Zeer Pots are reasonable off-grid refrigeration solutions when the power goes out for the long haul. Granted, this isn't ideal for foods that have a high propensity to develop bacteria (meats, eggs, etc.) However, in a pinch, you can use this method to keep foods somewhat cold and it sure beats rolling the dice with potentially deadly food poisoning.
Also, Zeer pots must be used in dry, hot climates in order to work effectively. Make sure you check the temperature of your foods often to ensure food safety. Food poisoning is nothing to play around with.
The pot-in-pot or Zeer pot has been in use for thousands of years dating back to ancient Egyptian times (2,500 BC). It made a comeback in 1990 to help address famine and poverty as a result of food rotting before it could be eaten in Africa.
Practical Uses & Directions
A Zeer pot is ideal for produce and fruits. You might also get away with some dairy products that you make for yourself (such as making a half gallon of powdered milk or homemade butter). The clay pots I used to take these pictures are obviously way too small (that is a wild strawberry, by the way). You can pick up bigger clay pots just about anywhere that sells gardening supplies.
The trick to making a Zeer pot work is to keep the sand and towel moist. The moisture is what pulls the heat from the center and pushes it outward. The Zeer pot must be used in a dry climate or the evaporation of water won't happen (which is how it cools the center of the inner clay pot).
Supplies you’ll need:
2 clay pots (1 smaller than the other)
Put enough sand in the larger pot to line the bottom.
Place the smaller pot inside the bigger pot.
Fill the gap between larger and smaller pots with sand.
Wet the sand and cover it with a wet towel.
The water in the sand will evaporate and remove the heat from the larger pot.
This also makes for a good science project for school by demonstrating exothermic activity. :)