Answer:
Water is one of the most precious resources the earth provides to mankind. Its use in modern age is manifold. We drink water to satisfy our thirst. We use it for domestic needs, irrigation, industrial use, transportation, power production and waste disposal. Water is universal solvent.
Thanks to our nature; it is very rich in water. About three-fourth of the earth's surface is covered with water. But only a small portion of total water resources is actually available for human use. Majority, about 97.3% is present in oceans and is salty in nature.
The fresh water constitutes only 2.7%. Out of this, inland" surface waters i.e. lakes, rivers, and ponds account for hardly 0.02%. This relatively negligible portion of the earth's water is crucially important to all form of terrestrial and freshwater aquatic life. We get water mainly from three sources;
1 Rain water.
2 Surface water
3 Ground water