It would require a lot of expansion for the required volume.
A barrel of oil has about 159 litres in it. The Keystone Pipeline would have transported 1.1 million barrels if it were fully expanded. 174,900,000 million litres per day. The City of Phoenix by itself uses about 1 billion litres per day.
I was going to say "but that probably double-counts recycled water" and then I looked it up and recycled water is only 8% of Phoenix's water usage, and it's 10% nationally in the US.