It's also easy to wave a magical wand technological solution like desalination instead of looking into the issue more holistically: what is currently wasteful t

It's also easy to wave a magical wand technological solution like desalination instead of looking into the issue more holistically: what is currently wasteful that we could make more efficient? Desalination is just more waste of energy, it can be part of a solution but shouldn't be the solution. We really need to look into the natural systems we modified/interfered and figure out ways to be much more efficient with them. And that is what usually gets called "sustainable". It's not being a mennonite, much rather the opposite: be smarter about what we use, extract more from less.