Restaurant Plumbing Design According to Code in Canada

This article explains how to design restaurant plumbing systems in Canada according to the National Plumbing Code (NPC), provincial building codes and municipal by‑laws. It covers water‑supply sizing, drainage and venting, grease management, sink requirements and backflow prevention so restaurateurs and engineers can plan compliant commercial kitchens.

 

Introduction

A restaurant’s plumbing network must deliver clean water and carry away waste while meeting strict health and building regulations. Canada uses the National Plumbing Code of Canada (NPC) as the baseline for all plumbing systems. Provinces like Ontario adopt the NPC and add provincial requirements via the Ontario Building Code (OBC), and municipalities enforce local by‑laws, such as the Toronto Sewer Use By‑law, that address issues like grease traps and waste disposal. Compliance is essential because failed inspections delay opening, lead to fines and can even result in business closures. This guide summarises the key elements of restaurant plumbing design so you can plan a system that is safe, code‑compliant and efficient.

 

 

 

 

Code landscape – national, provincial and municipal requirements

The NPC sets out technical requirements for plumbing design, including pipe sizing, fixture units, venting and materials. Provinces adopt these rules, and in Ontario they form Part 7 of the Ontario Building Code (OBC). Municipalities then layer on by‑laws that address local concerns. For example, cities such as Toronto, Vaughan and Mississauga impose stricter requirements for grease traps, backflow devices and wastewater quality. Health authorities also enforce public‑health standards, such as providing hand‑washing sinks, mechanical ventilation and sanitation equipment. When designing a restaurant, consult the NPC, relevant provincial building code and your municipality’s sewer‑use by‑law.

 

 

Water supply and backflow prevention

Restaurants require high‑capacity water heaters and boilers to supply hot water for cooking, cleaning and sanitation. Water pressure must remain consistent across multiple fixtures and peak usage times; designers often use booster pumps, pressure‑reducing valves and storage tanks to manage flow. Code compliance also demands cross‑connection control: potable water must be protected from contamination by installing backflow prevention devices (e.g., reduced‑pressure zone valves or double check valves) and testing them annually. Commercial plumbing systems typically include multiple risers, high‑capacity boilers, touchless fixtures and backflow preventers.

 

 

Fixture units and pipe sizing

The OBC and NPC assign fixture‑unit values to each plumbing fixture (e.g., sinks, toilets, dishwashers). Engineers sum these values to calculate the design flow and determine pipe diameter and slope. Oversized pipes waste money and hinder self‑scouring; undersized pipes lead to blockages and inspection failures. Always use the fixture unit tables in the applicable code when sizing water supply and drainage pipes.

 

 

Drainage and venting

A commercial kitchen generates large volumes of wastewater containing food scraps, fats and detergents. The drainage system must transport this waste to the sanitary sewer without causing backups or allowing sewer gases into the kitchen. Key design principles include:

• Slope and pipe sizing: Drain pipes must be sized for peak flow and sloped adequately to ensure efficient drainage. EB3 Construction’s guide notes that the piping network uses corrosion‑resistant materials (stainless steel or cast iron) and proper slope for efficient drainage. Large‑diameter main drain lines are often required in commercial plumbing to handle simultaneous flows from multiple fixtures.
• Venting: Each fixture and branch must be vented per code to prevent siphoning of trap seals. Venting also allows sewer gases to escape safely. EB3 emphasises venting to prevent siphoning of trap seals and calls for accessible foul‑air traps, while North Point highlights that all fixtures must be vented and slopes strictly enforced.
• Clean‑outs: The drainage system should incorporate clean‑outs at strategic points to facilitate maintenance and inspection. Designs should allow accessible clean‑outs at the end of horizontal runs and at each change of direction.

 

 

Indirect waste and air gaps

Health codes require indirect waste systems for equipment such as ice machines and refrigerators to prevent backflow contamination. Wastewater from these appliances must discharge to a floor sink or hub drain through an air gap an unobstructed vertical space between the outlet of the waste pipe and the flood‑level rim of the receptor. EB3’s guide states that air gaps must be at least twice the diameter of the outlet pipe or no less than 1 inch, and that floor sinks or hub drains with sloped floors help ensure proper drainage.

