Water- essential for Life.

Water is said to have come in existence million years ago, due to process of condensation of vapor. Water is nectar. Life could not exist without water on earth.
Our Scriptures make reference to water as sacred. River Ganga was brought unto earth by sage Bhagirath to meet with the demand of water on earth.
The Saraswati river is referred in the RigVeda more than 60 times. It is one of the seven sacred rivers Sapt Sindhu. Until recently, scholars considered the river to be mythical.

The Saraswati sprang from Himalayan glaciers in Har-ki-dun in Uttaranchal and emerged at Adi Badri, 30 km. north of Jagadhri, through the foothills of the Shiwalik ranges. The river at its peak was between 7-12 km wide at its widest point and traversed a distance of over 1600 km through Himachal Pradesh, Haryana, Punjab, Rajasthan to reach Sindhu Sagara, the Arabian Sea at Prabhas Patan Somnath,Gujarat.
Then, between 6000 BC and 4000 BC, tectonic changes caused river-migration and the desiccation of the river. It was completely dry by approximately 2000 BC.
The river had its origin at least as early as 12000 years BC.

Considering that the Rig-Veda mentions the river so frequently, it stands that the river must have been in its peak years. This implies that the Rig Veda must have been conceived in its present form between 12000 BC and 6000 BC.
They reference the water life cycle
Water ascends towards the sky in vapors;
from the sun it descends in rain,
from the rains are born the plants,
from the plants, are the animals and humans.

The huge volume of water contained in the oceans, seas rivers has been produced during the geologic history of the Earth. There is little information on the early history of the Earth's waters. The presence of water on the Earth at even earlier times is not documented by physical evidence. The early atmosphere is thought to have been highly rich in gases, notably in hydrogen, and to generate water vapor with reaction of oxygen.
The Earth's surface temperature and the partial pressures of the individual gases in the early atmosphere affected the atmosphere's equilibration with the terrestrial surface. Thus water in liquid form accumulated in isolated depressions of the Earth's surface, forming oceans.
Life originated in the oceans, and the chemical composition of body fluids in land animals reflects their primeval origin. The dependence of life on water is a must and it is the major constituent of plant and animal cells. Most of the major groups of animals still live in water, a relatively small number have adapted to life on dry land.
Water is required for a variety of purposes; water for drinking is still paramount, and such water must be relatively pure. If it is not supplied in sufficient amounts through precipitation, it must be supplemented by irrigation systems. Irrigation, however, is one of the most wasteful uses of water in areas in which it is scarce, because great quantities are lost through evaporation in both storage areas and transport. In many regions irrigation is, nevertheless, essential for human survival. Water is treated with chlorine to make it use-worthy for drinking purposes.
Water for transportation has always been important, as indicated by the fact that most major cities are located on the shores of oceans and other large bodies of water or along rivers and other types of navigable waterways. Despite recent advances in ground and air transportation, water transportation has an economic advantage for the movement of goods that have a relatively low value per unit of weight or volume, such as raw mineral ores, fuels, and various types of construction materials.
Water for urban use other than drinking serves a multitude of purposes, such as fire fighting, street cleaning, sanitation, and sewage disposal. Steel mills, pulp mills, chemical factories, and most other industrial processes that involve the conversion of raw materials into finished products require water.
Next to agriculture, one of the most extravagant uses of water is as a cooling fluid in the generation of power from fossil and nuclear fuels, with the latter consuming far greater volumes. Water has been used directly as a source of power since the time of the first boat and the first waterwheel. A small but important part of the world's electrical supply now is generated by hydropower, in which the force of falling water is used to turn turbines that produce electricity.