avant Diesel (right hand drive). Over the last two weeks I've been having trouble with a water leak into the footwell of the driver side passenger and to a lesser extent the driver footwell. We've been having heavy rain over the last few days and each day I've had to bail out 1-2 inches of water from the rear footwell. Everything else in the car is bone dry, including the door seals. I've read some similar threads in the forum and I do have a sun roof but I've also had a look under the hood and there was a lot of water around the brake fluid container to the battery housing. I just siphoned what must be several litres out of there (and got a mouthful of stale rain water and engine dirt for my trouble!) and I think this must be the source of the leak.
One of the threads mentioned blocked drain plugs, where exactly are these and is it in any way realistic for me to clean them myself? If not and that is the problem is it likely to be an expensive job?
Many thanks!
Ed

[lordoftherings]

it sounds like your drain plugs are clogged, check under your battery next to the firewall for these plugs

[kurgan]

Thanks I'll have a go at that tomorrow