Water

Drying wet clothes is the activity that does not involve use of water. Drying does not require water as water make things wet. To dry wet clothes, we hand them in open where the heat from the sun and air dries them. Washing clothes, bathing and cleaning utensils are the activities that involve use of water.

For brushing our teeth we require only a mug of water to wash our mouth after we brush our teeth. Whereas, activities like bathing, washing clothes and mopping a room require more a bucket of water or even more.

Water is used in industries to produce almost all things we use. It takes two glasses of water to produce one page of our book. So, if we waste a page of our book or copy by misusing it, we actually waste 2 glasses of water.

We get water from taps in our home. This tap water is drawn either from a river, lake or well and is then supplied through a network of pipes to the tap in our homes.

Evaporation will be the slowest in a glass of water kept in a room because it is kept under shade and it does not receive direct sunlight. Though during daytime all the surrounding of a room get heated up, so the warm air provides heat for evaporation of water in the room but it occurs at the slowest speed. A tray of water, kept in sunlight, a kettle of water kept on a burner and a bucket of water kept on rooftop get evaporated more quickly because they receive heat directly from sunlight and burner.

Transpiration is a process in which plants release water vapor. A part of water that plants get is used to prepare their food and store in different parts of the plant. The remaining amount of water is released by plants in the form of water vapor in air. This process of releasing water vapor by plants into the air is called transpiration.

When we move above the surface of earth towards higher altitudes it gets cold. The air when it moves up also becomes cool. At a great height the air becomes so cold that the water vapor in it start to condense and form tiny droplets which float in the air and appear to us as clouds.

When it rains, the water fills up the lakes and ponds. Some water gets absorbed by the soil and ground and the remaining water penetrates the ground which adds to the ground water level. This ground water becomes the source of water for wells. So, wells are fed by ground water.

Excess of rainfall continues to add more and more water to rivers, lakes and ponds thus leading to a rise in in their level of water. When the water level rises, the water flows onto the land thus causing floods. The land, property, crop fields everything gets immersed thereby bringing great damage to them. Animals too get carried away with the risen water level. They get trapped in the water and are unable to find a way out, thus they remain trapped and often die when the flood water withdraws.

Catch water where it falls is the basic idea behind rain water harvesting. So, to increase the availability of water, water is collected wherever it falls and is stored for using it later. Rooftop rainwater harvesting is one such way where the rainwater is collected into storage tanks from rooftop through pipes.

Activities where water is being used in the above figure are-

a. Bathing

b. Washing clothes

c. Lifting water from the well to store for use and for drinking in the earthen pot.

Two activities that require more than a bucket of water are

a. Irrigating the crop fields.

b. Washing clothes.

Two activities that require less than one bucket of water are-

a. Brushing teeth

b. Producing one page of a book

Wet clothes placed on a clothes line get dry after some time because water disappears from them as they dry up from the heat of the sun. Water has salt dissolved in it so on receiving heat water evaporates into vapor leaving behind salt. Thus, water changes into water vapor and the clothes dry up. This water vapor mixes with the air and is invisible.

Water kept in sunlight gets direct heat from the sun and thus it gets evaporated. But water kept under the shade of tree also gets evaporated even though it is under shade and does not receive direct sunlight. This is because during daytime all the air surrounding the tree also get heated up, so the warm air provides heat for evaporation of water kept under the shade of a tree but it occurs very slowly.

The areas that are covered with concrete lower the availability of ground water because such areas reduce the seepage (entry) of rainwater into the ground thereby affecting the availability of ground water.

There is a need to conserve water because of the following reasons-

a. When the ground water level decreases, the amount of water on earth remains the same but the amount that is available for use to use is very limited because fallen level of ground water means that water cannot be used. So, water should be conserved in order to increase the ground water level and also to fulfil the shortage of water when underground water level goes down drastically.

b. There is a continuous increase in the population with which the demand of water for use is also increasing. With more people and same amount of water on the planet, there will come a time when the world will have shortage of water. So, water should be conserved for a sustainable future where the coming generations do not have to face shortage of water.

Water, as goes into atmosphere by the processes of evaporation and _transpiration and forms clouds, which on condensation fall in the form of rain and snow.

Water from water bodies evaporates on getting heated. Plants also transpire water from their leaves, known as transpiration. The air at high altitudes is so cold that the water vapor condenses and forms tiny droplets of water which appear to us as clouds. When the clouds cannot hold any more water, it falls down on the surface of earth in the form of rain and in form of snow at places that have very cold temperature.

Most of the water that falls on the land as rain and snow, sooner or later goes back to a sea or an ocean. This happens in the following manner- When the snow on the mountains melt due to sun’s heat, the water flows down from the mountain in the form of rivers and streams. These river (that also receive rain water directly) travel long distances and ultimately end up joining a sea or an ocean. So, ultimately the water that evaporates from sea or an ocean is added back to them.

To get salt back from a half cup of water with two spoons of common salt already dissolved in it, we can either heat the water in a pan on a stove or we can keep the water out in sun in a plate. Heat will evaporate the water in form of water vapour leaving behind the salt.

Rooftop rain water harvesting is a method where ran water that falls on the rooftop of a building or house, is collected into storage tanks through pipes. To be fit for use this water needs filtering as it may contain soil. The same water can also be made to recharge ground water levels by directly sending the pipes into pits in the ground.