How Much Does It Cost to Install a Backwater Valve?

While most homeowners are aware that heavy rainfall can cause flooding, there's a much nastier (and stinkier) potential pitfall of torrential rain: sewage backing up inside your home. Sewage backflow can let potentially dangerous germs into your living area and cause extensive damage, so preventing this problem should be at the top of your to-do list if you live in an at-risk area.

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Installing a backwater valve is a relatively straightforward way to keep sewage flowing in the right direction.

What Is a Backwater Valve?

Fitting a backwater valve ensures waste only flows away from your home into a sewer system. During heavy rainfall, excess water can dramatically increase the volume of wastewater inside a municipal sewer system. This increased volume may cause sewage to flow the wrong way, potentially reentering your home and causing sewer line backups. Your home is at an increased risk of this unpleasant problem if it has a basement or sits close to street level. Installing a backwater valve is an excellent way to prevent the damage and health risks caused by sewage backups.

Most backwater valves contain a flap with floats attached and sit inside your main sewer line. During normal operation, the valve remains open to allow sewage to flow away from your house. When sewage starts to flow the wrong way, the flap floats rise as the volume of waste inside the pipe increases. The rising floats close the flap, blocking the path of the sewage before it enters your home.

Often, house builders install backwater valves when constructing new build homes, especially in areas with a higher risk of sewage backups. If you live in an older home that doesn't have a backwater valve, you can choose to have one retrofitted. The process involves excavating to access your sewer line, removing a piece of the pipe and installing the new valve in the gap.

Are There Different Types of Sewage Backwater Valves?

There are two main types of backwater valves: mechanical and manual. Mechanical backwater valves are popular because they automatically close in the event of sewage backflow, eliminating the need for manual intervention. They can protect your home against sewage backups, even if you're not there. However, they can be more challenging to install in preexisting plumbing systems and require regular maintenance.

Manual valves are easier to install in older homes and require the homeowner to manually shut the gate to prevent sewage backflow, usually by turning a small wheel or knob. In other words, you must close the valve yourself when you notice sewage backing up inside your house and wait until your sewage service provider says it's safe to reopen the valve. Therefore, you'll need to be at home to protect your house against sewage damage, which could be a disadvantage if you regularly travel out of town.

Both types of valves come in horizontal and vertical versions to suit your existing plumbing system. A qualified plumber can advise you on the most suitable options for your setup.

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How Much Does Sewer Backwater Valve Installation Cost?

According to HomeGuide, backwater valve installation costs between $200 and $1,000 (CAD 275 and CAD 1,373) on average. This price range includes the cost of the backwater valve and installation labor.

You could pay less to install a backwater valve to protect a single appliance or fixture. Single-appliance valves usually cost $40 to $100 (CAD 55 to CAD 137) for the device itself. Expect to pay a professional plumber between $75 and $150 (CAD 103 and CAD 206) to install the valve.

Following installation, you should consider having your backwater valve professionally tested each year to ensure it functions correctly. A faulty backwater valve can cause significant problems, such as preventing waste from flowing out of your home. Your jurisdiction may require you to commit to regular testing if you have a septic tank. Most homeowners pay between $30 and $300 (CAD 41 and CAD 412) for backwater valve testing.

All CAD conversions are based on the exchange rate on the date of publication.