- June 19, 2025
- - In category: Blog
The Ontario Plumbing Code is the backbone of safe, efficient, and legally compliant plumbing systems across the province. With the 2025 updates now released, all licensed plumbers, apprentices, contractors, inspectors, and even designers must get familiar with the changes, many of which are driven by modern safety, environmental, and accessibility standards.
Whether you’re working on a new residential build, retrofitting an older property, or troubleshooting a commercial plumbing system, understanding the 2025 Plumbing Code is crucial. This comprehensive guide breaks down the major updates, explains what’s new, and gives you practical tips to stay compliant and inspection-ready.
What Is the Ontario Plumbing Code?
The Ontario Plumbing Code is the regulatory standard that governs plumbing systems across Ontario. It’s embedded within Part 7 of the Ontario Building Code (OBC) and ensures that plumbing systems are designed and installed to meet health, safety, water conservation, and durability requirements.
The code applies to all types of buildings:
- Residential Homes: From single-family dwellings to multi-unit buildings like duplexes and townhouses. All plumbing work—from kitchen remodels to full plumbing layouts—must meet code.
- High-Rise Condominiums and Apartments: Ensures adequate water pressure, drainage, and fire safety features like backflow prevention.
- Commercial Spaces: Includes retail units, restaurants, offices, and mixed-use buildings. Commercial plumbing must meet specific fixture count and flow requirements based on usage type and occupancy.
- Institutional Buildings: Such as schools, hospitals, long-term care homes, and child-care centres. These facilities have stricter guidelines for water temperature control, accessibility, and infection prevention.
- Industrial Facilities: Including manufacturing plants and warehouses. Requirements often involve chemical-resistant piping and specialized drainage systems for non-domestic waste.
- Public Infrastructure: Airports, community centres, government buildings, and more must follow plumbing standards for safety, durability, and accessibility.
The code is periodically updated by the Ministry of Municipal Affairs and Housing (MMAH) in collaboration with stakeholders and national code bodies. The 2025 edition reflects advances in plumbing materials, increased safety protocols, and environmentally conscious practices.
Why Is It Important to Follow the Code?
Adhering to the Ontario Plumbing Code offers several vital benefits, beyond simply following the law:
- Legal Compliance: Performing plumbing work without adhering to the code can lead to stop-work orders, failed inspections, municipal fines, or even lawsuits.
- Health and Safety: Code-compliant plumbing systems protect occupants from health hazards such as contaminated drinking water, sewer gas leaks, and scalding.
- Environmental Responsibility: Many code updates reflect the latest water conservation and energy-efficiency goals. For example, using low-flow fixtures and thermal insulation standards for hot water pipes.
- Cost Efficiency: While compliance may seem tedious, it prevents costly mistakes, pipe failures, rework, and system inefficiencies in the long run.
- Insurance and Warranty: Work that doesn’t meet code can void manufacturer warranties and insurance claims. Insurers often require documented proof of compliance for coverage eligibility.
- Reputation and Business Growth: Contractors who consistently pass inspections and deliver safe, code-compliant work gain trust, referrals, and better reviews.
Key Updates in the 2025 Ontario Plumbing Code
1. Safety & Accessibility Enhancements
The 2025 Ontario Plumbing Code puts a major emphasis on safety and accessibility, especially for vulnerable populations such as children, seniors, and individuals with limited mobility. These new regulations are aimed at preventing injuries, improving indoor air quality, and ensuring safer plumbing systems in both residential and institutional settings.
Hot Water Temperature Limits
Scalding injuries can happen in seconds, especially to young children, the elderly, or individuals with reduced sensitivity to temperature. To address this serious safety concern, the 2025 code introduces strict temperature regulations at the point of use.
- Maximum hot water temperature allowed at fixtures:
- 49°C (120°F) in most residential homes, hotels, schools, and commercial buildings
- 43°C (109°F) in healthcare facilities, daycares, long-term care homes, and other sensitive environments
- These temperature limits must be achieved and maintained using:
- Thermostatic Mixing Valves (TMVs): Devices that blend hot and cold water to a safe, controlled temperature before it reaches the fixture.
- Temperature-limiting devices: Built-in safety components in water heaters or faucet systems that cap the maximum output temperature.
“Installers must ensure that mixing valves are certified, properly calibrated, and accessible for maintenance.”
“Every shower, bathtub, and sink connected to domestic hot water must meet these limits—even during temperature fluctuations caused by simultaneous fixture use.”
This change is especially critical in multi-unit residential buildings and institutional settings, where user safety cannot be individually monitored.
Automatic Compensating Valves
Water temperature can fluctuate rapidly when multiple fixtures are in use or if water pressure suddenly changes (e.g., a toilet flush during a shower). To mitigate this, the new code mandates:
- Automatic pressure/temperature compensating valves must be installed on:
- All new bathtubs and showers
- Retrofits or replacements in existing homes where a fixture is being upgraded
- These valves work by:
- Adjusting the mix of hot and cold water based on real-time changes in water pressure
- Maintaining a stable, comfortable temperature, even if other fixtures are being used at the same time
This not only protects against scalding but also enhances user comfort and reduces temperature “shocks” caused by pressure fluctuations.
