Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The leakage losses are less when water supply is intermittent.
Reason (R): Pressure is less in intermittent water supply.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

While intermittent supply reduces leakage, it increases the risk of contamination! When pipes are empty, a vacuum can form, sucking in sewage or groundwater through the very leaks that weren't leaking water out.

Answer 1

The Correct Option is A

Concept: Water distribution systems can be continuous (24/7) or intermittent (supply for fixed hours).

Step 1: Evaluate Assertion (A).
In an intermittent supply system, pipes are only pressurized and full for a few hours a day. During the remaining hours, there is no water in the pipes to leak out. Therefore, the total volume of water lost through leaks over 24 hours is significantly lower than in a continuous system where leaks occur constantly. Thus, (A) is correct.

Step 2: Evaluate Reason (R).
Intermittent systems are often operated at lower average pressures to conserve water or because the infrastructure cannot handle 24/7 high pressure. Since the rate of leakage through a hole is proportional to the square root of pressure ($Q \propto \sqrt{P}$), lower pressure results in less water being pushed out through cracks. Thus, (R) is correct.

Step 3: Connection.
The reduced pressure and duration directly explain why the total leakage is minimized in such systems.