Water essentially sustains all forms of life on our planet. We can even hardly think of any object or activity related to our very existence that doesn’t directly or indirectly need water.
It is well known that scientists in their quest for existence of life on different planets in the universe do investigate about the presence of water; if water can be found in any of its forms – solid, liquid or vapor, it sure would indicate to there being a possibility of existence of life.
Earth is covered up to as much as 75% of its total surface with water; even a cursory look of the geographical globe brings to our notice that massively large areas comprise oceans; ground areas too are interspersed with rivers and water bodies.
Surprisingly, water as a compound comprises atoms of two gases; hydrogen and oxygen hence the term H2O. Together in a definite proportion, they take the form of a liquid under normal temperatures that we are so familiar with; and call it water.
At freezing atmospheric temperatures, water solidifies in the form of snow while at around 100 degrees Celsius it takes vapor form as steam.
The most abundant physical form in which water is present in nature is liquid filling huge oceans and lakes; just less than 2% is found below the earth surface and even smaller percentage as atmospheric vapor.
The natural water cycle ensures that water keeps changing from one state to another and on the whole maintains its presence in adequate quantities for life on earth, be it aquatic or terrestrial, to carry on and flourish. Cloud formation resulting in rains plays an important role in the perpetuation of water cycle.
Huge evaporation of water from the vast surfaces of oceans, lakes and rivers, creates concentration of water vapor in the atmosphere which under suitable natural conditions returns to earth in the form of condensed water i.e. rain.
In certain parts of Asia and Europe, water gets converted into snow or sleet while there are areas like deserts that have hardly any rain and continue to remain dry and arid.
We should not go by the abundance of water in various forms as far as drinking water needs are concerned. The reason is that very small percentage of water really is safe for drinking purposes!
Water in the oceans and seas has a heavy salt content that only supports marine forms of life. It’s not easy to process it to make it portable.
Human and animal life is dependent on resources of fresh water, like fresh water lakes and rivers. Sub-soil water too provides a useful source of drinking water; machines like pumps are needed to bring it up to earth surface.
Man is therefore needed to strive constantly to ensure that enough drinking water is available on ground all the time for human, animal and plant life; the seeming abundance of water covering most parts of the globe does not make this strife any less. That succinctly emphasizes how precious water is!