How Can I Protect My Home from Flooding?

Cam Allen L.I.W. NHI

April 22, 2026

In this weekly Q&A column, retired builder/building inspector Cam Allen answers readers’ home renovation questions. Have a question? Enter it in the form below.

The intensity of rain storms has certainly risen in recent years, which has put pressure on groundwater management and municipal waste water systems that were not designed to manage these extremes.

In some towns and cities the sewage water and the stormwater are handled by one set of urban drain pipes and this has proven to quickly tax the system when excess groundwater arrives. These dual-use drainage lines also tend to get clogged from the debris they pick up from the roads. The average homeowner now has to realign their homes to withstand these climate factors.

Groundwater Flooding Protection

There has been an increase in companies that offer groundwater flooding protection systems in Canada. Companies like Flood Control Canada, Aquaverter, Vasalta, Floodshield and Barrier Solutions have all risen up to offer major flood control methods. Most of these methods are commercial flood control systems that are adapted for residential use.

Sandless Sandbags

Other companies offer products more residentially applicable like sandless sandbags. Quick Dam and Vevor Flood Barriers are two of the most widely known brands. All the major big box home stores carry these. Most homes will benefit from keeping a supply of sandless bags if they are in an area where the possibility of overland water invasion may occur.

Sandless sandbags, also known as water-activated flood bags, were invented a few years ago and are an innovative idea to replace the conventional sandbag. These bags are lightweight, they expand when water comes in contact with them and are as effective as sandbags. The major advantage is once the flood waters have receded, these bags simply dry out and you fold them up for reuse. They are also available in “sausage-like” bags with various lengths to put in front of your garage or patio door. I have seen these in action and they work just as well as sand-filled bags. In fact, unlike conventional sandbags that eventually rot out, these are reusable time and time again.

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Backflow Valves

The main issue homeowners deal with from extreme rain is sewage backup. This problem is controllable with a drain fitting called a backflow
valve (or backwater valve). These are now code in most municipalities and they should have been years ago. When a municipal blackwater or sewage system exceeds its capacity or a blockage happens, inevitably it ends up in your basement. This blackwater backs up, starting with your basement floor drain, then shows up in your basement tub or shower drain, then the toilet and finally any sink in the basement.

A backflow water valve is located just inside your home in your main sewer drain and should your sewer line start to back up, most of these have a spring-loaded flap that releases and seals off your sewage line from the municipal drain backflow. A backflow valve will cost you in the range of $300–700 depending upon quality and design plus the plumber’s installation charges. I recommend the kind with a clear plastic inspection cover so you can see if it’s working properly.

Read more on this topic in A Guide to Backwater Valve Installation.

Sewer Inspection Cameras and Augers

There is also a possibility that the sewer line from your home to the city drains is adding to the problem. If you find your home has an unpleasant odour and it is traced to a sink or your basement floor drain, this is a telltale sign. If you find your sinks are draining slowly, this is another sign.

Over time sewer lines can be affected by tree roots, settlement in the line and a joint failure that is allowing soil into the drain. Over time they will plug up and your home blackwater backs up into your home. This type of main drain issue is a lot more common than people think. In the past, the only solution was to dig up the lawn and replace the sewage line.

Today we have sewer inspection cameras that can scope inside your drain right out to the city drains and find any blockage that is increasing the chance of sewage backup issues. I have been present when a plumbing contractor inserted an auger into the sewer line, cleared the blockage and then restored the sewer line using a one-piece expandable liner fitted into the existing sewage line. This was done without the excavation disturbance needed to expose and replace the sewer pipe. While not a cheap repair, it was far less than the cost of excavation with a lot less household upheaval.

Backflow Preventers

For clarification, there are a couple of other drain fixtures that are sometimes confused with a backflow valve. One is called a “Backflow Preventer”. This fixture prevents the reversal of water flow and keeps non-potable water and contaminants out, keeping your potable water clean. They are commonly found on laundry sinks and are code in some regions.

Check Valves

The other valve that is widely used and comes by a number of names is the one-way valve, reflux valve or check valve, which is the most common name. You often see a check valve in the discharge line for a sump pump. How these valves work is when the upstream pressure exceeds the downstream pressure by a certain amount, like the pressure created by a sump pump, this causes the valve to open and move not only the water it’s holding back but the water being moved by the sump pump, as one example. I have installed check valves in 1.5 inch and 2inch sink drains to act like a kind of backflow valve in specialized drain locations.

Along with a working, maintained sump pump that is exterior discharged
to an on-grade location at least 6 feet from your home, a backflow valve
should be installed in every urban home connected to a municipal sewage system.

Images from Depositphotos