Comment by blurker

It's surprisingly difficult to separate salt from water to the point that it's drinkable. That difficulty translates to it being very costly and that cost is so prohibitive that most places will choose another option. Like even building massive pipelines to transport water across 1000's of kilometers is probably going to be a better option. It's pretty much always going to be more economical to use the water that the earth is naturally desalinating for us.