Water usage per pound of copper varies from 5.4 gallons per pound of Cu for Morenci mine, to 62.3 gallons for Morenci. Interestingly, from a little reading at Freeport-McMoRan's web site Miami does heap leaching of old material, but mostly seems to process ore from nearby Morenci. Both mines produce a mixture of oxide and sulfide. Then it might be a question of accounting how you allocate water use to the Cu produced by these two mines.

Asarco's Silver Bell, which uses 6.7 gallons per pound Cu, might be closest to our case. Half their ore is drilled, blasted, and leached in place, while the other half is transported to a leaching dump. I don't think leaching will work on sulfides, so they must be mining Cu oxide.

Silver Bell produces 67 tons of Cu a day, so they must use about 1,000,000 gallons of water a day.