Safety Codes Bulletin: Use of Schedule 40 PVC underground for sump pit discharge

Purpose

This notice is issued to address the practice of using Schedule 40 Polyvinylchloride (PVC) for sump pit discharge piping underground.

Discussion

According to the National Plumbing Code of Canada 2020 (NPC), Schedule 40 PVC pipe is not permitted for underground installations, due to its structural limitations and potential for damage when buried. For underground installations, the NPC recommends using more robust materials that can withstand soil pressure and other environmental factors. This ensures the integrity and longevity of the plumbing system, preventing leaks and other issues that could arise from using inappropriate materials.

Interpretation

The NPC requires that piping used underground for a drainage system must be able to handle soil pressure and other environmental factors present in a variety of soil conditions.

Table A-2.2.5 to 2.2.8 in the NPC identifies pipe and fitting applications and clearly identifies Schedule 40 and Schedule 80 PVC as being ‘not permitted’ for a drainage system underground. The table identifies alternate options that are permitted for underground use.

ABS (Acrylonitrile Butadiene Styrene) piping is one acceptable sump pit discharge piping material listed due to its durability and corrosion resistance. Its strength ensures that it can withstand the impact and pressures often associated with wastewater discharge applications from sump pits.

Requirements

Review Table A-2.2.5. to 2.2.8. - Summary of Pipe and Fitting Applications in the NPC to ensure materials utilized are approved for use. Further use of Schedule 40 PVC for sump discharge piping underground will not be acceptable.

Reference

National Plumbing Code of Canada 2020 (NPC)
Table A-2.2.5. to 2.2.8. - Summary of Pipe and Fitting Applications