It would have to be a lot more than that. As a rule, rain is produced by large lakes and seas, and some evaporation from tree cover. At a guess, I suppose Iran would get precipitation from the Gulf and Caspian, maybe the Mediterranean to a lesser extent, and some of their water renewal must be off snow melt.

I flew over Iran many years ago. Much of it reminded me of central Australia. Very arid and desolate, but beautiful from thousands of feet up.

My argument is not that said evaporation would make any sort of measurable improvement for Iran water situation, it is that it would not make it worse. I agree that there are local problems with water access, but that is a local concern, not a blank "AI/Datacentres bad" as it is being pushed right now.