Introduction

Addition or presence of undesirable particles which lowers the quality of water is known as water pollution. In 1974 Government of India passed the Water pollution Act to safeguard our water resources. Water pollution is caused when water bodies such as rivers, lakes, oceans etc. are being contaminated by industrial and agricultural wastes. Polluted water adversely affects all life forms that are either directly or indirectly dependent on water.

Types of Water Pollutants

The pollutants causing water pollution are known as water pollutants these are of 3 types 

• Biological Pollutants: these include various pathogens, e.g; bacteria, virus, protozoan etc.

• Chemical Pollutants: it includes both organic and inorganic wastes, organic biocides such as DDT, PCBs. Inorganic chemicals such as- metals, phosphates, nitrates etc.
• Physical Pollutants: these include hot water, oil spills.

Sources of Water Pollution

There are a number of ways by which water pollution is caused, but the city sewage and industrial waste discharge are among the major sources of water pollution. There are also few indirect sources causing water pollution, these include the contaminants that enter the water supply via soil or groundwater systems and also through rain.

Soil and groundwater systems contain the remains of human agricultural practices and also industrial wastes that are being improperly disposed of. Based on the emission, water pollution is further classified into 2 types:

• Point Sources: it refers to the flow of pollutants into water via regular channels (due e. municipal and industrial discharge pipes).
• Diffusion Sources: the mixing of pollutants scattered on the ground into water is termed as diffusion source or nonpoint source e.g; agricultural runoff, fertilisers and pesticides.

Effects of Water Pollution

Water pollution effects depends upon the variety of pollutants and their concentration, but the major factor that determines the level of pollution is the location of the water resource.

Water bodies located near urban areas are extremely polluted, it is due to the garbage, toxic chemicals released by various industries and commercial establishments.

• Biological oxygen demand (BOD):discharging of domestic sewage into water resources increases the pollution of water which on the other hand increases the BOD of water to 4000 mg/L. BOD indicates the quality of wastewater.

• Effect on aquatic life: if the sewage quantity increases, then the entire dissolved oxygen gets consumed by the decomposer organisms. Thus, leaving nothing for respiration of fishes and other aquatic organisms. Therefore they get killed.

• Even the presence of large amounts of nutrients in water is harmful for aquatic life as it results in excessive growth of planktonic algae, known as algal bloom. They lead to deterioration of the water quality and fish mortality. This algal bloom causes scarcity of oxygen(known as Eutrophication)

• Effects on human life: sewage from homes as well as hospitals consists of many undesirable pathogenic microorganisms. Disposal of these wastes without proper treatment into water causes the outbreak of various diseases, such as- dysentery,  cholera, typhoid etc. Thereby affecting human life.
• Effects  on food chain: sometimes few toxic substances present in industrial waste waters undergo biological magnification (also known as biomagnification) in aquatic food chains. Biomagnification deals with an increase in concentration of toxicant at successive trophic levels. This is caused when a toxic substance gets accumulated by an organism and cannot be metabolised or excreted.

Minamata Disease

This is an example of organic toxicity. In Minamata Bay, Japan a factory was responsible for discharging mercury into water, this mercury was methylated via bacteria present in wastewater. These bacteria were ingested by fishes. Furthermore, the locals of that area were dependent on fishes as a source of their food. These people began to develop signs of neurological damage, including visual loss hearing loss. Babies that are exposed to methylmercury inside the uterus were more severely affected.

Prevention and control of Water Pollution

There are different methods too . rather than releasing sewage waste into water bodies, it is preferred to treat them before discharge. Thus, practicing this treatment method can reduce the initial toxicity whereas the remaining substances are themselves degraded and rendered harmless by the water body. Secondary treatment makes the water reusable in the sanitary system and agricultural fields.

Water hyacinth, a plant has the ability to absorb dissolved toxic chemicals such as cadmium. Growing up of these plants to regions prone to such pollutants lowers the extent of adverse effects to a greater extent.

The very famous 3 R’s  i.e. reducing, reusing and recycling processes helps in overcoming the effects of water pollution in the long run. Besides this, there are also some chemical methods that control water pollution including reverse osmosis, precipitation, ion-exchange methods and coagulation.

Conclusion

As we all know that there is no life without water. So, we all need to conserve and keep the water clean. In this article we have discussed the various ways by which we can keep the water clean and safe for drinking. We must all remember that small steps from every individual can make a huge difference in controlling water pollution.