While this is true, we're not 100% out of the woods. My brother is an architect in the region and mentioned to me that our exurbs and suburbs are notorious for fudging their water sustainability numbers vs actual use.
Tripling would be 200% growth, quadrupling would be 300% growth. Therefore I wasn't sure which one you meant, and I checked: according to [1] there was roughly a tripling from 1.5M to 4.5M between 1980 and 2020.
[1] https://www.macrotrends.net/cities/23099/phoenix/population