Cast iron (CI) water mains: Evaluate the statements on common usage, corrosion resistance, service life, and usual manufactured lengths for municipal distribution.

Introduction / Context:
Cast iron piping has a long legacy in urban water distribution. Recognising its characteristics aids in maintenance strategies and in differentiating from ductile iron or steel in asset inventories and exam scenarios.

Given Data / Assumptions:

• Traditional CI standards and typical field experience.
• Use of cement mortar lining or bituminous coatings for corrosion control.
• Historic stick lengths used in many networks.

Concept / Approach:

CI was the standard for decades, replaced largely by ductile iron and other materials more recently. With proper external protection and internal lining, CI mains can resist corrosion reasonably and may last many decades to near a century, depending on soil aggressiveness and stray currents. Many legacy mains were supplied in shorter stick lengths compared to modern materials.

Step-by-Step Solution:

Verification / Alternative check:

Municipal asset records commonly show CI mains in service well beyond 50 years; renewal programs prioritise based on break history and risk, not solely age.

Why Other Options Are Wrong:

• Each individual statement is consistent with common practice; none alone contradicts standard knowledge.

Common Pitfalls:

• Confusing cast iron with ductile iron, which has superior toughness.

Final Answer:

All of the above.