Water Quality Parameters MCQ with answer and solution

Concept

Turbidity is a measure of the cloudiness of water caused by suspended and colloidal matter. As per Bureau of Indian Standards (BIS), the acceptable limit is 1 NTU and the permissible limit in the absence of an alternative source is 5 NTU.

Step-by-step solution

1. Identify the parameter requested: Permissible limit of turbidity in drinking water. 2. Recall the BIS standard IS 10500:2012 guidelines for drinking water quality. 3. Note that the acceptable limit is 1 NTU and the permissible limit in the absence of an alternate source is 5 NTU. 4. Match with the given options to select 5 NTU (Option C).

Explanation

According to IS 10500:2012 (Drinking Water Specification), the permissible limit for turbidity in the absence of an alternative source is 1 NTU, but it can be relaxed up to a maximum permissible limit of 5 NTU in the absence of an alternative source. In standard multiple-choice questions for competitive exams, 5 NTU is typically recognized as the maximum permissible limit for turbidity.

Why the other options are wrong

A: 10 NTU is excessive and exceeds the BIS permissible limit. B: 1 NTU is the acceptable limit, not the maximum permissible limit. D: 0 NTU is practically unachievable and not a requirement.

Shortcut

Remember '1 and 5': Acceptable limit = 1 NTU, Permissible limit in absence of alternate source = 5 NTU.

Common mistake

Confusing the acceptable limit (1 NTU) with the permissible limit in the absence of an alternate source (5 NTU).