National baseline
The National Plumbing Code specifies where floor drains are required, trap seal protection requirements, and backwater valve provisions.
Canadian building code question
What are the building code requirements for floor drains in Canada?
Floor drains are required in specific locations including mechanical rooms, laundry rooms, public washrooms, parking garages, and commercial kitchens. Requirements cover trap seal protection, backwater valve installation, drain sizing, and connection to the sanitary or storm drainage system.
Floor drains are required by code in locations where water spills, equipment drainage, or cleaning activities are expected. Beyond simply providing a drain, the code mandates trap seal protection to prevent sewer gas entry, backwater valves to prevent flooding, and proper connection to the correct drainage system. Missing a required floor drain or trap primer is a common code deficiency.
What to check first
- Floor drains are mandated in specific room types where water accumulation is expected — not in every room.
- Trap seal protection (trap primers or trap seal devices) is required for floor drains that may lose their water seal from evaporation.
- Backwater valves are required on floor drains below the flood level of the building sewer to prevent backflow.
Jurisdiction notes
Province and edition check
Provincial plumbing codes may add floor drain requirements for specific room types or amend trap primer and backwater valve provisions.
Municipal sewer bylaws
Municipal bylaws may add backwater valve requirements or restrict discharge of floor drain water to the storm system.
Work through it in this order
- Identify all rooms where floor drains are required by the applicable plumbing code.
- Determine trap seal protection requirements for each floor drain based on expected use frequency.
- Check backwater valve requirements based on the drain elevation relative to the building sewer flood level.
- Verify whether each floor drain connects to the sanitary or storm drainage system.
Common questions
Where are floor drains required?
The plumbing code mandates floor drains in mechanical rooms, laundry rooms, commercial kitchens, public washrooms, parking garages, and other locations where water accumulation is expected. The specific list depends on the code edition.
What is a trap primer and when is it required?
A trap primer is a device that periodically adds water to a floor drain trap to maintain the seal. It is required for floor drains that are not regularly replenished by normal use and would otherwise dry out.
When is a backwater valve required on a floor drain?
A backwater valve is required on floor drains installed below the flood level rim of the building sewer to prevent sewer backflow during surcharging events.