When we lived in Mesa Az there was a water treatment facility just outside our 'hood. Had a buddy living with us that worked for the Central AZ Project. Pretty much supplies all the water to AZ.
We lived in Tucson when they decided to put part of Tucson on CAP water - within a couple of months, everybody's plumbing was leaking - the chemistry in that water was different than what the old galvanized pipes were clogged with, and it fubar'd the pipes/joints and everybody started leaking - plus it tasted and smelled bad. They ended up deciding to pump the CAP water down to recharge the aquifer and keep everyone on the aquifer instead.
