Basement flooding is a widespread problem and causes millions of dollars in damage to personal property, not to mention huge personal efforts in rehabilitation to fix the damage caused, and to replace items lost. Clearly, it is in a home owner’s best interest never to experience a basement flood at all. Whether you have flooded or not, part of this discussion will be based on principles of home plumbing and drainage reviewed in Causes of Basement Flooding. Additional resources are included at the end of this section.
Image: Is a summarized list of measures a home owner can take to protect their basement from flooding. If your home has a basement, you can have a basement flood. All measures listed will provide the knowledge and best practices on how to avoid a flood. However, the risk of basement flooding is never entirely avoidable. If you have a basement, there will always be a risk that conditions can occur that will cause a basement flood.
KNOWLEDGE AND UNDERSTANDING:
LIFESTYLE AND USE OF SPACE:
SIMPLE AND INEXPENSIVE:
HIGHLY EFFECTIVE, WITH MORE EFFORT AND EXPENSE:
Consider window wells and window-well covers
Part of reducing the risk of basement flooding for your home is having knowledge and a solid understanding of such things as the general flood risk of your area, what the municipality knows or does not know about it, insurance considerations, as well as basic knowledge about how your home’s plumbing and drainage systems work. The following section discusses five things you can do to improve your knowledge of flood risks and implications.
Stormwater, storm sewers and general surface drainage issues are managed by City Engineering.
Sanitary sewers and treatment are managed by your local municipality.
Whether your home has experienced basement flooding or not, one place to get started is your local municipality. Call your City’s Customer Service Representatives. They will help direct your queries in the right direction.
Some questions to ask municipal staff:
Basement flooding can occur at random locations, or it can occur in concentrated areas. Regardless, it is important to let the municipality know that your home has flooded, because it can help direct efforts to understand why flooding occurred there and may assist in identifying solutions for flood risk reduction in your area. The more reports that are filed from a given area, the more resources are likely to be committed to understanding the problem.
Part of reducing the risk of basement floods is to understand how your drainage and plumbing work. Every home is different, and homes over time have been built with ever changing building practice and building codes. Things that are valuable to know about your home’s plumbing include:
To understand these elements of your home’s plumbing, you may wish to engage a licensed plumber who can conduct specialized testing or inspection, perhaps through using a video camera. Sometimes it is difficult to figure out how the foundation drainage works and where it drains to, and a video inspection may not be enough. Some of this learning may require some extra efforts from specialized contractors, such as camera inspections or dye-testing. Your City may have some of this information which is why it is worthwhile speaking to your municipality first.
In United States, insurance does not cover any flood damages related to “overland flooding”, including flooding that is caused by heavy rainfall, riverine flooding and all other sources of overland flooding. This also includes flooding occurring due to cracks in the foundation, or up through the sump, should any sump pumps fail to operate properly.
Speak directly to your insurer to be 100% certain about the specifics of your own policy when it comes to sewage backups and water damage in general. Typical home insurance, on the other hand, does offer coverage for sewer backup, whether from the storm or sanitary sewer system. This coverage is not necessarily automatic. It is prudent to verify with your insurer that you are insured for sewage backups, and to review the stipulations of that coverage. For example, what would happen to your coverage if you were to make a claim? How does it affect your rates, or insurability? Learn about this aspect of your coverage to understand the implications and know what is covered and what is not. If your home is not insurable due to previous flooding claims, find out what you can do to reinstate coverage, if anything.
As a homeowner, you are responsible for your connections to the municipal systems, and for what you put into those connections. In summary though, a few items that are noteworthy for the average home owner to know and understand:
Sanitary sewage is the only thing that is permitted to be discharged to the sewer, and this means that connections from roof leaders, sump pumps and weeping tiles are all considered illegal connections. Not only do these connections increase your own risk of flooding, they also increase the risk of your neighbors flooding, and increase the occurrence of sewage bypasses to the environment.
There are a number of simple things a homeowner can do to reduce their risk of basement flooding.
