Basement Drainage & Basement Flooding

If you live in an area with a municipal sewer system and your home’s basement drainage system is tied into that system, you could be in trouble when a big storm hits!  Most municipal sewer systems in Canada are only designed to handle storm water from storms that happen once every five years (20% chance) with older systems only capable of draining water from storms that happen once every two years (50% chance)!

Basement Drainage Flooded Basement

Sewer Back-Up in Finished Basement

When these kinds of storms hit, sewer systems get overloaded which prevents yourbasement drainage system from draining causing your basement to flood.  If you’re lucky, you’ll get a swimming pool in your basement that you didn’t bargain for, and if you’re not, you’ll have a sewage treatment plant in your basement!

Waste water, whether it’s sanitary or storm, get to their respective sewer main under the street via a sewer lateral that runs from your home to the sewer main.  Laterals often collapse over time, especially with poor quality pipes that were used in the 60’s and earlier.  Tree root infiltration into residential laterals in another common problem, especially in homes with older sewer laterals reducing the capacity of the lateral and trap solid waste.

There Are Three Common Types of Municipal Sewer Systems:

Sanitary Sewer:  is for collecting household plumbing waste from sinks, toilets, showers and typically does not carry any surface water.  Unlike in the past, municipalities now treat waste water from the sanitary sewer system before it is discharged. Almost every municipality prohibits clean groundwater and surface water from being introduced into the sanitary sewer system due not only to the cost of treating clean water, but the reduction in the system’s capacity that adding clean water causes.

Storm Sewer:  collects surface water during rain, snow melt and storms.  Water from storm sewer systems are not always treated and often run directly into lakes, rivers, etc.

Combined Sewer: are typically found in older cities and sections of older cities.  They collect the household sanitary waste and storm water as well.  Back in the day this waste water was not treated and was dumped directly into harbours, lakes, rivers and so on.  Most municipalities with combined sewer systems have embarked on massive public infrastructure projects to separate combined sewer systems into two separate systems; Sanitary and Storm.  In areas where this hasn’t been done, many municipalities have passed by-laws prohibiting household surface water from foundation drains, sump pumps and downspouts from being discharged into the combined sewer system.

Municipal Requirements

Older homes often have their basement drainage system tied into the sanitary sewer system or a combined sewer system.  Most municipalities prohibit clean groundwater and surface water from being introduced into these systems.  Existing homes with the original basement drainage system tied-in are often grandfathered in; however, a lot of municipalities give incentives to homeowners to disconnect from these systems.  Replacement of the basement drainage system is often not grandfathered and therefore illegal to tie a replacement basement drainage system into either a sanitary or combined sewer system.

If you have to replace your existing basement drainage system, consult with your municipality to find out what you can do and what you can’t.  In many cases, a sump pump is required to mechanically lift groundwater from the basement to the surface on the outside.  If you have a contractor that doesn’t know your municipally requirements, don’t hire him!  Even worse, if they do know the requirements and choose to cut corners and disobey the law, run!  What does that tell you about their character and integrity?  About the likelihood of them honoring your warranty if they even provide one?

So What Can You Do To Protect Your Home From Flood Damage?

  1. Have a licensed plumber install a back flow preventer (backwater valve) on your sanitary sewer line if you don’t already have one.
  2. Disconnect your downspouts from your perimeter drain and sewer system.
  3. Disconnect your basement drainage system from the sewer system.
  4. Install either a new basement drain that discharges to a low area or
  5. Install a sump pump to mechanically lift water from your basement to the surface.  A battery powered back-up pump is highly recommended to be installed any time a sump pump is installed.  A battery powered back-up will protect you from not only power outages, but mechanical failure too.
  6. Ensure proper lot grading and drainage around your home.
  7. Hire a Foundation Waterproofing & Drainage professional to conduct a thorough investigation of your basement drainage system.
  8. Hire a licensed plumber to do a thorough investigation of your home’s plumbing system and especially your sewer lateral.


Basement flooding is a serious problem, having surpassed fire damage as the #1 cause of loss in Canadian homes.  In order to have a dry and flood-free basement, your home requires a well-designed, properly functioning drainage system to drain ground and surface water from around your home.

Have your basement drainage system inspected by a professional, and have your basement drainage disconnected from the sewer system and either install a new drain that uses gravity to drain to a low area or install a sump pump to lift the water out of your basement.  And don’t forget the back-up pump!


Water infiltration into your basement through the floor can be a serious problem causing significant damage to your home. Waterproofing basement floor is the best way to prevent problems. Ideally, this would be done during construction, but often is not. If you need to waterproof basement floor after the home is built, first, you must understand how and why water gets past your basement floor into your basement. Water can enter your basement by coming through:

• Cracks in the floor due to hydrostatic pressure
• Floor/Wall joint due to hydrostatic pressure
• Capillary action
• Vapour transmission due to differential
• Condensation due to a cold floor and warm, humid air in the loving space.

Waterproofing Basment Floor

Water Flooding Basement through the basement floor

Hydrostatic pressure is a technical term for water pressure. Simply put, the force of gravity exerted on a liquid at equilibrium; the weight of water bearing on an object. This happens when you have a high water table and insufficient drainage around the bottom of your foundation. The water table on the outside of the foundation will rise higher than the basement floor level causing the water trapped beneath the floor to come under pressure. As pressure builds, water will force its way into your basement through cracks in the floor and the floor/wall joint.

Capillary action is when water is “drawn” upward, against the pull of gravity through narrow tubes in porous materials called “capillaries”. Your concrete basement floor is porous and if the water table rises to come into contact with the underside of the slab, water will migrate through the floor slab due to capillary action causing a wet floor.

