using earthen pitcher can coll water? give reason?

Answer 1

Earthenware containers that are unglazed allow water to slowly seep through to the outside surface. The water evaporates and cools down the container. This is an effect which was well known to the people of the American Southwest and Mexico. In the old days before refrigeration they often hung large earthenware water containers in the shade of large trees where they could provide a cool drink.

Answer 2

If the pitcher is slightly porous. the water will receive evaporative cooling.