Botijo cooling

Botijo Water Cooling

The earthen walls of the botijo absorb part of the water contained in the jug. The water reaches the surface, where it slowly evaporates. Water evaporation requires energy. Part of this energy is extracted from the water jug, resulting in the cooling of the water within. The amount of cooling depends on many factors, such as the shape of the botijo, the material of which it is made, the amount of water within, the outside temperature, the humidity, etc. Under good conditions, a cooling of about 10 degrees Celsius is achievable.

Similar cooling methods

You can observe the same water cooling effect of a botijo on a canteen with lined cover. If you submerge the canteen in water so that the cover absorbs the water, and then leave the canteen outdoors until the cover dries up, the water inside the canteen will have cooled.

You can also observe this effect by placing a regular water bottle inside a tick sock. Soak the sock and place the bottle outside until the sock is dry. The water in the bottle will have cooled.

Food Preservation

In the year 2000 a Nigerian teacher was awarded the Rolex Award for Enterprise for his utilization of the water evaporation cooling system to implement a food preservation system for dry climates.

His implementation consists of two earthenware pots of different sizes, placed one inside the other. The space between the pots is filled with wet sand, and food is placed in the inner pot. The evaporation of the water in the sand between the pots cools the inner pot, using the same effect used in a botijo. By keeping the sand moist, the food in the inner pot is kept cool.

You can read a full description of this cooling device here.