Fats, oils and grease can cause a sewage backup because they have a tendency to solidify and accumulate in your internal plumbing, the sanitary lateral or the sewer main. While fat, oil and grease may be liquid when warm, they quickly cool and solidify as they flow through the plumbing pipe network. Flushing down with hot-water generally does not eliminate this risk, it may just get the substance a bit further down into the plumbing system. Your municipality will not take responsibility for any blockage due to fat, oil or grease accumulation and blockage that is found on any portion of the lateral.
While a rainy day may seem like a great time to get some domestic chores done, including doing laundry or running the dishwasher, it does increase flood risk for yourself and possibly your neighbors. To reduce the risk and reduce the load on the sewer system, wait until a few hours after heavy rains to undertake heavy water-use practices in the home. This helps you and your neighbors! This is particularly important if you have a backwater sanitary valve on your sanitary sewer. If the backwater sanitary valve is closed because the sewer is full, you risk flooding your home since your own domestic wastewater will not be able to drain to the sewer main.
The lowest level of your home is your basement floor, and it is at the greatest risk of getting flooded. The basement floor is where water will accumulate first, and anything stored on the floor is at the greatest risk. If you do need to store items on the floor, consider lifting them up a bit on shelving or supports, or using water-tight containers.
A big change in home use over the past 50 years has been the increased reliance on basement space as usable living space. Not only does this mean that basements are finished, but they may also be used as rooms for high-value items, such as recreation rooms or computing/gaming rooms, often equipped with expensive electronics and exercise equipment. In the insurance industry, this is considered to be the primary cause of a significant and consistent increasing trend in the average basement flood-related claim value, which is in the order of $15,000 to $20,000 per claim, although $50,000-$100,000 is not unheard of. This trend indicates that homeowners are either unaware of the risk, or understand the risk and choose to take the risk to utilize the space. As mentioned above, all basements are at risk of flooding. Even making use of all the recommendations herein does not eliminate the risk, it just reduces it. A good example is sewer lateral maintenance. All shingle roofs will eventually leak, all driveways will crack, and eventually, all sewer laterals will fail, and unfortunately, failure of a sewer lateral is usually only detected when wastewater is coming up out of the floor drain. When planning how to use your basement space, this should be taken into consideration.
The following lists some relatively simple and inexpensive measures a homeowner can do themselves to reduce flood risk. If they sound complicated or challenging, you may wish to consider hiring a qualified contractor.
Catch basins are the storm sewer grates located on the street, and they are responsible for storm runoff drainage to the storm sewer. In some cases, you might even have one in your front or back yard. Often, particularly in the spring after snow melt or in the fall when the leaves drop off the trees, catch basin grates can get blocked by debris that accumulates on top of them. This may cause or worsen localized street flooding, which may increase the risk of high groundwater levels and possibly surface flooding of neighboring areas including homes, all occurrences that are not covered by insurance. If you know of a catch basin outside your house on the road or even on your lawn, or neighbor’s lawn, consider taking ownership of it and keeping it clear of debris. This simple activity might save you or your neighbor from flood problems.
As mentioned earlier, while some insurers may offer it as an extra provision to your home insurance policy, in most cases, home insurance does not cover floods occurring from surface-water or ground-water getting into your basement, whether by direct overland routes of via cracks or holes in your foundation walls or floor.
As with anything, foundations deteriorate over time. With this deterioration, and potential construction flaws and differential settling, cracks may form in your foundation, either on the walls or on the floor. When the groundwater level around your home is high, it may submerge these cracks and pressurize them to the point where they leak water. Leakage rates may be minimal, but they can also be substantial, depending in how much water there is near the crack, and how big the crack is. So, just like you get the shingles on your roof replaced, say every 10-15 years, it is also important to maintain your foundation. In many cases, you may be able to simply seal the cracks from inside the basement, without any need to dig. But for larger cracks, or particularly persistent ones, contracting the help of professionals may be required as these may be candidates for more substantial repairs done on the exterior of the house. You may wish to flip through the City’s Yellow Pages for “Foundation Repair”to help find a suitable contractor.