Plumbers must ensure these valves meet CSA standards and are installed according to manufacturer guidelines.
Radon Gas Protection
Radon gas is an odorless, radioactive gas that occurs naturally in soil and can seep into buildings through foundation cracks and plumbing penetrations. Prolonged exposure is a leading cause of lung cancer, especially in non-smokers.
To improve long-term air quality and health safety, the 2025 code requires:
- Mandatory radon mitigation rough-ins in all new residential buildings, including:
- Single-family homes
- Townhouses
- Condominiums
- Semi-detached and multi-unit dwellings
These rough-ins typically include:
- A soil gas collection pipe beneath the slab
- A vertical vent pipe is routed through the building
- A capped opening for future fan installation, if elevated radon levels are detected
While the system may not require activation during construction, it must be accessible and easily upgraded into a full mitigation system post-construction if indoor radon testing reveals unsafe levels.
This proactive approach aligns with health advisories issued by Health Canada and responds to rising awareness about radon in various Ontario regions.
Septic Tank Safety Enhancements
Septic systems—especially in rural or off-grid areas—pose unique safety hazards, particularly if lids are improperly secured or left exposed. The updated code introduces new child- and pet-safe design features.
- All new septic tanks must now include:
- A durable safety mesh or barrier beneath the access lid
- A tamper-resistant cover that requires tools to open, deterring unauthorized access
This is in response to documented incidents where:
- Children or animals fell into unprotected tanks
- Unsecured lids shifted due to ground movement or improper installation
These safety additions are non-negotiable for new installs and are strongly recommended for retrofits or lid replacements on existing systems.
In addition to safety mesh, licensed installers are encouraged to use warning labels and lockable riser systems to prevent accidents and meet inspection standards.
2. Drainage and Venting Requirements
Drainage and venting are essential components of any plumbing system. If not designed or installed properly, they can lead to slow drains, backups, sewer gas leaks, and costly maintenance issues. The 2025 Ontario Plumbing Code introduces several critical updates to enhance performance, accessibility, and safety.
Minimum Drain Slope Requirements
The slope of drainage piping determines how effectively wastewater flows toward the sewer or septic system. Poor slope can result in standing water, foul odors, and eventual pipe blockages.
Key Code Requirements:
- For drainage pipes 3 inches or less in diameter, the required minimum slope is 1 in 50 (or 2%). This means:
- The pipe must drop at least 1 unit vertically for every 50 units horizontally.
- Example: A 10-foot (120-inch) run must have a minimum drop of 2.4 inches.
- If achieving this slope is not feasible (e.g., in tight retrofits or shallow basements), the system must:
- Still ensure a minimum flow velocity of 0.6 metres per second.
- Be validated through flow calculations or inspection verification.
Installers should use laser levels or slope gauges to confirm compliance during rough-in. This ensures optimal waste flow and reduces the risk of inspection failures.
Cleanouts and Access Points
Cleanouts provide direct access to drainage pipes, allowing for easier maintenance, blockage removal, and camera inspections.
New Requirements:
- Cleanouts must be installed:
- At every change in direction greater than 45°
- At intervals no greater than 30 meters for horizontal drains
- At the base of every vertical stack
- Cleanouts must be:
- Easily accessible (not concealed behind walls, flooring, or permanent fixtures)
- Installed in locations that allow the use of tools or drain snakes without causing property damage
In commercial kitchens and high-use buildings, cleanouts may need to be installed at shorter intervals due to the higher risk of buildup.
Venting Systems and Air Admittance Valves (AAVs)
Proper venting is crucial to maintaining neutral air pressure in the drainage system, allowing wastewater to flow freely and preventing trap siphoning or gurgling sounds.
Traditional Venting Rules:
- Every fixture must be vented, either individually or via a branch vent.
- Vent pipes must rise vertically and terminate through the roof to the outdoors to release sewer gases.
Air Admittance Valves (AAVs) – What’s New:
- AAVs are now officially permitted under certain conditions, offering more flexibility for complex or space-constrained designs.
AAV Code Conditions:
- At least one vent pipe must terminate outdoors in every drainage system.
- The AAV must be:
- Installed no lower than 100 mm above the highest trap arm it serves
- Accessible for inspection and servicing
- CSA-certified and installed per manufacturer’s instructions
AAVs are especially useful in kitchen islands, basement renovations, or buildings with limited roof access, but they are not a full replacement for conventional vent stacks.
3. Approved Materials and Equipment
The 2025 code reflects ongoing advancements in plumbing materials and product certification. These updates not only allow for more cost-effective and energy-efficient installations but also aim to improve long-term system performance and durability.
Newly Approved Materials
One of the most notable updates is the inclusion of PE-RT (Polyethylene of Raised Temperature) tubing in potable water systems.
