>Mexicans used to cool drinking water by storing it in a large unglazed ceramic container
They still do, especially out in the sticks where running water and electricity are still hard to come by. Also, many people still use them because they like the taste. I have one in my kitchen right now. Whenever anyone in my family goes to visit in Mexico and mine is broken, they bring me another. The flavor of the water is much like the smell of caliche after a rain. It is called "olla" but also can be called "cántaro". These were the jugs carried to the well or river for filling. I only saw a large one on a ranch near Big Bend National Park. Most household sized "cántaros" hold 1-1 and 1/2 gallons.
What you fashioned out of a canteen and a sock is known as a "cantina" or a "cantimplora", thus the americanized version, canteen. They are normally made from metal and covered with coarsely woven wool or heavy canvas. Unglazed clay is a much better medium for cooling. Compare tile roofs to metal roofs. Evaporative cooling only works well where the humidity is negligible.
