Mumbai has no fresh water supply of its own to write about... very little. It is Maharashtra water that the migrants are using. No amount of work generates new fresh water supplies - what the state has thats it!
So if half of India pours into Maharashtra based on the filthy claim that anyone can live anywhere - where does Maharashtra find the water for all these people?
It is easy to write idealistic nonsense on a piece of paper - it is hard to see the hardships that a great state like Mahasrashtra is bearing resolutely.