If the water has flooded multiple stories, do not go into a room where the ceiling or floor is sagging, since the ceiling can collapse. If your home is completely under water, you cannot save your possessions.
You may need to travel to an emergency shelter. When entering a dark area, make sure that you turn on a flashlight before entering the area and do not light any matches in case there's a gas leak.
Gas, Water and Electricity
Turn the gas and electricity off for safety reasons. Fortunately, you can shut these off at the meters.
However, do not touch any panel when you are standing in water. Do not go into any rooms that have the electricity on and standing water.
Call your insurance company immediately. The agent will often have various things that you need to do to submit a claim.
Try to videotape or photograph any damaged or lost property.
If the basement is flooded, try to pump out the water. However, do not remove all the water simultaneously, since this can cause the foundation walls to cave in.
Pump out only a few feet a day. You can rent a pump from a hardware store or purchase one if you frequently experience flooding.
Once the water has reached a point where you cannot pump any more water out, use a wet/dry vacuum to remove the rest of the water.
Rent a trash bin. Remove any items that can absorb water and dispose of them in the trash.
Get rid of all food, cosmetics and medicine that came in contact with the floodwater. You can protect furniture legs by wrapping them with aluminum foil.
Make sure that you pin up upholstery. You will likely need to remove the carpet.
However, you may be able to salvage the hardwood floor by running a dehumidifier after you have wet/dry vacuumed what's left of the water. You can also use an air conditioner to remove moisture.
Cut out some of the drywall so that the dehumidifier can dry out the cavities. The heavy moisture can lead to mold growth and water damage.
The dehumidifier can remove a surprising amount of moisture from a flooded building. Try to maximize air circulation by opening windows and operating fans.