Hahaha super cool idea mate but unfortunately the fog challenged my spotting skills a bit BUT:
I played it back with half speed and I think you missed the theft all the time: it is a big white snake laying in your pool even in daylight! There on the left ;)
The music was super nice! Even on 0,5 speed it is sooo moody.
Thanks for sharing this little experiment and "your welcome" for me spotting the water theft. Haha
HAHAHAHA...He's our resident pool snake - He eats a lot of leaves that fall in (& for all we know - maybe the odd possum here and there?) LOL