Class 8 Science
Water is necessary for living beings. All of us need water in order to survive.
Many of you must be drinking water that comes from water purifier. Water purifiers have become a necessity because of high level of pollutants in water.
In this lesson, you will read about causes and effects of water pollution and about prevention of water pollution.
Table of Contents
Addition of unwanted substances in water which makes water harmful for living beings and non-living things is called water pollution.
Water Pollutants: Substances which contaminate water are called water pollutants.
Pollution of Ganga
Ganga is an important river for a large section of people of India because millions of people depend on this river for their livelihood. Moreover, Ganga is considered to be a sacred river by majority of people in India.
As per a recent study by World Wide Fund for Nature (WWF), Ganga is one of the most polluted rivers.
Some of the causes of pollution of this river are as follows:
- Untreated sewage and effluents from cities are discharged into this river.
- River is used by people for bathing and washing clothes, also for bathing their cattle.
- Cremation of dead bodies on the banks of the Ganges is an age old practice, and this practice pollutes the river water.
- Rivers are preferred for immersing idols, flower and many other leftovers of rituals and worships.
- Many industrial towns are situated on the banks of this river, e.g. Kanpur.
- There are about 5000 industrial units in Kanpur; which include fertilizer, tanneries and paint industries. These factories release harmful chemicals into this river.
- Rampant use of weedicides, pesticides and chemical fertilizers pollute river water and groundwater.
Effects of Water Pollution:
Eutrophication: Enrichment of water body with nutrients is called eutrophication. It happens because of excess amount of chemicals in water. This results in proliferation of algae and other plants in water bodies with stagnant water. Once these plants die, they are consumed by decomposers. The process of decomposition utilizes most of the oxygen from water. This results in deficiency of oxygen for aquatic animals.
- Contaminated water becomes unfit for consumption by humans and cattle.
- It results in drastic reduction of fish population. Fall in fish population results in loss of livelihood for fishermen.
- Water pollution results in increased cases of water borne diseases; like cholera, diarrhoea, jaundice, etc.
- Presence of faecal matter results in high concentration of E.coli in water; which causes water borne diseases.
- Contamination of groundwater results in high levels of toxic materials in fruits, vegetables and grains.
- The pH and temperature of water increases because of untreated effluents from factories. This harms the aquatic plants and animals.
Water which is fit for drinking is called potable water. A quarter of the world’s population does not have access to safe drinking water.
Methods of Water Purification:
- Municipal bodies purify water by various physical and chemical methods before supplying drinking water to households.
- Filtration is a common method of purification of water. Various types of water filter are used in households.
- Boiling is another common method of water purification. It kills the germs in water.
- Chlorination also helps in killing the germs in water. Chlorine tablets are available for free at government hospitals.
How to Prevent Water Pollution:
- Discharge of untreated sewage and effluents in water bodies should be strictly prohibited.
- Every city should have a sewage treatment plant.
- Public awareness about harms of idol immersion should be increased.
- Traditional crematoriums should be replaced with electric crematoriums.
Conservation of Water
- Water is a precious resource, and hence every step should be taken to conserve water.
- We should follow the principles of three Rs, i.e. Reduce, Reuse and Recycle to conserve water.
- We should make changes in our lifestyle to prevent wastage of water.
- Leaking taps should be immediately repaired.
- Using a bucket instead of shower for a bath helps in saving water.
- Water left after washing clothes and vegetables should be reused for mopping and for washing cars and scooters.
- Sewage water should be purified so that it can be used again.
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