Water mains blowing up is a regular occurrence in the States and guess what you can shut them off. If you think that a single water main or even a group of mains caused this dramatic crisis then you are ignoring what Irans government is not only saying as of now but for years. You cant blame this on a single incident even the the Supreme Leader has been saying they are facing this threat since 2011. Also what about the second most populous city? Its at dead water level already. 

Israel blew up the main waterlines.
A flood when there is the worst drought in 60years tells you everything you need to know. A lot of water was lost.

openyoureyes

Politics_And_Law

Tehran May Be Evacuated as Iran Faces Worst Drought in Decades

Cje95

Lol that hit pipelines sure but that's what happens in war. They still have no water in their reservoirs and haven't had any rain this year. Israel didn't strike the dams or the surrounding infrastructure. That "flood" was located to a very small section of the city. It wasnt like the whole city went underwater. 