[Read: 20 Things You Should Never Buy Used.]
The Centers for Disease Control and Prevention warn that anything that can't be disinfected, which includes carpeting, rugs, mattresses, books, and many toys, should be thrown away. Even dry wall and insulation need to be tossed if they've come in contact with flood waters, which are often contaminated with sewage. (Hard surfaces, such as floors and countertops, can be cleaned with hot water and detergent and then bleach.) The CDC also says clothes worn during cleanup need to be treated as though they are contaminated, and washed thoroughly in hot water and detergent.
Since it's impossible to know where second-hand items have been during flooding, anyone shopping at garage sales or second-hand stores, especially in the areas hit by superstorm Sandy, should avoid purchasing products that might be contaminated, especially if they can't be easily cleaned after purchasing. Used baby toys, for example, should probably be avoided.
The risks are too high to justify the potential savings: The CDC warns that infectious diseases as well as toxins can be spread through flood waters.
Big, expensive household systems, such as those used for heating, ventilating, and air conditioning (HVAC), also need to be thoroughly cleaned after a flood, if not replaced. The CDC warns that HVAC systems that were underwater during flooding can become contaminated and grow bacteria and fungi. The surfaces can be disinfected with a mix of water and bleach; the CDC recommends that homeowners enlist the help of a professional for this task to prevent mold from spreading throughout the house.
The fridge and its contents can be another source of danger. The CDC warns that any food that might have touched flood waters needs to be thrown out. Only canned goods can be salvaged; the CDC explains that labels should be removed, and then the cans washed and dipped in a solution of bleach. Perishable food that has been sitting in freezers or refrigerators without power also needs to be tossed; after four hours, meat, eggs, chicken, and fish go bad.
Those rebuilding in hard-hit areas might also need to splurge on bottled water, at least until local authorities confirm that the tap water is safe to drink. (Parents mixing formula for babies should take extra care to avoid using contaminated water.) In New York City, Mayor Michael Bloomberg said that water coming out of city faucets remained safe to drink throughout the hurricane and its aftermath.
The stress of these unexpected costs can be eased, at least in part, by insurance coverage. However, many people, especially young renters, lack coverage. An Allstate Insurance survey found that 2 in 3 college-age adults have no renters insurance at all.
But even those with insurance can find themselves paying for many unexpected costs after a disaster. Most private policies exclude coverage for flood damage, for example. (Homeowners can get it through the federal government's National Flood Insurance Program, for up to $250,000 for home structures and $100,000 for possessions, and they can supplement that coverage with additional policies through the handful of private insurers that offer it.)
For many of these incidental costs, such as food and carpeting replacement, homeowners will need to tap into their own personal emergency funds--another reason it's so important to have one.