4890 Alliance Drive, Suite 2200, Fairfax, VA 22030
Seamus Mooney, Coordinator
What It Is
Flooding is one of Fairfax County’s most common hazards. Depending on its depth and velocity, flooding can be a nuisance or a disaster. Be prepared for flooding no matter where you live, but particularly if you are in a low-lying area, near a body of water, downstream from a dam, or in other areas known to flood in previous storms.
A Flood Watch means there is a possibility of flooding or a flash flood in your area.
A Flood Warning means a flood is occurring or will likely occur soon. If you are advised to evacuate do it immediately.
A Flash Flood Watch means flash flooding is possible. Be prepared to move to higher ground. A flash flood could occur without any warning.
A Flash Flood Warning means a flash flood is occurring. Seek higher ground immediately; do not wait for instructions.
A 100-Year Flood (or "base flood") is a flood that has a 1 percent chance of being equaled or exceeded in any given year, according to FEMA's flood maps. A base flood may also be referred to as a 100-year storm, and the area inundated during the base flood is sometimes called the 100-year floodplain, which generally correlated to the "Special Flood Hazard Area" where federal flood insurance is required in order to obtain a mortgage. It should be noted that a "100-year flood" refers to the annual probability of such an occurrence, not the predicted interval between such floods.
A 500-Year Flood is a flood that has a 0.2 percent chance of being equaled or exceeded in any given year, according to FEMA's flood maps. The area inundated during a 500-year flood is sometimes called the 500-year floodplain. It should be noted that a "500-year flood" refers to the annual probability of such an occurrence, not the predicted interval between such floods.
What To Do
Sign up for Fairfax Alerts and have a battery or crank powered NOAA weather radio available.
Prepare your home by cleaning gutters and drains.
Decide early whether you will evacuate, and where you will go if ordered to or opt to leave.
Disconnect electrical appliances.
Know if your residence or business is in a floodplain.
Apply for flood insurance. Consider this even if you are not in the 100-year floodplain (the FEMA-designated “Special Flood Hazard Area”) – many recent floods have exceeded the 100-year and 500-year marks!
Learn First Aid.
Refer to "Medical Emergency" hazard pages.
Listen to official information.
If you encounter rising water, move to higher ground immediately.
Do not touch electrical equipment if you are wet or standing in water.
Always stay clear of floodwaters.
Do not drive through flooded roads, even if you have a vehicle with high clearance and even if the water appears to be shallow – “turn around, don’t drown.”
Stay away from downed power lines to avoid the risk of shock or electrocution.
Return home when local officials say it is safe.
Avoid walking or driving through floodwaters.
Do not drink from floodwaters.
Do not drink or wash with water from a flooded household well until it is tested and found to be safe to use.
Eliminate standing water where mosquitoes may breed.
Do not eat any food that may have come into contact with flood water. “When in doubt, throw it out.”
Remove all porous items that have been wet for more than 48 hours and cannot be thoroughly cleaned and dried. These items can remain a source of mold growth and should be removed from the home.
Check in with family and friends by texting or using social media.
The information contained on this webpage was pulled from the Community Emergency Response Guide. More information about this topic may be found by clicking the link below.