Which of the following is the longest source of water pollution in major rivers of India?

Water pollution in major rivers is a significant environmental issue, especially in countries like India, where many rivers serve as vital sources of drinking water, agriculture, and industry.

 Key Points

• Various factors contribute to the degradation of water quality in rivers, including untreated sewage, agricultural runoff, industrial waste, and religious practices. 
• The longest source of water pollution in major rivers of India is untreated sewage.
• A large portion of the population in India still lacks access to proper sanitation facilities, resulting in untreated sewage being discharged directly into rivers.
• This contributes to the spread of waterborne diseases, depletion of oxygen in the water, and an overall decline in water quality.
• The sheer volume of untreated sewage flowing into rivers makes it one of the most significant and persistent sources of water pollution in India.

Hint

•  Agriculture runoff contributes to water pollution through the excess use of fertilizers and pesticides, leading to nutrient loading and harmful algal blooms. While it is a major concern, it is often not as pervasive or immediate as untreated sewage.
• Unregulated small-scale industries can also pollute rivers, but their impact tends to be more localized and dependent on the industry type. However, in some regions, this could still contribute significantly.
• Religious practices such as immersing idols and offering prayers with materials that degrade in water do contribute to pollution, but they are not as significant a long-term source as untreated sewage.

Hence, the correct answer is Untreated sewage.