Water is one of the most important substances on Earth. Every living being — plants, animals, and humans — needs water to survive.
Why is water important?
Our bodies are about 60–70% water. We need it to digest food, carry nutrients, remove waste, and stay healthy. Plants use water for photosynthesis. Animals drink water to live and cool their bodies.
Where do we find water?
Water is in oceans, rivers, lakes, ponds, and underground. It exists as ice in glaciers and as vapour in air. About 71% of Earth's surface has water, but most is salty ocean water. Only about 3% is fresh water — making clean drinking water very precious.
- 1.The Water Cycle:
- 2.Evaporation — Sun heats water; it turns into vapour and rises.
- 3.Condensation — Vapour cools and forms tiny droplets, making clouds.
- 4.Precipitation — Water falls as rain, snow, or hail.
- 5.Collection — Water gathers in rivers, lakes, and underground; the cycle repeats.
Puddles disappear on a hot day because the sun's heat evaporates the water into the air.
Water droplets form on a cold glass taken out of the fridge — warm air cools against the glass, and its water vapour condenses into liquid.
The Ganga is fed by glaciers in the Himalayas. Melting glacier water flows down into the river throughout the year.
Farmers dig wells to reach groundwater — rainwater that has slowly seeped through the soil over many years.
Wet clothes dry on a clothesline because water in the cloth evaporates into the air — the same process that dries puddles after rain.
How to save water: Close taps when not in use; fix leaks quickly; reuse wash water for plants; collect rainwater (rainwater harvesting).
Common mistakes
Many students think all Earth's water is drinkable. Most is salty sea water. Only a small fraction is fresh, so we must use it wisely and avoid waste.
Summary
Water is vital for all life. It cycles through evaporation, condensation, precipitation, and collection. Fresh water is limited — save it.