For community water supply, what is the most appropriate single treatment for water drawn from a deep tube well (typically clear and low in turbidity)?

Introduction / Context:
Groundwater from deep tube wells is usually low in turbidity and free of pathogenic contamination due to natural filtration through geological strata. However, it may still contain microorganisms or viruses and must meet drinking water safety standards. Choosing the minimal, effective treatment avoids unnecessary costs while ensuring public health.

Given Data / Assumptions:

• Source: deep tube well (confined aquifer), generally clear with low suspended solids.
• No significant iron, manganese, or hardness issues indicated in the question.
• Objective: select the single essential treatment step for safe supply.

Concept / Approach:

Because turbidity is already low, coagulation, flocculation, and sedimentation are typically unnecessary. Filtration may not be required when particle load is negligible and well construction is proper. The indispensable step is disinfection (e.g., chlorination, UV), providing residual protection in the distribution system and inactivating potential pathogens that may enter during pumping or storage.

Step-by-Step Solution:

Verification / Alternative check:

Design manuals specify chlorination or UV as the required step for clear groundwater; additional treatments are added only if specific contaminants (iron, fluoride, arsenic) exceed limits.

Why Other Options Are Wrong:

• Pre-settling/coagulation/filtration: Target turbidity and colloids; often unnecessary for deep groundwater.
• Aeration: Used for iron/manganese/CO2 removal—only when such issues exist.

Common Pitfalls:

• Skipping residual disinfectant, leaving the system vulnerable to recontamination.
• Over-treating without a water quality basis, raising O&M costs.

Final Answer:

disinfection only