Earlier in the year, I noticed a damp smell and a lot of water in the rear passenger footwell. Initially, I thought one of the kids had spilled their water bottle; however, it was a lot more water. I vacuumed out the water and asked my mechanic what he thought was the problem. The mechanic sent me to an aircon guy, the aircon guy sent me to a sunroof guy. The sunroof guy cleaned the drains and said all is good. So relieved, I took the car for a weekend to JHB. The car stood outside overnight, and there was a thunderstorm and much to my horror, the rear footwells were soaked again inthe morning
A bit annoyed from going from pillar to post, I decided to take things into my own, inexperienced, hands. Did a bit of research and experimentation and found that the problem was the "yellow grommet of doom". A pretty well known design flaw on f10's that occur when the windscreen drains get blocked.
The best guide I found was this:
So I undertook it myself, and managed to fix it!
water leaking through passenger firewall area
waterline
old grommet
cleaned drain lines

Cleaned area and replaced with new grommet

made cuts in seal of the cover to allow drainage if drain lines get blocked again
I then had to lift the carpet and sound proofing to vacuum and air dry the area. And for the last 6 months or so, no leaks and no smell at all.