How Cities Save Water

L.A.’s use of floating shade balls (above), which block the sun over reservoirs to prevent evaporation, is just one of many inventive new methods being tapped globally to prevent shortages.

REVIVING ANCIENT AQUEDUCTS

Over the past several years, a Peruvian utility company has revived pre-Inca aqueducts to route water from the Andes Mountains into cities.

RATIONING CONSUMPTION

Earlier this year, Puerto Rican authorities placed more than 150,000 residents on a 24-hours-on, 48-hours-off water schedule. The savings helped slightly.

WIRING BILLBOARDS

Officials in Australia encourage conservation by showing water reservoir levels to would-be consumers in real time. Research shows the campaign helped cut consumption in half.