DrainCom Logo

What is backwater valve in basement?

Do you have a back water valve in your basement? More and more we hear this question from our neighbours, real estate agents, insurance representatives, and of course plumbers! And as professionals we should be able to provide a reasonable answer why one should go through the expense of such work and why they would need this in their basement.

The back water valve is a device that lets the water flow in one direction and if the water should attempt to flow back, completely shut down backward flow protecting your house. In simpler words it is a specially designed piece of pipe that lets the sewage flow in one direction however not letting it flow back by flapper that shuts the pipe. While we would never expect water to flow backwards and NEVER flow up, that is not always the case! The most common reason this can happen is blockage somewhere in the city drain…and when your neighbours continue to use their water systems (particularly the ‘out’ pipes to sanitation…the water has nowhere to go and pipes start to fill up; very bad! Gravity tells us that basements are the first victim. Another common occurrence is during and after heavy rain events, wherein public drainage and sewage systems can become overwhelmed and the same water fills up the pipes and again you’ve got backed up flooded basements.

backwater valve

Do you already have a backwater valve in basement installed?

Many of our customers are not sure if they even have back water valves installed on their house drains, especially new owners. In most cases back water valves are installed inside in basements, as it is much easier to maintain, clean or repair. As per the plumbing code it is the last device on any drain system just before the drain pipe leaves the home. This would indicate that the place you’d find it would be just before front the foundation wall in the basement. It should also have an access lid. Some very good renovations might have had it covered with hardwoods or tiles. Drain camera inspection might help with these…additionally back water valve could be installed outside as well.

Once the decision has been made to get one installed the first thing your plumber should do is employ a drain inspection camera to locate the pipe and mark the spot where back water valve should be installed. They would then apply for city permit, arrange an inspection and once cleared they can proceed with the work. Normally it takes one day, but sometimes due to soil conditions, accessibility of the spot where back water valve is to be installed it may takes two days.

You might have more nightmare scenarios with your sewage pipes!

First one thing needs to be made clear: a back flow protection valve WILL NOT fix your drains and cannot do their job and save your home from backups if drains have shifted, collapsed, there are tree roots intrusion, or grease deposit in the home drains. For example, a collapsed drain in the area between new installed valve and the city drain in the middle of the road. In this case sewage can fill up the drain pipe and eventually reach the valve, the flapper will close the line. However if the water continues to be used  it will continue to fill the

backwater valve3

drain pipe and show up in the lowest drain opening which normally is a basement floor drain, shower drain or even basement toilet. If the homeowner notices in time that is the one scenario, however if this continues the water is used on the ground or second floor, people taking showers, running dishwasher,  or washing machine!. We have seen the situations when the water was used for couple days, and by the time homeowners have noticed their customer floor and even furniture are destroyed. Very traumatic. All this can also happen if the same if the pipe has collapsed under the basement floor upstream of back water valve.

So the question might be, why then even install a backwater valve if it won’t protect my drains?

Short answer: Drain Camera Inspections. The reason we gave you those horrible examples is to show the importance of having your drains inspected by drain camera, and fixed before or at the time of installation.

Back water valve in basement is still a very important device. Why?

The City of Toronto just like most jurisdictions in the GTA are growing very fast, more and more houses have and are under construction, so that nearly all the vacant land is filled with large condominiums…all of this adds extra load to city drains. Many of these drain systems are older and not necessarily up to the job of all this recent building activity. Now after what we’ve described imagine that city drain has blockage, you’re looking at sewage backing up into basements…and it’s generally apartment and condo owners who will suffer! Another situation is there are still a lot of storm drains connected to sanitation. Again heavy rain events can overload a city’s drain system and water starts to back up into basements. In both situations a back water valve will protect your home and won’t let storm waters together with sewage water enter your basement. Now one might understand why installing such a device is a good move, especially with the weather changes over recent years, heavy downpours in short period of time becomes more and more common.

City of Toronto Backwater Valve Programs

The City of Toronto understands the importance of having back water valve installed in basements created a subsidy program called Basement flooding protection subsidy program that helps homeowners to pay for installation of this device.

This subsidy gives up to $3,400 in rebates, and just for back water valve installation up to 80% of the invoice for a maximum of $1,250. For example if the invoice for installation is $2500, 80% is $2000, your rebate will be $1,250.

Other rebates and subsidies available in this program is for sump pump installation and repair, and pipe severance and capping , which is basically disconnection of storm drains from sanitary pipe.


Call for your Backwater Valve Experts at DrainCom! 416-989-5757


Request a Free Estimate