Vapour Transmission occurs when moisture migrates from areas of high humidity to areas of lower humidity. The soil beneath and around your foundation is at 100% humidity and as we learned above, the concrete in your home is porous and when you combine that with basement humidity between 50-65%, moisture will naturally move from the soil through the concrete into the living space without a vapour barrier.

Condensation often occurs in the summer in un-insulated basement floors. At a soil depth of 2.45m (8ft), the soil is 10˚C (53˚F) even in the summer! This cold soil keeps an un-insulated concrete floor cold. You’ve probably noticed this walking around on our bare feet. When hot, humid summer air comes into contact with the cold floor, it condenses leaving water behind like water on the outside of a glass of ice water on a hot summer day.

There are numerous ways to correct these problems and prevent them in the first place. Over the past 40+/- years an asphalt based coating has typically been applied to the outside of foundation walls as a damp proofing material to prevent vapour transmission through the walls. Spray applied damp proofing is not practical to use on a basement floor so instead, polyethylene sheeting is often installed on the sub-soils beneath the basement floor has been used over the past 30 + years as a vapour barrier to eliminate vapour transmission through the floor and minimize capillary action. Perimeter drains or footing drains as they’re sometimes called drain water away from the bottom of your foundation, lowering the water table minimizing capillary action. Over the past 25-30 years, new homes have had to have air exchangers installed which remove heavy, moist air from the basement and exhaust it to the outdoors helping to reduce condensation on the floor. To further help reduce condensation, extruded polystyrene (Styrofoam) insulation is installed beneath the concrete floor to act as a thermal break in order to help keep the floor temperature closer to room temperature, further reducing condensation.

Waterproofing basement floor is an important to the livability and enjoyment of your home. If you are considering waterproofing your basement floor, you should contact a professional to come to your home to provide a consultation and come up with a plan that’s specific to your home.



Unfortunately basement flooding is a common occurrence in many parts of Canada and can cause significant damage to your home ruining flooring, drywall and your belongings not to mention the risk of unhealthy mould growth.  Dealing with basement flooding and the damage it causes can be very stressful for a homeowner.  And, if left unrepaired, can be very expensive!

Wet Basement, Basement Flooding

Basement Flooding

How Serious Is Basement Flooding?

Basement flooding is a serious problem having surpassed fire damage as the #1 cause of loss in Canadian homes. There are many negative consequences associated with basement flooding, above and beyond the inconvenient mess and disruption of household routine. Research cites the following impacts:

  • Chronically wet houses are linked to an increase in respiratory problems.
  • Frequent occurrences of basement flooding can result in long-term damage to the building and equipment that may not be covered by insurance.
  • Insurance rates may rise to compensate for repeated basement flooding claims, and/or the minimum deductible may be increased significantly.
  • Property value may depreciate because the basement is prone to frequent flooding.

Before appropriate measures can be taken, it is important to identify the causes of basement flooding. These range from problems originating in the individual dwelling to problems associated with the municipal sewer systems that serve entire communities.

Why Do Basements Flood?

Water can enter your basement for a number of reasons. Water in your basement is most likely to occur during periods of heavy rainfall, or when snow is melting rapidly during a spring thaw. In these cases, your basement can be wet because of:

  • A crack in your home’s basement walls;
  • Poor lot drainage and landscaping;
  • Windows too close to grade without window wells and properly functioning drains;
  • Failure of the weeping tiles (foundation drains) causing hydrostatic pressure and water to come in through cracks in the floor and the floor/wall joint; and
  • Overflowing eavestroughs or leaking/plugged downspouts.

Basement flooding may also occur because of:

  • A blocked connection between your home and the main sewer in the street;
  • A back-up of wastewater in the sewer system (or a combination of wastewater and rainwater from the sanitary or combined sewer system); and
  • Failure of a sump pump (in some areas) used to pump weeping tile water.

Basements are also vulnerable to natural river flooding disasters, but these cannot be addressed by individual homeowners.

Basement flooding is a serious issue that is becoming more and more prevalent.  It is something that every homeowner should take seriously and take action to prevent.  Regular inspection of your foundation and plumbing is critical as is maintaining proper lot drainage and grading.

Wet Basement – Get on the right trac with the PERMA-TRAC™ System!

Wet Basement


A wet basement can be a big problem for home owners.  From the emotional toll of having personal property damaged to the physical toll of having to clean up water, to the expense the damage causes.  Basement leaks are not usually planned or budgeted for, often making their repair a financial burden.  PERMA-DRY®’s PERMA-TRAC System is a permanent, cost effective solution to many basement leak problems.

Typically used with concrete block or stone foundations, the PERMA-TRAC™ System is designed to capture water that leaks into your basement through the joint where your floor and wall meet and also through cracks in the mortar joints.  Installed on the inside of your foundation at the floor/wall joint, the PERMA-TRAC™ System, then re-directs the captured water to an existing or a new drain.

Because the PERMA-TRAC™ System is installed on the inside, installation can be done any time of year in any weather condition without costly, messy and environmentally un-friendly excavation!  Not to mention the fact that most traditional exterior repairs can take a week or more to complete and then often take years to get your property back to where it was before the leak.  Most PERMA-TRAC™ installations can be installed within a day or two, allowing you to get back to life!

The PERMA-TRAC™ System is also warranted against leakage for as long as you own your home!  And, if you sell, the warranty can be transferred to a new owner.

The PERMA-TRAC™ System is just one of PERMA-DRY®’s industry leading wet basement solutions.  Top find out more, or to find the PERMA-DRY location nearest you, go to .