We seem to have one of these water arguments on SSP at least once a year, and as usual, no one seems to really grasp that:
1. There is a huge problem with too much water being used in the southwest
2. This has almost nothing to do with the population of residents increasing, and everything to do with water rights for agriculture negotiated a century ago
I can't seem to find it now, but there is the oft-posted study (don B probably has it filed away somewhere

) showing that in the 90's and 00's when Phoenix was growing at its highest rate, aggregate water use in the metro area was actually DROPPING, as most of the new housing was replacing agricultural land (the real water hog). An acre of housing, at almost any density, uses less water than an acre of lettuce or cotton. And yes, it's absolutely absurd that a water-intensive crop like cotton is grown in Arizona, but that's due to water rights negotiated a century ago never being altered, not because of air conditioning or people moving to the desert to live.