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In order to figure out how to stop your basement from flooding and prevent it from happening, it is smart to figure out why they flood in the first place. Basements can flood for a variety of reasons, most often this is due to water coming in from outside sources such as heavy rainfall or broken water lines outside of the home, or from internal issues such as broken plumbing. Here are some common reasons why basements flood:

Poor Drainage Systems

  • Clogged or Inadequate Gutters and Downspouts: If gutters and downspouts are clogged or not properly directing water away from the house, water can accumulate around the foundation and seep into the basement.
  • Improper Grading: The ground around the home should slope away from the foundation. If it slopes towards the house, water will collect around the foundation and increase the risk of basement flooding.

Foundation Cracks

  • Structural Cracks: Cracks in the foundation walls or floor can allow water to seep into the basement. These cracks can be caused by settling, hydrostatic pressure, or other structural issues. Cracks in your foundation create a channel for water to enter a basement. 

Hydrostatic Pressure

  • Groundwater Pressure: When the soil around the foundation becomes saturated with water, the increased hydrostatic pressure will work to push water through any cracks or porous areas in the foundation and push water into the basement. 
  • When the soil around the foundation becomes saturated, the increased hydrostatic pressure can push water through any cracks or porous areas in the foundation.

Failed Sump Pump

  • Sump Pump Failure: Most basements are equipped with a sump pump, a mechanical pump that works to get water out of your basement much in the same way a bilge pump works in a boat. If a sump pump malfunctions or cannot handle the volume of water, the basement can flood. Power outages during heavy storms can also lead to sump pump failure if there is no backup power source.

Plumbing Leaks

  • Burst Pipes or Leaking Appliances: Internal sources of water, such as burst pipes, water heaters, or washing machines, can cause significant flooding in a basement. These appliances can pump out deceptively large amounts of water.

Window Well Leaks

  • Improperly Sealed or Drained Window Wells: Basements with below-grade windows can experience flooding if the window wells are not properly drained or sealed. You most likely will see these wells in newer construction as they are meant to allow people to escape a basement in the case of a fire. These large wells, if not properly sealed or drained create a recipe for a flooding disaster. 

Sewer Backups

  • Blocked or Overloaded Sewer Lines: Sewer backups can occur during heavy rainfall when the municipal sewer system becomes overloaded, causing sewage to back up into homes through floor drains, drains in bathrooms, shower drains, and other entry points.

High Water Table

  • Rising Groundwater Levels: In areas with a high water table, even minor increases in groundwater levels can lead to basement flooding. This is particularly common in areas with heavy rainfall or melting snow.

To mitigate the risk of basement flooding, homeowners can take several preventive measures, including ensuring property is properly graded, maintaining gutters and downspouts so they aren’t blocked, sealing foundation cracks, installing and maintaining sump pumps, and considering backflow prevention devices for sewer lines. Regular inspections and maintenance can help identify and address potential issues before they lead to flooding.