The correct option is (b).
Explanation
Sanitation systems are designed to manage human waste safely to prevent environmental contamination. Improper disposal of excreta leads to the leaching of pathogens and chemical pollutants into the soil and underlying aquifers, posing significant public health risks.
Statement-wise Analysis:
- Statement 1 is Incorrect. Untreated human excreta is a major source of both soil and water pollution. When deposited on land, rainwater washes pollutants and pathogens into the soil. These contaminants leach downward through the soil profile and eventually reach the water table, thereby contaminating groundwater.
- Statement 2 is Correct. Groundwater contaminated by fecal matter often contains bacteria, viruses, and parasites. Consuming water from such sources is a primary transmission route for water-borne diseases, including typhoid (caused by Salmonella typhi), cholera, dysentery, and hepatitis A.
- Statement 3 is Incorrect. Septic tanks are low-cost, on-site sewage treatment systems specifically recommended for areas lacking sewerage networks. In areas with extensive centralized sewerage systems, household waste is transported via pipes directly to sewage treatment plants, rendering septic tanks unnecessary.
Key Takeaway:
Untreated human waste contaminates both soil and groundwater, serving as a vector for water-borne diseases. Septic tanks are decentralized sanitation solutions utilized primarily in the absence of centralized sewerage infrastructure.