Getting fresh water to Peru's desert capital is no easy task.

Lima relies on a vast network of concrete tunnels to transport water originating in lakes in the Andes mountains to the bone-dry coastal city some 125 miles (200 kilometers) away.

By the time it arrives, it is so contaminated it must pass through four treatment plants that filter out potentially dangerous microorganisms.

Despite the complexities involved in keeping the taps flowing, authorities say water consumption in Lima ranks among the highest in the Andes region.

"There is no culture of conservation," said Yolanda Andia, a chemical engineer with state water company Sedapal. "It's pitiful."

In the richest parts of Lima, residents use 447 liters a day, nearly five times what is recommended by the World Health Organization. Overall, average daily usage is 250 liters for the city.

That compares with 168 in Colombia's capital, Bogota; 220 in Quito, Ecuador; and 200 in Santiago, Chile.

Authorities believe the high consumption stems partly from unawareness of the lengths officials must go to to ensure an abundant supply of clean water.

With a population of 9.1 million, Lima is the world's second-largest city located in desert terrain — second only to Cairo.

"Our work is hard," Andia said. "And even though in Lima it almost never rains, people don't know we get water from the lakes of the Andes."