Natural disasters that involve water present unique health hazards, requiring extra caution during the aftermath. According to the Centers for Disease Control and Prevention's resource Mold After a Disaster:
After natural disasters such as hurricanes, tornadoes, and floods, excess moisture and standing water contribute to the growth of mold in homes and other buildings. When returning to a home that has been flooded, be aware that mold may be present and may be a health risk for your family.
When assessing water intrusion, it's important to note the three categories of flood water as defined by the Institute of Inspection, Cleaning, and Restoration Certification:
- Category 1: Clean Water. Water that originates from a sanitary source and poses no significant risk from contact, ingestion, or inhalation.
- Category 2: Gray Water. Water has significant contamination and may pose a health hazard if contacted or consumed by humans. (Dishwasher or washing machine overflow, toilet backup without feces, and water from aquariums are in this category.)
- Category 3: Black Water. Water is heavily contaminated and can contain pathogens or toxins. Anyone who comes in contact with or consumes Category 3 water risks health impacts. (Examples of Category 3 water are sewage; floods from sea, river or lake; and winddriven rain from hurricanes.)
What are the pathogens that may be present in flood waters? According to the Environmental Protection Agency's Flood-Related Cleaning Report:
Flood water is often contaminated with pathogens from sewage, farm animal wastes, and wild animal populations, or that occur naturally in bodies of water (IICRC 2006, FEMA 1992, Straub 1993, Berry 1994, Godfree 2005). Although a complete list would be too long to present here, the following biological agents represent the pathogens that can be found in flood water and residue:
- E. coli
- Hepatitis A
In light of the seriousness of water damage in the indoor environment, the following guidelines may help in the aftermath.
10 Guidelines for Safe Cleanup of Water Intrusion
- Understand that time is crucial. Mold grows within 24-48 hours.
- Record details of damage with photographs or videos.
- Prepare for difficult decisions. Border on the side of caution.
- Keep children and pets away from flooded areas. Those entering the site should wear protective gear such as N95 respirator mask, gloves, and goggles.
- Recognize mold. Look for discolored walls or ceilings. Check for foul odors. Does the area smell musty?
- Dry out the building. Open doors and windows when possible. Use fans. See the CDC's fact sheet Reentering Your Flooded Home.
- When in doubt, take it out! Discard porous items that cannot be thoroughly cleaned and dried.
- Pay close attention to and prepare to discard the following: carpeting and carpet padding, upholstery, wallpaper, mattresses, clothing, paper, wood, and food.
- Discard contaminated building materials including drywall, insulation, wood flooring.
- Thoroughly clean all hard surfaces with hot water and soap. There are varied opinions regarding the use of bleach. All agree that bleach must never be combined with ammonia as toxic fumes will be released. It is important to note that while bleach does kill bacteria and viruses, it does not kill mold; it merely takes away the color. Other cleaning agents include white vinegar, hydrogen peroxide, borax, tea tree oil, and liquid detergents.
Helpful Online Resources
- National Center for Healthy Homes' publication Creating a Healthy Home: A Field Guide for Clean-Up of Flooded Homes
- Federal Emergency Management Agency's Eradicating Mold and Mildew