The reek of unwashed toilets spilled into the street in the neighborhood of unpainted cinder block houses. Out on the main road, hundreds of residents banged plastic buckets and blocked the path of irate drivers while children scoured the surrounding area for government trucks. Finally, the impatient crowd launched into a high-pitched chant, repeating one word at fever pitch: "Water, Water, Water!"  About five million people, or a quarter of the population of Mexico City's urban sprawl, woke up Thursday with dry taps. The drought was caused by the biggest stoppage in the city's main reservoir system in recent years to ration its depleting supplies. Government officials hope this and four other stoppages will keep water flowing until the summer rainy season fills the basins back up. But they warn that the Mexican capital needs to seriously overhaul its water system to stop an unfathomable disaster in the future. (See pictures of the world water crisis.)  It is perhaps unsurprising that the biggest metropolis in the Western hemisphere is confronting problems with its water supply  and becoming an alarming cautionary tale for other megacities. Scientists have been talking for years about how humans are pumping up too much water while ripping apart too many forests, and warning that the vital liquid could become the next commodity nations are fighting over with tanks and bombers. But it is hard for most people to appreciate quite how valuable a simple thing like water is  until the taps turn off. (See pictures of the contentious politics of water in Central Asia.)  Housewife Graciela Martinez, 44, complains that the smell of her bathroom  used by her family of eight  had forced them all outside. "We have got no toilets, I can't wash my children, I can't cook, I can't clean the mess off the floor," Martinez says, trying to find shade from the sweltering sun. "And the worst thing is, we have got almost nothing to drink."  Paradoxically, the thirsty city was once a great lake, where the Aztecs founded their island citadel Tenochtitlan in 1325. When the Spanish conquerors took control they drained much of the water, laying the basis for the vast expansion of the metropolis across the entire Valley of Mexico. However, as the growing population continues to suck water out in wells, Mexico City is sinking down into the old lake bed at a rate of about three inches a year. This downward plunge puts extra pressure on water distribution pipes, which are now so leaky they lose about 40% of liquid before it even reaches homes.  With its own supplies evaporating, Mexico City relies on the Cutzamala system, a network of reservoirs and treatment plants that pump in water from hundreds of miles around. However, this year Cutzamala itself is running dry amid low levels of rainfall in the area. Its main basin is only 47% full, compared to an annual average of 70% for early April. "This could be caused by climate change and deforestation. These are difficult factors to understand and predict," says Felipe Arreguin, under director of the National Water Commission. "We had to have the stoppages now to make sure that some supply can continue until the rain in June." The first two partial stoppages in February and March cut off water to hundreds of thousands. In the April action, the entire Cutzamala system will be shut down for 36 hours, before gradually resuming water pumping over several days.  Martinez is particularly anxious because this means there will be no water in her taps this entire weekend. She is also enraged that the blight is mostly hitting poor neighborhoods like hers. "The rich are still swimming in their pools while we are dying of thirst," she says. Playing up to the class war theme, Mexican newspaper Reforma showed a photo of a woman using a public tap in a poor area next to another woman hosing down her lawn in a rich suburb. (See pictures of crime fighting in Mexico City.)  Ramon Aguirre, director of Mexico City's water department, says the government has tried to distribute supplies as fairly as possible but the Cutzamala system is hooked up to many of the unplanned communities on the city outskirts. The city has, however, sent out of fleets of water trucks, and Mayor Marcelo Ebrard  who built urban beaches and a winter ice rink for the poor  is personally handing out free bottled water. Aguirre says the long-term solution involves teaching people to ration their water much better. "We need to educate people from when they are children that water is valuable and needs to be used wisely," he says.  Few Mexico City residents currently heed such advice. Keen on long showers and washing their cars, homes and clothes well, the average Mexico City resident uses 300 liters of waters per day compared to 180 per day in some European cities, says Arreguin. Furthermore, on Easter Saturdays, residents traditionally have huge water fights, in which everyone from grandparents to young children join in hurling bucket loads over each other. Piet Klop, an investigator at the Washington-based environmental think tank World Resources Institute, says that people will not learn to ration water unless it hits their pockets. "We need to understand that it is a more valuable commodity than oil and prices must reflect that better," Klop says. "Cheap subsidized water is not helping people. It is giving them a bad service." However, radically hiking the prices of any basic commodity would be a tough sell for any politician, especially in a turbulent democracy such as Mexico.
Faced with a collapsing delivery system and the likely effects of global warming, the hemisphere's largest city turns off the tap to try to save water