Basements are by definition the base of your home, built either partly or entirely underground. This naturally means they are prone to flooding, even in dry weather. Gravity is typically at fault here. Gravity works hard to push water from the high ground to low, and when there is a room underground, there is a consistent likely chance of flooding.

But why does my basement flood when it rains? My basement, your basement, their basement, anyone's basement can flood, even if it never has before. There are a lot of factors involved, and any one of them can create severe water damage from basement flooding.


The answer to ‘why does my basement flood when it rains' is complicated as there are a plethora of reasons behind basement flooding. If you do experience water in your basement, it is crucial that you find the source and fix the problem before it gets worse. Remember, it only takes a cup of water to damage your home.

While flooding can happen in dry weather, it is more common in wet. If you experienced flooding for the first time, or it is a consistent problem, there are several areas to look at first.

  • Water Pooling - The main problem is water pooling around the foundation. Gravity wants to pull that water downward, and if there is a way for it to enter the basement, it will. If your home lacks adequate grading, or it suffers from clogged gutters and downspouts, water will run down the walls of your home and your property to gather at your foundation.
  • Foundation Drainage - If you have a foundation drainage problem, you can suffer from flooding. Typically, houses are built with some form of drainage system around them to move water away from the foundation and basement. If this has failed or wasn't built into the property for some reason, any cracks and holes in the walls will allow this water into the basement. But regardless of whether or not there is a drainage system, or whether it is working or not, if there are cracks in your basement walls, water will enter during heavy rains. The risk of flooding through cracks increases without proper grading or downspout extensions.
  • Sump Pump - Sump pump failures are also of concern. If you have one, check on it frequently to ensure it's working correctly or at all. Sump pumps are designed to pump excess water away from the foundation. If the sump pump fails during a torrential downpour, or if you lose power and it shuts off, groundwater can enter the basement through the sump pump and flood the basement.
  • Sewer Backup - Another frequent source of basement floods is a sewer backup. If the city sewers are filled by a rainstorm and begin overflowing, sewage can back up into your home. If the sewers are filled beyond capacity, sewage will flow towards your house and could enter through a floor drain or toilet, flooding the basement.

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If your basement floods, even for the first time, there is a source and a solution. Once you know what the cause is, you can work on fixing the entry point to prevent future flooding.

  • Grading - If you have improper grading around your home, find a landscaper skilled in grading to resolve the issue or try a DIY approach. Shovel compacted soil along the length of below-grade walls to form a two-inch-per-foot slope around your foundation. Add some topsoil, mulch, and plants to make the slopes attractive.
  • Gutters and Downspouts - If your gutters and downspouts are clogged with leaves or other debris, clear it out. Gutters have the specific purpose of water diversion, so keeping them clean is paramount to flood protection. If your downspouts aren't draining far enough away from the foundation, buy some corrugated plastic tubes to extend them further. They are found at any hardware or home improvement store.
  • Foundation Cracks - Cracks in the basement walls are dangerous. They are the perfect entry point for groundwater, and unfortunately, they will never get better on their own, only worse. The safest option is using a specialized basement waterproofing professional to seal the cracks.
  • Sump Pumps - Sump pumps can fail at any given time, so monitor them carefully, especially during dry weather. You want to know whether or not it is working before it rains, or you're looking at probable flooding. There are professionals who can help repair a broken sump pump, and always check if it's still under warranty. Also, it's a promising idea to install a backup power source. The electricity likes to fail at the worst possible times, and a backup power source can save your house.
  • Basement Floor Drains - There is nothing you can do to prevent the city sewers from overfilling, but you can protect your basement floor drains with a one-way drain plug. They are installed below the drain grate and prevent sewage from entering the basement. Relatively inexpensive, you need to check the plug regularly to keep it clean of debris that would prevent it from working.


If you're surprised by and/or overwhelmed by your basement flooding problem, you might not know where or how the water is getting in. Luckily, there are basement waterproofing professionals you can schedule an appointment with. They assess your property and your basement to evaluate the water issue and determine where it is entering. They can seal cracks, install a sump pump and more. Find a specialist and schedule an appointment today.

Call 877-957-5670 to schedule an appointment with an AdvantaClean basement waterproofing specialist today!

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