Has anyone had problems with water collecting under the driver's side of the vehicle? Water in footwell, water under driver's seat, water under rear seat ... Any tips?

A quick search of the forum would find that the most likely source is a disconnected air conditioner drain.

There are lots of threads in forum on subject.

Searching for Drain gives these
https://www.freel2.com/forum/search.php?se...rch_time=0

These is about the aircon drain;
https://www.freel2.com/forum/topic39336.html?highlight=drain
https://www.freel2.com/forum/topic39219.html?highlight=drain

Sunroof Drain;
https://www.freel2.com/forum/topic26799.html?highlight=drain

From under bonnet
https://www.freel2.com/forum/topic36275.html?highlight=drain

and so forth---- FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Add door seals to the list... that'll dump water inside if it's raining.

Also the seal around where the steering wheel goes through the floor - road water splashing up.

Is it happening only when it rains? That should narrow the search down to aircon vs ingress.

Grue - thank you for your suggestions. I think the problem has been solved as on inspection the drainage tube from the sunroof on the driver's side had become detached. This was suggested by another member and since my garage replaced the drainage tube no further water seems to be entering the car. Now the long job of drying out is in progress!

Thank you Suzyjax for letting us know the solution, it will help forum members in the future. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)