PE-RT Tubing:
- Now accepted for hot and cold water supply lines
- Must comply with CSA B137.18 standards
- Offers benefits such as:
- High flexibility for easier installation
- Thermal resistance suitable for hot water
- Better crack resistance and durability in freezing conditions
PE-RT is a popular choice for residential installations and radiant heating systems. It may gradually replace PEX in some markets due to its ease of use and performance.
Commonly Approved Plumbing Materials
Plumbers should continue using proven, code-approved materials based on the application:
- PEX (Cross-linked Polyethylene):
- Widely used for residential water systems
- Offers flexibility and chemical resistance
- Copper:
- Long-standing standard for water supply
- Excellent antimicrobial properties and durability
- CPVC (Chlorinated Polyvinyl Chloride):
- Suitable for hot and cold potable water
- Used in both residential and commercial settings
- PVC/ABS:
- Still standard for DWV (Drainage, Waste, and Vent) systems
- Requires proper support and certified solvent weld connections
Pipe Sizing and Joint Fittings
Pipe sizing charts in the 2025 code have been updated to:
- Reflect fixture unit load changes
- Account for new low-flow appliances
- Improve long-term flow efficiency and prevent clogging
Pipe Fittings & Connections Must Be:
- CSA-certified or meet other nationally recognized standards
- Installed per the manufacturer’s specifications
- Compatible with adjacent materials (e.g., transition fittings between copper and PEX)
Using the wrong fitting or unapproved material is a common cause of inspection failures. Always double-check part numbers, CSA labels, and connection instructions.
4. Water Heater and Plumbing Fixture Rules
Water heating systems are a key focus of the 2025 Ontario Plumbing Code updates, with new regulations aimed at increasing user safety, energy efficiency, and maintenance accessibility. These changes affect both new installations and retrofits in residential, commercial, and institutional settings.
Water Temperature Control and Scald Prevention
Water heaters must now limit the maximum outlet temperature at fixtures to prevent scalding injuries. This is especially critical in homes with young children, seniors, or persons with disabilities.
Code Requirements:
- Hot water delivered to fixtures must not exceed 49°C (120°F) in most buildings.
- In healthcare, childcare, and senior care settings, the maximum is reduced to 43°C (109°F).
- Must be achieved using thermostatic mixing valves (TMVs) or approved temperature-limiting devices, installed as close to the fixture as practical.
These valves must:
- Be CSA-certified
- Be accessible for future testing and maintenance
- Ensure consistent water temperature despite pressure or flow changes
Tip: Always install TMVs on the hot water outlet of water heaters and verify their function using calibrated thermometers during system testing.
Fixture Requirements in New Installations
Fixtures like bathtubs, showers, and sinks must now include safety-focused components:
- Showers and bathtubs must be fitted with automatic pressure/temperature compensating valves to prevent sudden hot or cold water shocks.
- Lavatories in care facilities require anti-scald protection built into the faucet or controlled by a TMV.
- Bathtub fillers must be equipped with backflow protection where required.
Shut-Off Valves in Multi-Unit and Residential Buildings
A major update to improve both safety and maintenance accessibility:
- Each dwelling unit in multi-unit residential buildings must have its dedicated shut-off valve for both hot and cold water lines.
- These valves must be:
- Clearly labeled
- Located in an accessible location (e.g., inside a utility cabinet or mechanical room)
This rule ensures that the water supply can be isolated in one unit without affecting neighboring units during maintenance or emergencies.
Practical Tips for Plumbers to Stay Compliant
- Attend Code Workshops: Keep your skills sharp by joining Ontario Plumbing Code training sessions, many of which are offered by trade schools or local building departments
- Use Certified Products: Only use fittings, pipes, and valves approved by CSA or recognized national standards.
- Double-Check Drain Slopes: Use digital or bubble levels when laying pipes—incorrect slope is a top reason for failed inspections.
- Label All Valves Clearly: Especially in multi-unit buildings, clearly marked shut-off valves make your work professional and future-friendly.
- Document Everything: Take photos, record installation specs, and maintain a checklist aligned with the code—this helps in inspections and legal protection.
FAQs About the 2025 Ontario Plumbing Code
When do the new changes take effect?
January 1, 2025. Projects with permits issued before this date may fall under the old code during the three-month grace period.
What is the required drain slope in Ontario?
For drainage pipes up to 3” in diameter, the slope must be 1 in 50. If this isn’t achievable, the system must still allow a minimum of 0.6 m/s gravity flow.
What’s the max hot water temperature at fixtures?
49°C in most residential and public settings. 43°C for vulnerable populations. Mixing valves are required to ensure consistency and safety.
Are Air Admittance Valves allowed?
Yes, but only if at least one outdoor vent stack is present and the AAV is at least 100 mm above the fixture’s flood level.
What new piping materials are allowed?
PE-RT tubing joins copper and PEX as an approved potable water supply material, provided it meets CSA B137.18 standards.
