How is that possible, due to evaporation?

Elimiating lawns is a great idea, seeing as they live in a massive desert. I approve of that, for everyone who cares.

the famed fountains at the Bellagio Hotel use water from a private well — not the Colorado River. He also said the water that evaporates into the hot desert air is replaced with recycled water from a 1.5 million gallon pool.

so… they just drain groundwater?