Question

Why do we keep water in earthen pots during summer?

Answer 1

This makes the water cool.
In an earthen pot, water gets evaporated quickly through the pores. Cooling is caused by evaporation. Some heat energy is utilised during the process of evaporation. Since this energy is taken from the water itself, it leads to a lowering of temperature in the remaining amount of water. But in metal or glass containers, there are no pores and, because of that, the rate of evaporation in quite low, producing only a slight fall in temperature.