That's exactly the point. Where do you think water comes from? You can't just build a city in the middle of the desert. In order for it to be sustainable you ne

That's exactly the point. Where do you think water comes from? You can't just build a city in the middle of the desert. In order for it to be sustainable you need it located next to a lake or river or other large source of freshwater that's easily exploited. Water is a natural resource just like any other.