Hitting desalination plant will mostly (and almost only) hurt the population outside of IRGC power circle, exactly the population the USA incited to rebel for a few years, with pakistani help. Basically South Alborz. Iran did have a water crisis, but it was agricultural water that made them have to import more food, not an issue of drinking water. The only way to truly start a global Iranian famine (what a terrible weapon tbh, i can't help but to think less of people who think about using it, it's impossible for me to stay neutral,it is an inhumane stance, and i would be ashamed of having it) is to block Iran northern trading routes to Russia/Kazakhstan/Azerbaijan, which, to be clear, is impossible.

Ah yes the true and tried strategy of civilian bombing, worked so well for: the nazis bombing campaign against the UK.

Same goes with Russia against Ukraine.

Iran depends on desalination for around 3% of its drinking water, and has said that any such attacks on its infrastructure will see the same to any country that has support the USA/Israel military actions.

USA allies in the region will be largely uninhabitable, since they depend on power and desalination for their existence.

Still, maybe that is what Trump, the crazy bastard, wants.

Assuming that USA would succeed to do such a destruction, their "peace keepers" would never have enough rations to feed so many people as they are in Iran.

The only way for USA to succeed would be to attempt to kill most of the Iranians, which would only make even more clear that USA are not the "good guys" and they have lost long ago the moral authority to demand anything from others in international relationships.