Entry of water from overland flow paths are another form of flooding not covered by insurance. There are many potential overland flow paths, but generally this is referring to any path that allows surface water to get in. Such routes may include service holes into the basement, such as holes intentionally constructed for incoming electrical mains, or natural gas for powering a furnace for example. Routes also include gaps beneath doors, or leakage around aging window frames or window wells, among others. Home owners should take the necessary steps to ensure that all potential overland flow routes are properly sealed, and even better, also ensure that the source of the water at those points be diverted elsewhere by proper site grading. Note that reverse slope driveways and window wells are both forms of overland flow routes that are discussed in further detail later on.
One good way to ensure effective drainage of your roof is to maintain your eaves troughs and downspouts. Ensure they are clear of debris and not partially or fully plugged. Plugged eaves and downspouts may result in water filling up and spilling over and discharging to locations close to the foundation. In addition, blockages allow for water to freeze and expand and break apart the seam on downspouts, such that water may spill out down the wall. A big rainfall is a great time to take a walk around your home, and make sure everything is working as it should. Looking up at a split downspout. This one is due to a blockage from roofing materials, then freezing in the winter. A typical eaves trough, clear of leaves and obstructions.
While standard practice in the 1960’s and earlier, municipalities across the world have recognized that downspouts discharging to a sanitary system serve as significant contributors to sewer surcharging, bypasses and basement flooding. This is because during major rain storms, rooftops generate a considerable amount of run-off, not only in terms of volume, but also in terms of flow rate, since the runoff occurs very quickly off slanted roofs. It is currently illegal to have your roof’s downspouts discharging to the sanitary sewer system. How do you know if this is the case? If your downspouts are entering a pipe that goes below grade, in all likelihood, you have illegal connections and should take the necessary steps to disconnect them. Best practice for downspouts, where feasible, is to discharge downspouts via extensions to a splash pad, and ultimately out to a grassy or otherwise permeable surface where the water can infiltrate naturally. Consider adding a rain barrel to store some of that clean water for watering your lawn or garden! Ideally, where possible, downspouts should discharge as far away from the foundation as possible, or at least a minimum of two meters to a pervious surface such as a lawn or garden. A couple of things to consider:
Controlling the movement of surface water around the home is a critical aspect in keeping a dry basement. Controlling surface water may include consideration for the following:
Rear to front drainage
Drainage from rear yard and back of house wraps around, between homes and towards the street.
Rear yard drains to swale while the front yard drains towards the street.
Different lot grading scenarios:
Probably the biggest factor in keeping your basement dry is having a functioning, efficient and effective foundation drainage system. Foundation drainage will differ from home to home, from neighborhood to neighborhood. In fact, homes built pre- mid-1900’s, may not have any foundation drainage system at all. A plumbing inspection of your home can help you figure this out, although it may not be easy.
Homes with a foundation drainage system may have several components to them:
If you don’t have a foundation drain, and have basement dampness or wetness problems, or recurring flooding problems, consider having a weeping tile installed. This is not an inexpensive procedure, but a good functioning drainage system is essential for keeping a basement dry and usable. Weeping tile systems, as with the sewer lateral, are a feature of the home that requires maintenance. In general, over time, the effectiveness of the weeping tile system will deteriorate, as the pipe ages, or gets plugged with fine sediments, or collapses. Maintenance of the weeping tile system is critical, but unfortunately, it is not easy to get at. The only indication that the system is failing is usually increasing dampness or, more likely, a flood in the basement.
Sometimes built-up sediment can be flushed out without totally excavating the weeping tile. However, if the pipe is collapsing or has deficiencies all around, full replacement may be required. Ideally during replacement, additional access points can be installed to permit future flushing and inspection of the system without excavation. Unfortunately, it used to be common practice to let a foundation drain go directly to the sanitary sewer lateral. The industry now recognizes that this puts otherwise clean water in the sanitary sewer system and this contributes to basement backups and bypasses to the environment. Not only does the extra water from the foundation contribute to these problems, but it also puts the homeowner at greater risk of basement flooding. Disconnecting a weeping tile from the sanitary sewer will help reduce the risk. This involves installing a sump pit and sump pump(s). Ensuring that downspouts and surface drainage promote the flow of water away from the foundation will reduce the dependency on a sump system during rainfall.
Sump Pit and Pumps
Groundwater around the home collected by the weeping tile should go to the sump pit and then be pumped away from the house using one or more sump pumps. This configuration severs home foundation drainage from both the sanitary and storm sewer systems and serves as the best means to control groundwater with the least risk.
