Flooded Basement? Learn the Causes, Prevention, and Solutions

Kenneth Wilson

Trust me; I know flooding is never a fun topic. But unfortunately, homes built partially underground will likely deal with flooded basement instances.

So, if you're wondering: "What causes basement flooding?" ─ you're in luck as we've got you covered. To help you prevent this problem in the future, let's delve into the common causes and what you need to do in such a situation.

7 Common Causes of Basement Floods

Let’s discuss seven of the most common causes why basement floods.

1. Failing Sump Pump

The sump pump is usually installed in a basement or crawlspace (sump pit). Its primary role is to keep the area underneath the building dry and prevent flooding since it removes the water from under the home. (Related: How Long Do Sump Pumps Last?)

Sump pump failure may result from a sudden heavy downpour or an unprecedented power interruption. This may cause groundwater to overflow the sump pit and into the basement. That said, it's crucial to maintain your sump pump regularly. (Related: Six-Step Maintenance Guide To Keep Your Sump Pump Working For Years)

2. Insufficient Weatherproofing

Groundwater collects in places that are frequently exposed to heavy rain, hurricanes, or snowmelt. As such, basement floods can be due to the water rising to the basement level and seeping into tiny gaps or connections. This can be found in between improperly sealed walls and flooring. (Related: Here’s How to Seal Your Home’s Foundation)

To prevent water leaks and floods, all your home's walls, floors, and foundations must be waterproofed during construction. But since sealants can deteriorate over time, leaks may penetrate the seals. So if your basement frequently floods during heavy– it might be a good time to improve the waterproofing.

Installing a basement waterproofing system correctly– including a sump pump and appropriate drainage is crucial to having a dry basement. For best results, it would be best to contact a local waterproofing expert for their services. And the good news is that your home's return on investment (ROI) can be increased simply by waterproofing! (Related: Basement Waterproofing Cost & Consumer Guide)

3. Sewer Backup

A backflow prevention system, usually found in the front yard, ensures that sewage from the city cannot back up into your house. Keep in mind that sewer blockage and overflow can be caused by excessive rain and congested sewers. This will flood your basement if toilets or floor drains are overflowing or overfilled.

Another possible reason is that tree roots may produce a backup in your mainline (sewer line). In this case, the sewer system may need to be jetted to effectively clean the sewer system and prevent unwanted root growth for up to seven years.

4. The Location of Your Home

Sadly, your home's exact location may be why you're dealing with the headache of frequently cleaning up flooded basements. This is particularly true if you reside in one of the following areas:

  • Close to a stream or river that frequently rises (and is prone to flash floods)
  • Low grading lot: If your home is situated on a low point, the yard's slope may encourage water to flow toward rather than away from home.

5. Plumbing Leaks

If you are 100% certain that your residence is not situated in a flooding zone, the following plumbing crises may result in flooding in the basement:

  • A leaky waste line
  • A busted pipe
  • A clogged fitting
  • A sanitary sewer blockage (due to flushing garbage or pipe breaks)

So, when the sewer system is overloaded, sometimes this may cause the water to back into your house through the floor drains, sinks, and toilets.

If you're wondering, how do I know if I have a plumbing leak? First, inspect large amounts of water that appeared too quickly. This will tell you it's not a leak from foundation seepage since it commonly takes time. Leaks from a sewage backup or clogged drains also smell foul and filthy.

Important Note: Flooding from plumbing leaks can be dangerous to your health. If this ever occurs to you, it would be best to contact a local plumber as soon as possible to fix the problem.

6. Failing Downspouts

The primary role of downspouts is to redirect water from the gutter away from your home and foundation. So if the downspout is failing (due to being broken or improper positioning), rainwater may drain towards your basement. Eventually, this may overload your weeping tile.

Homeowners without a waterproofing safety net may fall victim to basement flooding in such cases. Ideally, downspouts must drain at least 5 to 6 feet away from the wall to avoid flooding the basement. A good rule of thumb is to extend the downspouts with the help of one of the outdoor drainage systems, allowing you to discharge water at the proper distance from your property.

