One of the most essential resources on Earth is water. Water is the basic building block for all life on Earth, without it no living thing can survive. Water is the most plentiful natural resource on our planet,  That's why Earth is also called the "water planet". From space it looks predominantly blue, as 74 % of its surface is covered by water. Oceans contain 97 % of the earth's water while the remaining 3 % is classified as freshwater. Seventy-seven percent of this surface freshwater is stored as ice and 22% as groundwater and soil moisture. The remaining freshwater, making up less than 1 % of the world total, is contained in lakes, rivers and wetlands.

Water also helps in regulating the temperature of the Earth. It also helps in transporting essential nutrients through the land, air, and all living things. The flow of water through the atmosphere, biosphere, lithosphere, and hydrosphere is called the hydrologic, or water cycle.

Look what we do to the very scarce, extremely essential freshwater:

Every year we dump, 14 billions pounds of sewage, sludge, and garbage  into the world's water bodies  such as rivers, lakes and streams all of which eventually end up in  the oceans. 19 trillion gallons of waste also enter the water annually.

Essential commodity

Fresh water is becoming rare as its being plagued by more and more human generated pollution every day. It has been said that water will be "the oil of the 21st century," or "liquid gold," and that it will cause wars between nations.

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Main Causes of Water Pollution:

As the world has industrialized and its population has grown, the problem of water pollution has intensified. For many years, chemicals were dumped into bodies of water without concern. While many countries have now banned such behavior, it continues to go on even today. Water pollution is mainly caused by chemically treated and raw sewage, waste from domestic farm animals and industrial liquid waste. Other water pollutants include pesticides, nitrates, phosphates, metals such as copper, zinc, cadmium and mercury, and chemical wastes including complex organic compounds. In the sea, the majority of the pollution is from rivers and coastal discharge, some is from rainfall and some is as a result of illegal dumping from ships and boats.

There are many sources of water pollution, main two are as follows:
 

Direct and Indirect pollution -   Click Here to learn more

Direct sources include industrial liquid or solid waste released from industries, factories, refineries, waste treatment plants etc. Many developed countries including United States, Canada and UK etc these practices are illegal and heavily regulated but in many developing countries the problem still exists.

Indirect pollution is when pollutants enter the water source from contaminated soils, rain water or ground water. Agricultural practices contain residue such as fertilizers and pesticides etc. which when leached can pollute the both surface and ground water.

The effects of water pollution are many fold

Water supports life on Earth, If fresh water is polluted it leads to many short and long term fatal diseases among animals and plants including humans. Pollution of water can lead to:

a) Poisoning of drinking water sources such as surface water ( rivers, lakes etc. and ground water. 

b) Poisoning of water and food which animals eat and then pollutants can gets accumulated in animal's body. Such toxins are called bioaccumulated toxins. When we eat meat of these animals these toxins find its way to our bodies.

c) When Oceans, rivers and lakes gets polluted they lead to destruction of oceans river and lake water ecosystems.

d) Deforestation from acid rains etc.