We have to. Arizona is at the bottom of the water rights agreement among the states drawing from the Colorado River. I see a lot of water harvesting structures here, often in the form of parks and greenways.
Edit: Just looked it up and california gets about 5 million acre feet (maf), AZ gets about 2.8maf and Nevada only gets 0.3maf.
So per capita, AZ is doing pretty well allocation-wise.
When there is not enough water, priority goes to those holding senior water rights.
(Complicating this is that various tribal nations have water rights senior to the states, and it is only now affecting allocations)
And we're back down to 1950s level of water usage due to less agriculture. Other parts of AZ don't have that reduction in usage, and have to try to do more with less
The Intel fab facility does a lot to reclaim water, ultimately pumping used water back into the aquifer. New construction, such as the light rail expansion has purposely-designed swales to also help with that.
If anything, it’s because the ground water has been banked for years that it is mitigating the water restriction in effect in AZ last year.
On the other hand, we have so much precipitation this past winter, that the dams along the Salt River are having daily releases now. If you’re living in Phoenix right now, you might notice the elevated humidity for this time of the year; we might have a monsoon season starting weeks early here.