Flood Response: Shelter in Place vs. Evacuation and Water Damage

Flood vs. Flash Flood: Very Different Situations

River and coastal flooding: Usually provides hours to days of warning. The decision space is shelter in place (if elevation is sufficient) or evacuation.

Flash flooding: Can occur within minutes with little or no warning. The response is immediate — get to higher ground now, not after assessing the situation.

Flash floods kill approximately 150 people per year in the United States, mostly in vehicles. The response is always the same and always simple: get out of low areas and away from waterways immediately.

Flash Flood: Immediate Response

If you hear a flash flood warning, a roaring sound from upstream, or see rapidly rising water:

1. Get to high ground immediately. This is not a drill. Do not wait to see how bad it gets.
2. Do not attempt to walk, swim, or drive through floodwater. Six inches of moving water can knock you down. Twelve inches can move a car.
3. If caught in a vehicle in rising water: Get out as soon as the water rises inside the vehicle. Once water reaches door-height, the pressure differential makes it impossible to open the door. Exit through a window. Swim or wade to higher ground.
4. If trapped in a building by rising water: Move to the highest floor. Do not go into a closed attic — you may be trapped. Signal for rescue from windows.
5. Never shelter in a culvert, low-lying bridge, or dry streambed. These fill faster than the surrounding terrain.

River and Coastal Flooding: Shelter or Evacuate

Evacuate if:

• You are in a FEMA-designated floodplain (Zone A or AE) and the flood is forecast to reach flood stage or higher
• You are in a mandatory evacuation zone
• Your home has flooded before in a similar event
• You have mobility limitations that would prevent escape if water rises faster than expected

Shelter in Place if:

• Your home is on elevated ground above the forecast flood level
• You are not in the floodplain
• Evacuation routes would require traveling through flood-prone areas

If Sheltering During a Flood

1. Move all valuables, medications, and documents to the highest floor
2. Turn off electricity at the main breaker if water is entering the home (electrocution risk in floodwater)
3. Do not use the toilet if sewage backup is possible — sewage lines back up in floods
4. Have a way to signal for rescue (whistle, bright cloth from a window)
5. Have a way to cut through the roof from the attic if water rises above the second floor (attic flood trap is a real scenario — keep an axe or hatchet on the upper floor)

After the Flood: Safety Protocol

Before Re-Entry

• Do not enter a flooded building until water has receded and the building has been inspected
• Check for visible structural damage before entering
• Do not enter if you smell gas
• Wear rubber boots, rubber gloves, and eye protection when entering

Inside the Building

Electrical: Do not turn on any electricity until an electrician has assessed. If the electrical system was submerged, assume it is unsafe until inspected.

Gas: Check for gas leaks. If you smell gas, leave and call the gas company.

Structural: Mud and water weigh a great deal. Saturated floors may not support normal loads. Test floors carefully before walking on them.

Flood Water Contamination

Assume all surfaces that contacted floodwater are contaminated with:

• Raw sewage
• Fuel oil, gasoline, and chemical spills
• Bacteria (Leptospira, E. coli, and others)
• Mold spores

Disinfection protocol: Wash all surfaces with hot water and soap, then disinfect with a 1:10 bleach solution (1 cup bleach per gallon of water). This applies to floors, walls, countertops, and any surface floodwater reached.

Mold Prevention

Mold can begin growing within 24-48 hours of flooding. Mold remediation is far more expensive and disruptive than mold prevention.

Immediate actions:

1. Remove all standing water as fast as possible — pumps, wet-vacs, or buckets
2. Open all windows and doors for ventilation
3. Remove wet rugs, flooring, and drywall within 24-48 hours — materials that hold moisture are permanent mold sources
4. Run fans and dehumidifiers continuously
5. Any drywall with floodwater contact should be cut out from the bottom up to at least 12 inches above the highest water line

Insurance Documentation

Photograph and video everything before you start cleanup. Document:

• All damage room by room
• Serial numbers on damaged appliances
• Furniture and personal property
• Exterior damage

Do not begin major cleanup before documenting, but do begin water removal — insurers understand that emergency mitigation is necessary.