Why does water stay cool in a claypot even in peak summers?

Summers are here, and with them comes an endless thirst. We drink more water than usual and cold water feels almost magical in the heat.

Quick fun fact: when you drink cold water, it absorbs heat from your body as it warms up, helping lower your core temperature slightly. At the same time, temperature sensors in your mouth and throat send signals to the brain, creating an instant feeling of relief and freshness.

There are many ways to chill water. But one of the simplest and most fascinating — is the clay pot, or matka.

How does that humble, curvy vessel keep water cool without using a single unit of electricity?

What Is a clay pot made of?

A traditional clay pot is made from natural earthen clay, usually soil rich in fine mineral particles like silica and alumina.

The clay, often collected from riverbeds or alluvial soil, can be shaped easily when wet. After shaping, it is air-dried and then fired in a kiln, which hardens it.

Importantly, it is left unglazed. This means the surface is not sealed, and the pot remains slightly porous — full of microscopic holes invisible to the eye.

And those tiny pores are the key.

Everyday mystery

Look closely at a clay pot on a hot afternoon. Tiny droplets begin to appear on its outer surface. The sides feel slightly damp to the touch. Yet the water inside remains noticeably cooler than the surrounding air.

Is the pot leaking? Is it absorbing moisture from the outside? Or is something else happening entirely?

The answer lies in something your body already knows how to do.

The science: Evaporation

Evaporation is the process by which a liquid changes into vapour without boiling.

The microscopic pores in the clay allow small amounts of water to slowly seep to the outer surface of the pot. When this water comes into contact with warm air, it evaporates.

in schBut evaporation requires energy. To turn into vapour, the water must absorb heat, and it takes that heat from the water inside the pot. As a result, the remaining water becomes cooler.

In simple terms: when the water on the surface evaporates, it carries heat away with it.

If the pot were glazed (like ceramic plates), the pores would be sealed, no water would seep out, and cooling would not happen.

Why it works better in some places

Clay pots work best in hot, dry weather. In humid air, evaporation slows down because the air is already full of moisture .That is why matkas feel most effective in dry summer heat.

A smart and sustainable design

The rounded shape of the pot increases its surface area, allowing more evaporation. Air moving around it helps the cooling process. And it does all this without electricity, chemicals, or plastic. Long before refrigerators, people were using simple physics to stay cool.

In a world of machines and power consumption, the clay pot remains a quiet reminder that sometimes, the smartest technology is the simplest.