Rio Tinto and BHP Billiton have both approved more than a billion dollars for the construction of a new seawater desalination facility for the Escondida copper mine.
BHP will provide US$1.927 billion while Rio has given the go-ahead for an investment of US$ 1.03 billion.
Rio said it will fund its investment through the company's share of Escondida's cash flows.
The project will see the construction of a 2500 litre per second plant at the mine, which will ensure a sustainable supply of water for the 152 000 tonne per day OGP1 copper concentrator.
Construction will begin this month and include the development of two pipelines, four high pressure pump stations, a reservoir at the mine, and high voltage infrastructure.
It will be commissioned in 2017.
Peter Beavan, BHP's copper chief, said "securing a sustainable water supply in the Atacama Desert is a major priority for all Chilean copper producers, so the approval of the Escondida Watetr Supply project is a significant milestone for our business".
"The new desalination facility will minimise our reliance on the region's aquifers, which will help us to meet our environment commitments and enable us to achieve our long-term business strategy."
Copper has been pegged as the base metal of the future, with more investment in major copper mining projects likely in the coming years.