wikiHow to Protect a Basement from Flooding

Three Methods:Emergency powerWarning systemsFlood insurance

Your finished basement is your pride and joy. You’ve already spent thousands of dollars and countless hours converting your concrete dungeon into comfortable living space.

The last thing you need is a tidal pool of ground water or sewage infiltrating your new home office or wet bar. A simple flash flood or a cresting creek can easily transform your new carpeting into a massive, moldy sponge.

Your basement isn’t "finished" without some flood prevention steps, actions to protect your home when flooding does occur and an emergency plan to provide for your family's welfare until you can return to your home. You need layers of protection for the adequate safety of your family and property.


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    Focus on prevention. Long before you're in a flooding situation, look around your property for ways to divert rainwater away from your home. Important considerations are extending rain gutter down spouts away from your home and making sure the grade of your yard surfaces slope away from your home.
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    Clean the rain gutters in the spring and after all the leaves have come down in the fall. Blocked gutters will cause all of the roof water to dump directly against your foundation, increasing the likelihood of basement flooding.
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    Extend the rain gutter downspouts well out and away from your home. Do not connect the downspouts to your foundation footer drain tiles or to underground dry wells. This will only cause the roof water to further saturate the ground and cause flooding in your basement.
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    Walk around outside in your yard during a heavy rainstorm. Watch to see if water is ponding next to your home and if surface water is being directed toward your home. If this is the case, seek a local landscaper or excavation contractor for advice on ways to regrade your yard so the surface water is directed away from your home.[1]
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    Provide emergency power. Install an automatic emergency generator to provide electric service for essential circuits like your furnace or electric heat, well pump, refrigerator, septic tank pump and sump pump in the case when power is lost. Without emergency backup power, you may return home to unnecessary basement flooding, frozen water pipes and a flooded septic tank.
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    Install a sump pump. An automatic sump pump should help keep water leakage normal amounts of rainfall from building up in the basement. As long as the sump pump tank has an opening in the lid, the sump pump will act like a huge floor drain and keep the water from getting deep.
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    Install a backup sump pump. The sump pump is your first line of defense against basement flooding. However, the most reliable sump pump available in the industry is still a mechanic device and can fail. A backup sump pump system, preferably with at least a battery-operated pump, configured with a switch device to begin working if the main is out of commission, greatly reduces the chance of flood. Some systems come with additional security features such as an alarm that goes off whenever the battery operated is started.
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    Make an emergency family plan. Plan ahead with your family so that everyone has each other cell phone and other contact numbers. If you live in an area that is prone to historic flooding, plan ahead of time where you'll be able to stay until flood waters subside. Keep in mind that all your neighbors will probably need housing too. As local hotels are usually inundated during flooding events, try to arrange ahead of time with some local family members away from the flooding area to have temporary housing if ever needed.
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    Have flood insurance. Add flood insurance onto your existing homeowner's policy. Flood insurance is provided by the government and is fairly inexpensive. In the USA, if your home insurance agent does not provide flood insurance, contact FEMA (Federal Emergency Management Agency) for local agencies that do.[2]

Method 1
Emergency power

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    Get a propane or natural gas generator. Do not waste your time buying a gasoline powered generator. You will have to be at home at the time of the power outage to start it. You'll also have to keep returning to your home to add gasoline.
    • There is a wide variety of propane or natural gas generators that run automatically when your power goes out. They set up to run once a week automatically to keep the battery charged.
    • You can be at work or on vacation when an emergency occurs. Your automatic emergency generator will assure that all your important electrical circuits have power for heat, sump pumps and refrigerators.
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    Make sure you have a sump pump. It is more important than your plasma TV or a refrigerator. Without it, it's just like the Titanic in an iceberg field: bad.
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    Check to see if your sump pump has backup power or if the battery in the backup sump pump is fully charged. A simple 30-minute thunderstorm can quickly destroy weekends worth of sweat equity – unless your sump pump has backup power.
    • Emergency power comes in three basic forms. Backup battery systems come in different configurations. Some will work for a few hours but some state-of-the-art battery backup sump pump systems will have enough power to keep a basement from flooding under most circumstances. Some systems allow you to add more than one battery to double the duration of the power. A standby generator offers automatic AND long-term protection. It also protects your whole house, but it is more expensive. Since standby generators are also used to keep your beer cold and your TV tuned into the big game keeping your family safe and warm during a disaster you might want to add the protection of a battery backup with the sole purpose of keeping your basement dry.

Method 2
Warning systems

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    Get a warning system. Even if you have backup power, you should be warned that your basement does flood.
    • Home alarm and security companies can provide you with an alert to your cell phone or pager when your power goes out or if your basement floods.
    • Stand alone water alarm units exist that don't require a full security system.
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    Make sure you carry emergency contact numbers for your plumber or electrician in the event of receiving an alert.

Method 3
Flood insurance

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    Check Your Homeowner's insurance. If it only protects you from wind damages, not flood damage, contact your insurance agent or FEMA for advice on how to add flood insurance.
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    Get a separate flood insurance policy to protect your basement from rising tides. Check with your local insurance agent for details.


  • Put a vent or hole in the the basement wall where where flooded water can flow out such as by the basement windows. This can lower the cost of your flood insurance.
  • Install a check valve for backup sewer. Flooding does cause street sewer lines to back up, and could lead back into your home!
  • You can help prevent basement water problems by keeping your rain gutters clean, extending rain gutter downspouts and other routine maintenance.
  • Where the sump pump is, try making the hole deeper so it will collect longer before it floods out onto the floor where your plasma TV is.
  • Be aware that weather isn't the only cause. Make sure your plumbing is good. Make sure your pipes don't leak or burst.


  • Don't underestimate the chances of your basement flooding. This can happen in any home, no matter how well you protect it.

Things You'll Need

  • Generator or a battery operated backup sump pump system
  • Monitoring system
  • Flood insurance
  • Emergency plan
  • Water alarm that sends text messages

Article Info

Categories: Disaster Preparedness