OK, I admit it. I get sucked into some of those stupid click-bait articles. This pic was in the one I traversed this morning. No explanation accompanied it. Any guesses as to what happened? I have one, but I'll forgo the spoiler.
There is a hose in water that seems to be connected to a tap. Maybe something wrong with the tap or where its connected to, and the water was syphoned out of the pool?
EDIT: Maybe they wanted to fill water into the pool, and were watering the yard from another tap at the same time that drew a lot more water and created a water jet pump effect that drained the pool and added the pool water to the other tap watering the yard?