Everything to do with Las Vegas’s water supply and disposal is watched, measured and checked. 40% of the water is recycled for indoor use. Every drop is monitored acoustically to detect possible leaks within 6,500 miles of pipes.

In addition to a complex and visionary system of recycling wastewater, Southern Nevada’s conservation efforts have generated a keen public awareness, and spawned hands-on programs in the public schools to teach about food-growing and water use in the desert.

* Picture of ghost city St Thomas at the bottom of drought-ridden Lake Mead.