An apprentice plumber is preparing to install a new 75 mm sanitary drainage pipe in a high-rise building. The design drawings specify a slope of 1 in 75. What action should the apprentice take before commencing installation?

Question: An apprentice plumber is preparing to install a new 75 mm sanitary drainage pipe in a high-rise building. The design drawings specify a slope of 1 in 75. What action should the apprentice take before commencing installation?

Answer options:

• Proceed with the installation as the slope is within acceptable limits for long runs.
• Increase the slope to 1 in 50 as per standard practice for sanitary drainage. ✅ Consult with the journeyperson or engineer, as this slope may be insufficient for a 75 mm pipe.
• Install a cleanout at every change in direction to compensate for the shallower slope.

Correct answer: Consult with the journeyperson or engineer, as this slope may be insufficient for a 75 mm pipe.

Explanation: According to the National Plumbing Code of Canada, a 75 mm horizontal drainage pipe requires a minimum slope of 1 in 50. A slope of 1 in 75 is shallower than the minimum required, which could lead to inadequate flow velocity and solids settling. Therefore, the apprentice should consult a journeyperson or engineer to address this discrepancy before installation.