Pressure capacity of PVC (UPVC) water mains Approximate maximum hydrostatic pressure head that standard PVC pressure pipes can withstand under normal water-supply service conditions is closest to:

Introduction / Context:
PVC (UPVC) pressure pipes are widely used in distribution networks due to corrosion resistance, hydraulically smooth bore, and convenient jointing. Designers often convert pressure ratings expressed in bar to an equivalent water head for quick checks in field problems.

Given Data / Assumptions:

• 1 bar is approximately equal to 10 m of water head.
• Common PVC pressure classes include ratings up to about 10 bar in many standard municipal uses (with higher classes also available, but 10 bar is a typical design figure in textbook problems).
• Working conditions are steady with appropriate safety factors and temperature allowances.

Concept / Approach:
To translate pressure class to head: head (m) ≈ 10 * pressure (bar). Thus a 10-bar pipe corresponds to about 100 m water head. While higher-class pipes exist, the conventional “rule-of-thumb” ceiling often cited for standard mains in didactic questions is around 10 bar (≈ 100 m of head).

Step-by-Step Solution:

Verification / Alternative check:
Manufacturer catalogues and codes list multiple classes; for general exam purposes, 10 bar (≈ 100 m) is a standard benchmark.

Why Other Options Are Wrong:
25–75 m are below typical higher service classes; 125 m exceeds the common 10-bar textbook figure unless specially specified.

Common Pitfalls:
Ignoring derating for temperature and surge; selecting pipe class without checking transient pressures (water hammer) and test pressures.

Final Answer:
100 m of water head