> bad decisions from the last 50

Some of these "bad decisions" are ignoring the old systems, and ways. The hubris of "modernization" as better.

The water systems of old Iran are fascinating, and well covered if you hunt around for the info. https://en.wikipedia.org/wiki/Qanat

Old techniques like Qanats and Shabestans aren't going to help Iranians deal with effluents in the water, or straight-up water misuse by businesses controlled by the Ayatollahs.