Mexico City, Jan 22 (IANS/EFE): A team of geologists has discovered a large aquifer far beneath Mexico City that could supply potable water to the capital for many decades and serve as a reserve basin in times of drought, authorities said Monday.

"It's a deep aquifer of significant proportions, but they haven't been quantified yet and the next step is to carry out the necessary studies to see its real potential for sustainable extraction," Mexico City's water systems director, Ramon Aguirre, said in a radio interview.

Although news accounts have said the aquifer could supply the capital's water needs for a century, Aguirre did not confirm that estimate.

"That would be great," Aguirre said, adding that the water basin is an important discovery because it could provide emergency supplies during droughts.

"Even if there's more than 100 years of extractable water ... that doesn't mean it's enough to supply the city for more than 100 years. That difference needs to be pointed out," the official said.

He also noted that development of this new reserve will not affect other Mexico City aquifers or lead to sinkholes because clay layers separate one water basin from another.

Mexico City has been gradually sinking for centuries because water is drawn from underground aquifers faster than it can be replenished by rainfall and other natural sources.

Aguirre said exploration work began 18 months ago and that up to three more years of studies will be needed to determine the aquifer's yield capacity.

The project has an estimated price tag of as much as 500 million pesos ($39.3 million).