What is the primary objective of disinfection in drinking-water treatment?

Introduction / Context:
Disinfection is the final barrier in drinking-water treatment, intended to inactivate pathogenic microorganisms that pose acute public-health risks. While some ancillary effects occur (e.g., slight taste or odour changes), the core goal is microbiological safety.

Given Data / Assumptions:

• Post-filtration disinfection with chlorine, chloramines, ozone, or UV.
• Target organisms include bacteria, viruses, and protozoa (where applicable).

Concept / Approach:
Filtration removes particulates and most turbidity, but residual microbes may remain. Disinfection ensures compliance with microbiological standards (zero detectable E. coli, very low coliforms) and provides a residual in distribution (for chlorine/chloramines). Hence, the correct objective is pathogen inactivation.

Step-by-Step Solution:

Verification / Alternative check:
Regulatory frameworks prioritize microbial criteria as the top safety requirement; disinfectants are dosed based on CT (concentration*time) for pathogen inactivation.

Why Other Options Are Wrong:

• Odour/colour/turbidity control are addressed mainly by upstream processes; disinfection is not designed for these aesthetic parameters.
• 'Improve taste only' ignores the health objective.

Common Pitfalls:

• Assuming chlorine removes turbidity; it does not.

Final Answer:
Destroy pathogenic and indicator bacteria