A plumber is sizing the cold water supply for a small commercial building with a peak demand of 2.0 L/s. The building is supplied by a municipal water main with a pressure of 450 kPa. The total equivalent length of piping from the main to the furthest fixture is 60 metres, and the elevation difference is negligible. Which pipe material and size combination would be most appropriate to maintain adequate pressure at the furthest fixture, assuming a typical design velocity?

Question: A plumber is sizing the cold water supply for a small commercial building with a peak demand of 2.0 L/s. The building is supplied by a municipal water main with a pressure of 450 kPa. The total equivalent length of piping from the main to the furthest fixture is 60 metres, and the elevation difference is negligible. Which pipe material and size combination would be most appropriate to maintain adequate pressure at the furthest fixture, assuming a typical design velocity?

Answer options:

• 25 mm Type L copper tube ✅ 32 mm Type M copper tube
• 38 mm Schedule 40 PVC pipe
• 50 mm PEX pipe

Correct answer: 32 mm Type M copper tube

Explanation: For a peak demand of 2.0 L/s, a 32 mm Type M copper tube would likely provide sufficient flow with acceptable pressure drop and water velocity. A 25 mm pipe would result in excessive friction loss and velocity. PVC and PEX pipes of similar nominal size often have smaller internal diameters, which would increase pressure drop for the same flow compared to copper.