Water is the most essential substance required by all humans, plants and animals. We cannot imagine life without water but nowadays water on earth is getting polluted which has become a topic of discussion. Polluted water can badly affect our health and also the animals living underwater because the life on earth is completely dependent on the water.
Water pollution is the chemical, physical or biological change in the quality of water or when it is accompanied with anthropogenic contaminants it becomes unusable. It generally happens when toxic substances are released into the water bodies by the public or the industries. These substances lie on the bottom of the ocean and rivers and sometimes remain suspended which destroys the quality of water. They not only pollute the ocean water but also reach the fresh groundwater used for the drinking and other household tasks.
Different types of water pollution:-
Generally water gets polluted by the human activities but sometime it happens through natural process like volcanoes, blooms, algae, earthquakes and from atmosphere through rainwater.
Bacteria, virus, protozoa also causes the water pollution which adversely affects on the aquatic life and the people who drink this water or even swim in that water. It can cause the diseases like polio, cholera and waterborne.
Industries release many metals and solvents and even poisonous chemical wastes into the water bodies which are very harmful for the water animals. Sometimes these chemicals have unpleasant smell. The Niagara River which is in between United States and Canada at one time caught fire because it was polluted by wastes of flammable chemicals.
These are the substances which when broken down are consumed by the microorganisms for their food. We think that these substances do not cause harm because they will not remain in the water for long time but they can reduce the amount of oxygen in the water. This dissolved oxygen is consumed by fishes and other aquatic animals. So if too much of bio-degradable substances are released in the water it can harm the fish to a great extent.
When the phosphorous and nitrogen mixes with the water they cause the quick growth of underwater plants and weeds moreover they grow bigger than their original size. This is another type of pollution. This makes it unpleasant in taste and unsuitable for swimming and boating.
The way to prevent water pollution from the waste water of industries and houses is to collect that water in sewer through underground pipes. There the water is treated so that it cannot harm the water body in which it is going to be released. The places where the above facility is not available there on-site systems or septic system is used.