Backwater valves

Install a backwater valve to help prevent wastewater backups in your home.

On this page

• Who should take action
• What it is
• Benefits
• What's involved
• When to do it

Who should take action

• Homeowners
• Landlords and property managers
• All homes with:
  • basements
  • ground-level floors
  • a history of basement flooding, particularly sewer backup
  • older municipal sewer infrastructure, especially in municipalities with combined sanitary and storm sewer systems

What it is

Wastewater and stormwater can be forced up the drainage system and into your home through the nearest exit possible, such as floor drains, toilets, sinks, shower drains or other plumbing fixtures, especially on lower levels of the home (including basements).

Backups can happen when:

• heavy rainfall or rapid ice and snowmelt overwhelms the municipal storm sewer system
• pipes are clogged

Backwater valves, also called sewer backflow valves, help prevent backups. They're devices installed on the pipe or pipes that carry wastewater from your home to your municipal sewer or septic system. This one-way valve allows wastewater to flow out of your home, and securely closes when backups or backflow is detected.

There are different types of backwater valves:

• Backwater valves that are normally open allow wastewater to exit under normal conditions, and the gate or flap will close when backflow is detected
• Backwater valves that are normally closed, open only in one direction when wastewater is discharged

There are different models within the normally open and normally closed types. The type of backwater valve dictates where it's installed within the home's plumbing system. It's best to ask your plumber or installer which is the right valve or combination of valves for your home.

Benefits

Installing a backwater valve is a high impact action that can greatly reduce damage, financial loss and health risks by:

• protecting your basement, appliances and belongings from messy, disruptive and costly sewer backups which can cause basement flooding
• The average cost to repair a flooded basement is over $40,000 and could impact your insurance premium
• preventing wastewater containing raw sewage from entering your home to ensure a sanitary and healthy living environment for you and your family
• standing water and wet materials allow viruses, bacteria, and mould to grow

Flood cleanup: keep in mind indoor air quality

What's involved

Check with your local government about regulations such as permits or inspections required before installation.

Backwater valves should be installed by a licensed plumbing professional.

Professionals are required to follow guidelines in provincial and territorial plumbing and building codes. There may also be local guidelines that plumbers will have to follow.

Ask a professional installer to:

• Conduct a plumbing inspection to
• determine the cause of backups you may have experienced in the past
• confirm that a backwater valve is an effective flood protection measure for your home
• determine additional measures that may be required for the installation of a backwater valve, including disconnecting downspouts from sewers
• Obtain the required municipal permits before starting the work
• Homeowners and property owners are also responsible for being aware of municipal requirements, permits or information related to this work
• Assess the grading where the valve will be installed
• The ground must be sloped down and away from the backwater valve to direct wastewater toward the municipal sewer or septic system
• A professional may need to create the required drainage slope
• Break up a portion of your basement floor to expose and cut out a section of the existing sewer line, if necessary
• Install the backwater valve(s) according to the manufacturer's instructions and municipal rules, regulations and requirements
• Install an inspection chamber (access box) that sits flush with the basement floor to easily access the valve for inspection and maintenance
• Ensure all gaps around the installation are properly sealed to prevent leaks

When to do it

Backwater valves can be installed during the initial construction of a home or retrofitted into existing homes. Many municipalities require backwater valves to be installed in all new homes. It's possible that you already have a valve if your home was built within the last 20 to 30 years. The lifespan of a backwater valve depends on the model, usage and maintenance.

Backwater valve maintenance

It's highly recommended that you hire a plumber to inspect and maintain your valve. Depending on the type of valve, this may have to be done regularly, at least once a year in the spring.

If you are planning to maintain a valve yourself:

• Refer to your user manual for maintenance requirements
• Open the inspection chamber (access box) and inspect the valve
  • Many backwater valves have a transparent plastic top so that you can easily see inside before removing the cap
• Inspect seals and gaskets for signs of cracks or wear

Cleaning backwater valves

Clean your backwater valve at least twice a year to remove dirt and grease buildup:

1. Wear rubber gloves and safety glasses.
2. Open the inspection chamber followed by the cleanout cap to check for debris.
3. Flush the valve with hot, soapy water to remove stubborn grease.
4. Once cleaned, check to make sure the gate or flap moves freely.
5. Tightly secure the cap. Backwater valves can fail if the cleanout cap is not secure.
6. Repeat this process at least once a year.

Other tips

• Do not flush garbage or food waste, especially grease, down your drains
• Avoid activities that require a lot of water, such as taking a shower, bath, running the dishwasher or doing laundry, during heavy rain events
  • Activities that require a lot of water open backwater valves to allow wastewater to exit the home. If the system is overwhelmed due to heavy rain, the water can be forced back up and potentially cause basement flooding
• Ask for a valve that includes an alarm, or add an alarm to an existing valve. Valve alarms will notify you when the valve is closed. This will help you avoid causing a "self-flood" by using excess water when the valve is closed
• For backwater valves with transparent covers, check that the valve's flap or gate is closed during heavy rain

Be flood ready

Flood readiness requires regular upkeep just like any other home or property maintenance task. Make maintaining your backwater valve part of your annual maintenance checklist.

Seek support from a local professional, friend, family or neighbour if you're unable to complete this task on your own.