At least two million residents of Mexico City are without water after authorities cut off
supplies following a record drop in water reserves.

The two-day shutdown of a main pipeline began late on Thursday, in time for the Easter holiday weekend, when many residents are out of town.

The move is part of a five-month emergency rationing plan announced by Mexican authorities in January.

The city's Cutzamala supply system is at 47 per cent capacity, its lowest ever level
because of low rainfall in 2008, Conagua, Mexico's national water commission said.

Leak concerns

The commission also plans to make repairs to stop leaks in the distribution network of one of the main water supply systems.

"Losses from leaks are greater than the total resources supplied through this system," Conagua's website said.

The city's government said it would provide 500 trucks with water tanks and purified water containers in areas worst hit by the cuts.

The government said it hopes to restore 50 per cent of the service by late on Saturday and return to a full service by Wednesday.