No Coolant + Wet floor = ?

[timxxv]

I haven't started the LR (D1) for about ten days or so and it's been stored in the garage, so I was surprised to find puddles on either side of the front wheel well (the carpets are removed so steel floor only). I checked the reservoir and it was entirely empty.

Am I looking at a leaky heater? bearing in mind it had to empty the coolant reservoir without the motor running.

I'm aware this is a real PITA, but 100 times better than a leaky head gasket as a culprit for my coolant loss.

Is it possible? I can't imagine any other source for the water unless rain had just taken a few days to leak through from where it was gathered.