Sump pumps need to be sized properly, maintained, and provided with backup power.
The outlet pipe from the sump pump is required, by law, not to go to the sanitary sewer system. The best option is to direct the sump pump to the lawn, where it can infiltrate naturally into the ground. The discharge location should be at least 2.0 meters from the foundation and in no way create adverse conditions on a neighbour’s property. In a nutshell, this water is your own stormwater runoff, and you are required to accommodate it on your own property. Also, be sure that the location you choose to discharge it does not create a health and safety issue on your own property, a neighbor’s property, or on a public sidewalk or road. One example is freeze-up in the winter on a driveway, or worse, a public sidewalk.
In order for your sump pump system to work effectively when you need it, three things are critical:
A backwater sanitary valve is a valve that generally permits one-way flow of water. In a nutshell, it is a valve that closes when the water level rises on the downstream side of the valve, thereby blocking flow in the reverse direction. When built into a sewer lateral, backwater sanitary valves may offer some protection against sewage backups.
Proper installation and placement of backwater sanitary valves is critical, as is the type of backwater valve used. The following points need to be considered:
Maintenance and know-how are critical for backwater sanitary valves to work.
Despite the challenges listed above, when installed properly with adequate maintenance and awareness, a backwater sanitary valve can offer increased protection against sewage backup.
Installing a backwater sanitary valve requires a plumbing permit and a licensed plumber to complete the work for you.
Safety Alert! Gas lines may intersect the sewer line leading to your home. Equipment used to clear sewer lines could damage these intersecting gas lines, leading to possible gas leaks or a serious safety risk. Before clearing a blocked sewer line, to schedule a free inspection to locate underground utility lines.
Nothing but regular inspection and maintenance can protect you against a flood due to a failed sewer lateral.
The sewer lateral is the pipe that connects your homes internal plumbing to the sewer main in the street. It is a vital component to the system, and if it is blocked, or fails, your home will experience a sewage backup. It is considered best practice to have your sewer lateral inspected every 5-10 years or so, generally more frequently the older your home is. Inspection is the only way to observe and identify and address potential problems before a failure causes a sewage backup. Failures are not the only problem. A cracked or leaky lateral that allows the infiltration of groundwater may increase the risk of flooding as well. Call a licensed plumber to see if they can offer this service. Generally, good sewer lateral maintenance will reduce the likelihood of a sewage backup.
While a storm sewer lateral can provide a handy outlet for storm and groundwater, it also serves as an additional connection to a municipal system the storm sewer. A bit different from the sanitary sewer in this regard, a storm sewer is actually designed to be full and surcharge, on average once every 2-5 years. While it provides a handy outlet for downspout and foundation drainage, it also offers an added liability when the storm sewer is overflowing.
If you don’t use it, consider having the storm lateral severed. An ideal spot is near the property line. This means you need to be directing your downspouts and foundation drainage to the lot’s surface for infiltration of your storm and groundwater and experience no excessive water on your property. Severance of the storm lateral will require a permit as well as the assistance of a contractor to undertake the work.
A reverse-slope driveway is one that goes downhill towards the home, rather than downhill toward the road. Reverse-sloped driveways create a significant flood risk as they offer a distinct pathway for water towards the house, from the road. The road is typically part of the “major” storm drainage system – part of the storm drainage system that is used to provide drainage of storm runoff when the pipe system is full, generally every 2-5 years.
Catch basins or drainage grates are usually located just outside the garage door on reverse slope driveways to capture any runoff, snow melt or otherwise from the driveway. However, if the road is flooding and water is coming down from the road, often the catch basin has insufficient capacity to handle all that water. This creates a risk of surface flooding to the home, whereby water can enter the home via the garage or other pathways into the home at the basement level.
A few things to consider:
Altering the drainage of a reverse-sloped driveway requires considerable work and expense, but is very useful in reducing the risk of flooding.
Basement windows are often a weak point in the home’s defense against moisture. Window wells can help in a number of ways. For one, they are likely to improve the drainage around the window to ensure that the windows last longer. And they can help route water to the foundation drainage system, rather than in through the framing or the window itself.