Floodwaters affect a flooded house three ways:
First,
Silt, mud, and unknown contaminants in the water not only get everything dirty, they also create a health hazard.
Second,
Dampness promotes the growth of mildew, a mold or fungus that can grow on everything in the flooded house.
Third,
The water damages materials. Wood can swell, warp, or rot if it remains wet too long, wallboard will disintegrate, electrical parts can short out, malfunction, and cause fires or shock.

The following steps work on all three of these problems. It is very important that they be followed in order.

Lower the Humidity

Everything will dry more quickly and clean more easily if you can reduce the humidity in the flooded house. There are five ways to lower the humidity and stop the rot and mildew: open up the flooded house, open closet and cabinet doors, use fans, run dehuminidifiers, and use desiccants.

Sort Contents and Discard Debris

You have three types of contents in your flooded house that should go to three different places: things you want to save, things you don’t want to save, and garbage.

Drain the Ceilings and Walls

Once contents and debris have been cleared from your flooded house, the next step is to get the water out of the ceilings and walls. How you drain and dry your ceilings and walls depends on what they are made of: wallboard, insulation, wood, or plaster.

Dry the Floor

Air needs to circulate below the floor to dry it out. If the crawl space of your house is flooded, pump it out. Remove any plastic sheets, vapor barriers or insulation from underneath the floor. Be sure to replace them when the floor and foundation of the flooded house are completely dry.

Remember, do not start rebuild and floodproof, until the flooded house is completely dry.