Water is heavy, and almost none of the water used in the world is used for human consumption. It will never make more economic sense to ship water long distances than to move the economic activities that require it to the source of the water. This is leaving aside the subject of aqueducts, but there's really only so long you can make an aqueduct, and most countries border countries in roughly similar economic situations. Siphoning water from "poorer countries" via aqueducts is not going to be a thing.