Baja California is not that similar to Mexico City, but I will just mention that when I lived in Tijuana and Ensenada for a few years, the water being shut off

Baja California is not that similar to Mexico City, but I will just mention that when I lived in Tijuana and Ensenada for a few years, the water being shut off for a few days or even a week at a time during the summer was fairly common. Many businesses or well-off families have backup water tanks. But I never saw a point where there wasn't normal bottled or reverse-osmosis water available to buy in stores. And in northern Baja, although it is semi-arid, the weather is not nearly as variable and the population is minuscule in comparison. I'm just remembering the times when I had refilled water jugs stockpiled in the bathroom for flushing the toilet. If things get really bad in Mexico City, who knows, but there might be millions of people doing that sort of thing for a month. And then if it gets to the point where you really can't flush your toilet or get water to drink, times a million people (supposing only a fraction of the 22 million are really cut off for a significant amount of time), times a month, people will get desperate and probably resort to doing things they normally wouldn't in order to survive. It sounds apocalyptic to me.