Biochemical Oxygen Demand (B.O.D.): What is the permissible value of B.O.D. in safe drinking water according to environmental engineering standards?

Introduction / Context:
B.O.D. measures the oxygen consumed by microorganisms while decomposing organic matter in water. In safe drinking water, B.O.D. should ideally be zero to ensure purity and safety.

Given Data / Assumptions:

• B.O.D. values indicate pollution levels.
• Standards prescribe safe limits for potable water.

Concept / Approach:
B.O.D. is critical for wastewater quality but should be absent in drinking water. Hence, safe drinking water must have nil B.O.D.

Step-by-Step Solution:

Verification / Alternative check:
BIS standards confirm B.O.D. must be nil in potable water, while wastewater may allow measurable values.

Why Other Options Are Wrong:

• 5, 10, 15, 20: These values are acceptable for wastewater, not drinking water.

Common Pitfalls:

• Confusing wastewater B.O.D. with drinking water standards.

Final Answer:
Nil