Large scale water purification comprises all steps except?

UPPSC-2021

Community Health Nursing

Medium

Appeared in: UPPSC-2021

Explanation

Water storage is the process of holding treated water in tanks, reservoirs, or water towers before it is distributed to consumers.
This is the final stage in the water supply system, occurring after the active purification process is complete.
While some natural purification can occur during storage, its primary purpose is to ensure a consistent supply of safe water, not to actively treat or purify it.
Therefore, among the choices provided, it is the one that is not a core purification step.

Option B: Disinfection is a critical and mandatory step in water purification. It involves adding chemicals like chlorine or using methods like UV radiation to kill pathogenic microorganisms (bacteria, viruses) that can cause disease.
Option C: Screening is the very first step in large-scale water treatment. Raw water from a river or lake is passed through large screens to remove debris such as leaves, branches, and trash before it enters the treatment plant.
Option D: Filtration is an essential stage where water is passed through layers of sand, gravel, and charcoal. This process removes fine suspended particles, protozoa, and bacteria, making the water significantly clearer and safer.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Steps of large-scale water purification as background academic context rather than a clinical decision trigger.
Understanding the principles of water purification is fundamental for community health nurses in preventing waterborne diseases such as cholera, typhoid, giardiasis, and hepatitis A.
Nurses play a key role in educating communities about the importance of safe drinking water and methods for household water treatment (e.g., boiling, filtering) during emergencies or when the municipal supply is unreliable.
In outbreak investigations, knowledge of the water treatment process helps in identifying potential points of contamination in the supply chain.

How to Approach the Question

First, identify the negative framing of the question, indicated by the word "except". This means you are looking for the option that does not fit with the others.
The question is about the steps of "large scale water purification". Recall or list the main stages involved in treating water for a city or town.
The typical sequence is: Screening -> Coagulation/Flocculation -> Sedimentation -> Filtration -> Disinfection.
Evaluate each option against this process.
Screening, Filtration, and Disinfection are all core, active steps in the purification process.
Water storage is the step that occurs after the water has been purified, to hold it before distribution. Therefore, it is the exception in the context of purification steps.

Concept Tested & Keywords

Concept Tested: Steps of large-scale water purification
Stem keywords: Large scale, water purification, steps
Lead-in keywords: except
Negative lead-in flag: The question asks to identify the option that is NOT a primary step in the water purification process.

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E6 Parks TextBook of Preventive & Social Medicine part 2 — Subpart B (pp 233-449 of 464) p. 28-30