 

 

Grease management: traps and interceptors

Fats, oils and grease (FOG) solidify in pipes, causing blockages and sanitary sewer overflows. Canadian municipalities therefore mandate grease interceptors for food service establishments. The City of Toronto explains that establishments that cook, heat, process or prepare food must install and maintain a grease trap on any pipe connecting to the sanitary sewer. Facilities that fail to install or maintain grease traps may face fines up to $100,000. The interceptors should be connected to all fixtures that discharge FOG such as dishwashers, sinks, floor drains and wok stations. EB3 notes that interceptors separate grease from wastewater and must be sized based on fixture flow rates and local code requirements. Grease management systems require regular maintenance; interceptors should be cleaned before FOG and solids exceed 25 % of capacity, typically monthly. There are hydromechanical traps, gravity interceptors and automatic grease recovery units; consult local by‑laws for acceptable devices.

 

 

Sink requirements and sanitation fixtures

Health authorities require specific sinks for food preparation, dishwashing and hand washing. The City of Hamilton’s food‑premises guide states:

• Hand‑washing sinks: A separate hand sink must be located in each food preparation area and equipped with single‑use paper towels and liquid soap in a dispenser. Toronto’s student nutrition program guidelines also list a dedicated hand‑washing sink with hot and cold running water, soap and paper towels as mandatory equipment.
• Dishwashing sinks: If reusable dishware is used, a three‑compartment sink or an approved commercial dishwasher is required for washing, rinsing and sanitising. Where only single‑use utensils are provided, a two‑compartment sink is required. Even when a commercial dishwasher is installed, a two‑compartment sink large enough to hold the largest pot should be provided.
• Mop/service sinks: A separate mop sink (also called a service sink) is recommended to dispose of mop water.

 

 

Ventilation and mechanical integration

Plumbing design is closely tied to mechanical systems. Hamilton’s guide requires mechanical ventilation vented to the outside for cooking equipment, dishwashing equipment and washrooms. Commercial kitchens need exhaust hoods equipped with fans, canopies and filters to remove grease‑laden vapours and comply with NFPA 96 and local fire codes. Designers should coordinate plumbing and HVAC systems to ensure ducts and vents do not interfere with piping, and that make‑up air systems provide adequate airflow.

Best practices and recommendations

1. Engage licensed professionals: Commercial plumbing requires expertise in hydraulic calculations, code interpretation and integration with electrical, HVAC and structural systems. Hire a licensed mechanical engineer and certified plumber early in the design phase.
2. Coordinate with inspectors: Submit plans to municipal building departments and health inspectors for review, and schedule field inspections during construction to ensure compliance.
3. Plan for maintenance: Incorporate accessible clean‑outs, trap primers, inspection ports and shut‑off valves. Schedule regular maintenance of grease interceptors, backflow devices and vent systems to avoid costly downtime.
4. Use durable materials: Select corrosion‑resistant piping (stainless steel, cast iron) and NSF‑certified fixtures. Ensure floor drains have removable strainers and rounded corners for easy cleaning.
5. Design for accessibility: Ensure plumbing fixtures comply with accessibility standards (e.g., AODA). Provide lever‑type or sensor‑activated faucets and ensure sinks are wheelchair accessible where required.

Conclusion

Restaurant plumbing design in Canada must align with multiple layers of regulation. By following the National Plumbing Code, provincial building codes and local by‑laws, restaurateurs can ensure safe water supply, effective wastewater management and hygiene compliance. Key considerations include proper pipe sizing and venting, installing and maintaining grease interceptors, providing dedicated hand‑washing and dishwashing sinks, and integrating plumbing with mechanical systems. Investing in professional design and regular maintenance protects public health, avoids costly fines and ensures your restaurant operates smoothly.

 

Research sources

• City of Toronto: Mandatory Grease Traps for Food Service Establishments – states that establishments that cook or prepare food must install and maintain grease traps on any pipe connected to the sanitary sewer and warns that failing to comply can result in fines toronto.ca.
• EB3 Construction: Commercial Kitchen Plumbing and Drain Requirements – describes essential drainage components, sizing of grease interceptors, proper piping slope, venting and the need for air gaps in indirect waste systems blog.eb3construction.com
• City of Hamilton: Food Premises & Food Handling Requirements – outlines sink requirements (hand‑washing, dishwashing and mop sinks), mechanical ventilation and other equipment for food premises hamilton.cahamilton.ca.
• North Point Plumbing: Residential, Commercial and Industrial Plumbing Explained – explains that commercial plumbing systems require grease interceptors, backflow prevention devices, venting and compliance with the OBC, NPC and municipal by‑laws northpointplumbing.ca
• EB3 Construction & North Point Plumbing articles also highlight the importance of pipe sizing, venting, cross‑connection control and maintenanceblog.eb3construction.com northpointplumbing.ca.