Which one of the following is the most important source of water pollution?

Sewage disposal

The correct answer is Option (1) → Sewage disposal

• Sewage disposal is a significant and common source of water pollution. Improper disposal of sewage, which includes domestic and industrial wastewater, can lead to the contamination of rivers, lakes, and other water bodies. Sewage often contains a variety of pollutants, including pathogens (bacteria, viruses), nutrients (nitrogen and phosphorus), organic matter, and chemicals. Untreated or inadequately treated sewage can introduce harmful pathogens into water sources, posing serious health risks. Waterborne diseases such as cholera, dysentery, and gastroenteritis are associated with the ingestion of water contaminated with human or animal waste.