Endless mountains tower over the arid Permian Basin. Mountains almost a mile high. Mountains of water.

A football field covered with a foot of water is about an acre foot, a standard measure of water reservoir capacity. A mountain of water on that field 4,600 ft high represents the volume of produced water that could be coming out of the Permian Basin every day once oil production reaches its peak in the next few years.

Oil production could reach 6 MMbbl/d. Water cuts average 4 bbl to 8 bbl per barrel of oil. That is 1.5 billion gallons of water, or 4,600 acre feet, every day—and that is just the Permian.