There's no mention of "cheap" or "cheaper" in that article. None. I tend to agree that's what they meant, but I for one resent that it's not spelled out/ it's implied. The _cause_ is lower price, it's not source of the product. Is it lower price because it's imported? Sure, probably. But damn it, spell it out - you can even make something interesting out of it (chart consumption vs price, dunno). And let me tell you - I'm not even convinced they got the causality right, even _if_ that's what they meant. It's basically a meme that boomers were telling young people that they're poor because they eat avocado toast - which implies that it got popular (in a niche) before it got cheap. Sure, there's a positive feedback loop in there (more interest -> more import -> economies of scale -> lower prices -> even more interest), but I think they missed the "why".
> the average water use would go up "because" it was coming from someplace other than your village's small oasis
No, absolutely not. It would go up, in your example, because it was more readily available. The source has nothing to do with it except indirectly - the availability has everything to do with it.