Information Courtesy of FEMA | www.fema.gov

Before a Flood

To prepare for a flood, you should:

Avoid building in a floodplain unless you elevate and reinforce your home.
Elevate the furnace, water heater, and electric panel if susceptible to flooding.
Install "check valves" in sewer traps to prevent flood water from backing up into the drains of your home.
Construct barriers (levees, beams, floodwalls) to stop floodwater from entering the building.
Seal walls in basements with waterproofing compounds to avoid seepage.

The smartest thing you can do to prepare for floods is purchase flood insurance.