How to Prevent a Mold Outbreak After Your Home Floods

Act fast: Mold can develop within 24 to 48 hours

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An illustration of a flooded basement. Illustration: Getty Images

Storm season brings the potential for heavy rains and serious flooding. Along with that comes the threat of mold outbreaks, which can ruin home furnishings and pose health problems for people with allergies, asthma, and compromised immune systems.

To keep mold in check, you should attack the problem within 24 to 48 hours. Follow the advice from federal safety experts below.

The Environmental Protection Agency says you can tackle minor mold outbreaks (small areas of 10 square feet or less) using a little elbow grease and a mixture of detergent and water.

More on the Storm Aftermath

But people whose homes have been soaked or affected by dirty water are likely to need help from a professional mold remediation service, especially if their heating and/or cooling system has been affected.

The agency doesn’t rule out the use of bleach or other biocides for larger problems. “Make sure you use fresh bleach,” says James E. Rogers, Ph.D., director of food safety research and testing at Consumer Reports, noting that household bleach will lose its potency over time.

And never mix bleach or bleach-containing products with ammonia or ammonia-containing products because the combination can create toxic fumes that cause respiratory problems.

Tips for Safe Mold Cleanup

Dealing with mold is not a do-it-yourself project if you have respiratory problems or are immunocompromised, Rogers says, because both the use of bleach and the prolonged exposure to mold can be harmful to people with certain health problems.

If you don't suffer from such health problems, follow these cleanup tips from the EPA, Centers for Disease Control and Prevention, and Occupational Safety and Health Administration.

  • Clean up and dry out the building as quickly as possible. Open doors and windows, and use fans and dehumidifiers.
  • Remove all porous items that have been wet for more than 48 hours and that cannot be thoroughly cleaned and dried. These items can remain a source of mold growth. Porous, hard-to-clean items include carpeting and carpet padding, upholstery, wallpaper, drywall, ceiling tiles, insulation material, some clothing, leather, paper, some wood and wood products, and food. Removal and cleaning are important because even dead mold can cause allergic reactions.
  • Clean wet items and surfaces with detergent and water to prevent mold growth.
  • Temporarily store damaged or discarded items outside your house until insurance claims can be processed.
  • For mold that’s caused by floodwaters and can’t be removed by the detergent solution, use a mixture of 1 cup of bleach and 1 gallon of water.

If floodwaters have affected your heating or air conditioning, don’t turn it on. You’ll need help from a qualified professional, the CDC says. All surfaces of a heating, ventilation, and air-conditioning (HVAC) system and all its components that were submerged during a flood are potential reservoirs for dirt, debris, and microorganisms, including bacteria and mold. In addition, moisture can collect in areas of HVAC system components that were not submerged (e.g., air supply ducts above the water line), and this also can lead to the growth of microorganisms. That’s why all components of the HVAC system should be thoroughly inspected, cleaned of dirt and debris, and disinfected by a professional.

Wear Protective Gear

If you are attempting your own cleanup, the EPA recommends that you wear the right gear. While you don’t have to wear a complete hazmat suit, you should cover your eyes, nose, and hands when attempting mold remediation. You should also wear a long-sleeved shirt and long pants, and work shoes. Here’s how to limit your exposure to mold and mold spores.

Wear a respirator. A dust mask or handkerchief will not protect you because mold can pass through it. Instead, use an N-95 respirator, available at many hardware stores and online. (They cost about $12 to $25.) Some N-95 respirators resemble a paper dust mask with a nozzle on the front; others are made primarily of plastic or rubber and have removable cartridges that prevent mold spores from entering. To be effective, the respirator or mask must fit properly, so carefully follow the instructions that come with it.

Wear goggles. To avoid getting mold or mold spores in your eyes, wear goggles that do not have ventilation holes.

Wear gloves. Avoid touching mold or moldy items with your bare hands. Long gloves that extend to the middle of the forearm are recommended. When working with water and a mild detergent, you can use ordinary household rubber gloves. If you are using a disinfectant, a biocide such as chlorine bleach, or a strong cleaning solution, you should select gloves made from natural rubber, neoprene, nitrile, polyurethane, or PVC.

When you’re done, there should be no visible mold and no moldy odors, although there may be some collateral staining and cosmetic damage. Once the area is clean and dry, you can paint over that.

Use a Dehumidifier

If your basement is usually damp, use a dehumidifier to keep the moisture content down. We recommend buying a model with a large tank that can collect 60 to 70 pints of water per day, so you don’t have to empty it as often. Below, in alphabetical order, are three of our top-performing dehumidifiers. For more choices, see our complete list of recommended dehumidifiers.

Mary H.J. Farrell

Knowing that I wanted to be a journalist from a young age, I decided to spiff up my byline by adding the middle initials "H.J." A veteran of online and print journalism, I've worked at People, MSNBC, Ladies’ Home Journal, Good Housekeeping, and an online Consumer Reports wannabe. But the real thing is so much better. Follow me on Twitter.