8 Causes Of Basement Flooding After Rain

This article will help you answer a question – Why do basements flood?

Basements can be nice, cozy places where you can spend some alone time or get some work done. However, they are prone to all sorts of moisture problems, and flooding is one of the major ones.

Why Do Basements Flood?

There are many causes of basement flooding, and you’re probably wondering how all that water got inside.

Do you know why your basement floods when it rains?

Keep reading to find out!

Understanding what causes your basement to flood in the first place will help you prevent it from happening again.

Why is my basement flooding? Here are some of the most common causes.

Cracks in foundation:

Cracks in the foundation of your home can occur as a result of hydrostatic pressure. This is when groundwater pushes against it persistently over time until it starts to give in.

Cracks can appear in different sizes, but no matter how small or large, groundwater can pass through and make its way into the foundation, then into the basement.

The larger the crack, the larger the volume of water seeping through per second.

Over time, an accumulation of water through the cracks in your foundation will flood the basement.

Open or leaking windows:

The worst time to have a crack in your basement windows is during the rainy season.

A heavy rainstorm splashing across a leaking window can only spell disaster to the integrity of your basement, as rainwater will surely seep through the window cracks and eventually flood your basement.

The case may be that your basement windows aren’t even cracked, you may have just been careless enough to leave them open during the time of the heavy rains, and large volumes of water made their way in and flooded your basement.

Absence of good drainage systems:

Heavy rains will give your yard a thorough wash, but that is hardly a problem if you have good drainage systems installed.

Gutters and drain pipes collect large amounts of water and channels them away from your foundation, into the main sewer system.

However, if you do not have a drainage system installed, rainwater will remain to stand and can pass through your foundation and eventually into your basement.

The level of flooding your basement will experience as a result of this is dependent on the intensity of the rain.

Clogged drains:

Having clogged gutters and pipes is just as bad as not having installed a drain system at all.

This is because groundwater cannot flow properly through a gutter that has been compromised by stones, sticks, birds nest, leaves, and other forms of debris.

In this scenario, the water will overflow and continue to rest along the foundation, until it slowly creeps into your basement and floods it.

A tilted landscape:

In the absence of a good drainage system, a landscape that is tilted towards the direction of your foundation can be disastrous.

When heavy rains fall or large amounts of snow melts, the water will flow towards the direction where the yard is tilted. In this case, it’s your foundation.

The water will keep pressing against the foundation thanks to the angular advantage the tilted land offers, and will eventually make its way into the basement.

Internal leakages:

It would be wrong to assume that basements can only flood due to outdoor factors. In some cases, it’s the indoor factors that actually cause all the problems.

One of such factors is leaking pipes or plumbing.

This could be from your kitchen, bathroom, or laundry system.

Poor basement sealing:

During the construction phase of a home, the perimeter of the foundation should be properly sealed so that water cannot seep through and get into the basement.

If the foundation wasn’t properly sealed at the initial stages, then water will continue to flow through the passageways and flood your basement.

A malfunctioning sump pump:

Sump pumps are electronic devices that are meant to pump water away from the basement when the sump pit gets full. This action is usually automatic, and it is triggered by a built-in sensor.

The sensor detects when the water levels are too high, and triggers the engine to start, and this is when the machine begins pumping the water out of the basement, and into the main sewer system.

If the sensor malfunctions, then it would not be able to detect high water levels and signal the engine to start. The result of this malfunction would be a flood in your basement.

The case may even be that your sump pump is working perfectly, but was disconnected from its power source, hence the reason it didn’t pump when the water levels rose.

Downspout distance:

The distance between your downspout and your home can play a huge role in basement flooding.

Ideally, your downspouts should extend a minimum of 10 feet away from your home. Unfortunately, a lot of homeowners don’t fancy their downspouts extending so far, which is why they keep facing the same basement flooding issues.

Well, if you’re serious about keeping your basement from flooding, then you should install your downspouts at that distance. This will help to effectively discharge the water coming from your roof far away from your house.


If you have a lawn, it means there will be a lot of sprinkling from the irrigator. And if your lawn is situated very close to your house, it means that all the water traveling from the irrigator to your lawn will be sitting too close to your foundation.

This is not a pretty scenario, especially if you’re trying to prevent basement flooding.

The ideal setting would be to build your lawn far away from your foundation to spare the foundation of all that irrigation water.

If you’ve already built your lawn close to your house and you don’t want to change its position, then have the installer of the irrigation system limit the amount of water being dispersed close to your house.

An extra tip is to ensure that the irrigation system has a built-in rain gauge. This will stop the system from automatically turning on after there has been plenty of rain.

There’s no point watering the plants after it just rained, that will be too much water for your foundation to bear.

Dealing With What Causes Basement Flooding

As you now have a fair understanding of the causes of basement flooding, you can follow the tips below to prevent it from happening.

Tip 1: Install a sump pump

If you don’t already have a sump pump, then you should visit a home improvement store near you and buy one. They are relatively inexpensive and they can be very helpful.

Ensure that your sump pump is in good working condition at all times by carrying out regular maintenance practices.

Tip 2: Re-slope your yard

Having your yard tilt towards your home means groundwater will move in that direction and lodge there.

If you’re looking to take the pressure off your foundation, then I advise you to redo your landscape and have it tilt away from the home.

By doing so, rainwater will flow away from the foundation, and not towards it.

Tip 3: Properly install your downspouts

A properly installed downspout sits 10 feet away from the home, to channel the water coming from the roof as far away as possible.

Tip 4: Unclog your gutters

Clogged gutters cannot have free-flowing water, and all the overflow will rest on the foundation walls, and eventually seep into the basement.

For your gutters to flow uninterruptedly, you need to ensure they are free of debris such as sticks, leaves, fragments of birds’ nests, and junk.

Doing regular clean-ups and checks on your gutters will prevent a clog, which will, in turn, reduce the chances of an overflow into your basement.

Tip 5: Seal your foundation

Since most basement flooding is caused by water seeping through the foundation, it would be a good idea to reinforce the perimeter.

There are exterior concrete sealants you can use to do this, either by yourself or with the help of a professional.

Once the foundation is sealed, the chances of groundwater seepage will be significantly reduced.

Tip 6: Fix internal plumbing

If there are leakages in your kitchen, bathroom, or laundry room, then your basement is still prone to flooding. For this reason, you should call a plumber to come and inspect all the plumbing systems in your house.

All plumbing issues should be fixed accordingly to avoid leakages and flooding.

Tip 7: Fix window cracks

The rains won’t stand a chance against your basement windows if there are no compromises. Ensure that they are free of cracks so the water won’t creep through in the rainy seasons.

Be sure to always keep your basement windows sealed when you are leaving your house or going away for a while.


Basement flooding can be avoided once you understand why they get flooded in the first place. I hope this article has provided you with all the information you need regarding the matter.

Here is all about basement flooding cleanup.

Thanks for reading!

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