They usually settled outside the city walls.
Answer: Macuahuitl
Explanation: The blades of the Aztecs swords, made of obsidian, were sharper than steel. They could behead a horse. The Aztecs called their obsidian-edged sword macuahuitl.
They can boil old nasty "gray water", or they can make a desalinator and remove the salt which works kinda like a moonshine still by boiling the water and then cooling the steam down and out the other end comes fresh water, or they can catch rain water.
