A municipal water treatment engineer checks the residual chlorine level at the consumer's tap. According to the Bureau of Indian Standards and WHO guidelines, the minimum acceptable free residual chlorine at the point of delivery should be:

• A 0.1 mg/L
• B 0.2 mg/L
• C 1.0 mg/L
• D 0.5 mg/L ✓

Explanation

WHO and BIS recommend a minimum free residual chlorine of 0.5 mg/L (0.5 ppm) at the point of delivery (consumer tap) to ensure microbiological safety throughout the distribution system. At the point of treatment/entry into distribution, a higher level of 0.2–0.5 mg/L is maintained, but 0.5 mg/L is the standard cited for the consumer end. The maximum permissible limit is 1.0 mg/L to avoid taste and odour complaints.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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