If you look at the top 10 cities, all of them have a river, except Mexico City. That’s the real outlier. Large cities require lots of water, and that city is a really weird exception.
Tenochtitlan was a “floating city”, with artificial islands created on top of Lake Texcoco. Mexico City was founded on top of the ruins of the old Aztec capital and the lake was mostly drained.
To overcome the problems of drinking water, the Aztecs built a system of dams to separate the salty waters of the lake from the rain water of the effluents.
Las Vegas being the exception that kind of proves the rule.
A city that’s barely a hundred years old isn’t really relevant when talking about history of the human race predating the invention of bottles.
Earliest glass bottles are thought to be from 1500 BC according to https://en.wikipedia.org/wiki/Glass_bottle. Even plastic bottles might be twice as old as Vegas according to https://en.wikipedia.org/wiki/Timeline_of_plastic_development but that depends on definition of plastic.
If you look at the top 10 cities, all of them have a river, except Mexico City. That’s the real outlier. Large cities require lots of water, and that city is a really weird exception.
Tenochtitlan was a “floating city”, with artificial islands created on top of Lake Texcoco. Mexico City was founded on top of the ruins of the old Aztec capital and the lake was mostly drained.
So, essentially they’ve been relying on rain water since day one.
https://en.m.wikipedia.org/wiki/Las_Vegas_Wash