How to Conserve Water While Facing Down a Megadrought

In the rolling hills around San Diego and its suburbs, the rumble of bulldozers and the whine of power saws fill the air as a slew of new homes and apartments rise up. The region is booming, its population growing at a rate of about 1 percent a year.

This, in spite of the fact that Southern California, along with much of the West, is in the midst of what experts call a megadrought that some believe may not be a temporary, one-off occurrence, but a recurring event or even a climate...