A glass of water from the freezer can never beat the satisfaction of drinking water from an earthen pot. We Indians especially believe in this statement, which even I feel is very true.
The water inside the clay pot is cool due to the evaporation process. The clay pot has tiny pores in the surface and water gets evaporated very quickly through these pores. Due to this evaporation process, the heat of the water inside the pot is lost, which lowers the temperature of the water. This is how we get cool water from the earthen pot which is just at the right temperature during any season throughout the year.