Wally I look at these shanty towns and two questions occur. One, where do you crap? Two, where do you find clean water to drink?
Historically the problem of cities was that they were the home of disease. This was powered by the problem of contaminated water. So what happens is you shit in a pit latrine, the bacterial and amoebic pathogens, get into the ground water. Every one drinks from wells which draw on this water, and you have a population with a systemic problem they can only avoid by running away from it. Refusing to drink unboiled water can help, but diseases can be contracted from the hygiene necessary for a decent life.
So many countries have problems on this front. To the extent that the US has clean water and adequate sanitation and good treatment of domestic and industrial effluent we are great.
In New Jersey where I live the water, the ground water, is polluted. It is polluted with salt, and to a lesser extent with fertilizer. There is also the problem of pollutants produced by industry. On the whole there is a sufficient amount of clean water for everyone. This is not to say that there are not problems. In the US we expect that there should be water for all our needs. When we have honest discussions informed by individuals with expertise then we are great. When we respond to problems by refusing to acknowledge that they exist then we are pathetic.
Detroit's trouble on this front come to mind. The unsustainable use of aquifers for agriculture in the great plains is also an issue.
Problems like Detroit are fixable. Problems like the Ogallala Aquifer are why we are a mess. No solutions are on the table. Politicians are silent. Show of hands, anyone in the room ever hear the word Ogallala before?
End of the day, writing this is a waste of time. Reading it - even more so.