7. Clogged Gutter

Lastly, clogged gutters may also cause a basement to flood. Rainwater is commonly drained using a gutter. But if these gutters are close to a tree, they are more likely to become clogged with foreign debris like sticks and falling leaves. As a result, water cannot securely drain from the roof, through the downspout, and outside of your house. (Related: How To Clean The Gutters of your Home Safely)

Overflowing gutters may have excess water run off the roof and down the sides of your house. Eventually, it may collect and find its way into the basement– causing wood rot or foundation damage. If your gutters are regularly cleaned (a couple of times a year), water is less likely to accumulate on your roof. Clogs are also less likely to happen if you install gutter guards.

Tips to Prevent Basement Flooding

The number one tip? Clear your gutters & downspouts. Before anything, remove any leaves or other debris that may potentially block your gutters and downspouts. Keeping the gutters clean is essential for flood prevention since they divert water.

You only need a ladder and a garden hose to clean the downspout from the top. Simply insert the hose into the downspout's opening to clear the debris. Always manually clean out the bottom opening before cleaning the top of the downspout. You can also buy corrugated plastic tubes to extend your downspouts, so they drain sufficiently far from the foundation. Any hardware or home improvement store should have them.

Here are some additional steps to lessen the chances of water crawling into your basement.

  • Your basement will remain dry if cracks in the walls and floors are sealed. Think about adding a french drain, window well drain, or sump pump as a basement waterproofing system. A professional can guide you on the ideal system for your home. Also, keep your gutters clear, and watch pooling water on the sides of your home.
  • Consider investing in a battery-powered sump pump as a backup drainage system. These backup systems will turn on if your primary sump pump runs out. Also, moving electrical appliances, such as washing machines, away from flood-prone places in your basement may lessen the risk of electrical hazards.
  • Make sure all downspouts drain 5 to 6 feet away from your external walls and clean your downspouts regularly. If the downspouts are too short, you can use extensions. Check that downspouts drain rainwater at least six feet from your home's exterior walls.
  • Assess the grading in the area around your property. To assist in rainwater naturally draining away, the ground should slope away from the foundation. Plant native trees and shrubs all over your property to absorb excess water.
  • Find out if a weeping tile system was used to build your house. As the system ages, repair or replace the perforated pipe that encircles your foundation. Make sure any shallow ditches that surround your property are clean and unobstructed.
  • Once a year, get your water heater and plumbing maintained. To help avoid frozen pipes, keep your thermostat set at 60 degrees or above and open the doors to your under-sink cabinets.

What to Do if Your Basement Floods

Here are some actions you may take when water crawled into your basement.

  • After the basement flooding incident, contact your insurance company to determine what your homeowner's policy covers. If you move during the process, your living expenses might be covered.
  • Always have a list of local plumbers at home. Call one as soon as you discover a plumbing leak, and if a busted pipe is to blame for the flooding, don't forget to turn the water off.
  • Prevent electrical risks by taking the proper measures to clean a flooded basement safely. Until you are entirely sure that all your electrical items have completely dried up, avoid touching them.
  • Gather your safety gear home, including knee-high boots, rubber gloves, a long-sleeved shirt, and a mask. Wear these before turning off the gas and electricity. Find a wet vacuum, sump pump, mop, and bucket to help remove the water.
  • Remember that a post-basement flooding cleanup can be dangerous. Any missed water can lead to mold. If you'd instead leave it to a professional (which is undoubtedly the best choice), contact a local water cleanup and removal company. (Related: Mold in Basement: The Causes & Solutions Homeowners Need to Know About)
Kenneth Wilson
September 10, 2022
Contractor Tips, Interior

Kenneth Wilson

Retired contractor. Currently residing in Southwest Florida. Now in semi-retirement, I write and manage this blog focused on helping home owners make savvy decisions when it comes to finding contractors and getting their projects done. I also operate remodeling design service for homeowners.

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