Water is the most important substance needed for survival of living beings. Living beings cannot live long without water. Water is available in plenty on the earth.
More than three-fourth of the earth’s surface is covered with water in the form of seas, rivers and lakes. It is also found inside the earth’s crust. Most of the water that we get from the wells comes from this source.
The natural sources of water are rain, springs, wells, rivers and seas.
1. Rain water
Rain water is considered to be the purest form of natural water (distilled water) free from impurities. Water from sea and rivers get evaporated into water vapour by the heat of sun. During this process of evaporation, impurities are left behind. When the water vapours go high up in the air they condense to form clouds. The water drops come down as rain.
2. Spring water
Springs are formed by percolation of rain water into soil. Springs supply water to wells and lakes.
3. Well water
The rain water seeps through the soil and goes down and is stored over rocks or hard earth crust. On digging the well this underground water becomes available to us. This is known as well water. This water may not be pure and may contain impurities such as suspended particles, bacteria and other microorganisms.
4. River water
Rivers are formed by melting of snow on the mountain, and also sometimes from the rain water. River water is also not pure and is not fit for drinking.
5. Sea water
Out of all the sources, sea water is the largest natural source of water. However, it is also the source of common salt and other important chemicals. It is the most impure form of water. All the impurities dissolved in river water are carried into the sea. As such, sea water cannot be used for drinking purpose because of high salinity and impurities.