Floods and flash floods

Habitat Ready: Disaster preparedness for homeowners

A flood is an overflow of water onto normally dry land, often caused when excessive rainfall or a dam or levee failure causes rivers and streams to overflow their banks.

Some floods develop slowly, while others develop in just minutes. Being prepared and taking mitigation measures, such as building away from floodplains and elevating homes, can reduce the risk of damage and injuries in a flood.

Before a flood or flash flood

  • Review your family preparedness plan.
  • Establish a family communications plan.
  • Assemble a disaster supply kit.
  • Have a family evacuation plan in place.
  • Find out if you live in a flood-prone area and whether your property is above or below the flood stage water level.
  • Elevate your furnace, water heater and electric panel.
  • If time permits, use sandbags to construct barriers to protect your home.
  • Consider installing “check valves” to prevent floodwaters from backing up into the drains of your home.
  • Be familiar with flooding warning signs:
    • Consistent heavy rains.
    • Overflowing rivers and streams.
    • Saturated ground.
  • Know the difference between a flood or flash flood watch and a flood or flash flood warning:
    • Flood watch: A flood is possible. Stay tuned to a National Oceanic and Atmospheric Administration weather radio or TV for more information.
    • Flash flood watch: A flash flood is possible. Stay tuned to a NOAA weather radio or TV for more information and be prepared to leave for higher ground if necessary.
    • Flood warning: A flood is expected or occurring.
    • Flash flood warning: A flash flood is expected or occurring. Seek higher ground immediately.
What’s the difference between a flood and a flash flood?
The distinguishing factor between a flood and a flash flood is the amount of time it takes for the flood to occur. A flash flood occurs within minutes or hours. A flood occurs more gradually.
Flash floods are often more dangerous because they occur with little warning. Their quick nature makes them much more powerful than floods, and they often become raging torrents of water, sweeping away everything in their path.

During a flood or flash flood

  • Listen to a NOAA weather radio for updated information.
  • If time permits, move valuable possessions to upper floors or safe ground.
  • Be prepared to evacuate, and do so immediately if necessary.
  • Do not walk or drive through any floodwaters.

After a flood or flash flood

  • Continue listening to a NOAA weather radio for updated information.
  • Avoid damaged areas, stay off roads and remain on firm ground.
  • Avoid floodwaters. The water may be contaminated.
  • Return home only after local officials declare it is safe. Enter your home with extreme caution. Do not enter if floodwaters remain.
  • Inspect your home:
    • Leave the house if you smell gas or chemical fumes.
    • Check for damage to walls, the foundation, the electrical system and water lines.
    • Clean up spilled medicines, bleaches or other flammable liquids immediately.
    • Notify your insurance company if your home is damaged.
  • Help injured or trapped people. Do not move seriously injured people unless they are in immediate danger of death or further injury. Call for help.
  • Open windows and doors to help dry the house.
  • Check food supplies and drinking water. Anything that has come in contact with floodwater may be contaminated and should be thrown out.
  • Clean and disinfect everything that got wet.
  • Watch out for snakes and other animals. Use a stick to poke through debris.
  • Avoid making phone calls except in serious emergencies. 

Additional resources

Emergency/preparedness information

Current flood/flash flood information

Other information

Landslides and debris flows

Landslides and debris flows are caused by a number of factors, such as earthquakes, heavy rain, volcanic eruptions and poor land management. Because landslides and debris flows occur quickly and with little notice, it is essential to be prepared.

Read more

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