It's a very interesting idea - but practically speaking, the kind of water volumes needed for drinking and bathing water for a city like Las Vegas are dwarfed by the volumes needed for the farming of sugar beets, alfalfa for dairy, golf course grass maintenance, etc. If current trends in the American Southwest continue, extreme water conservation will have to become the norm (the other alternative being depopulation of the region).
Yeah we can't realistically get better water outcomes by only changing out supply. We have to change our usage too. Farms should be converting to crops that have lower water usage, and food manufacturers should be converting to foods that make use of those crops.
