Cleaning up Safely after Flooding

Torrential rainfall in the Midwest and Northeast US this week led to flash flooding, filling basements with water and sewage, which can contain hundreds of pathogens. Residents should assume flood waters are contaminated and that exposure to these waters may raise the risk of diarrhea, dysentery, even hepatitis, skin and eye infections and respiratory disorders.

The first step in the cleanup operation is to remove flood water and sewage and dry the affected area. Powerful fans and enhanced ventilation are helpful for drying damp structural surfaces. Meanwhile, it is important to evaluate items contacted by flood waters, deciding what to discard and what to keep. Whenever possible, a disinfecting solution of water and chlorine bleach should be applied to affected surfaces of saved items.

To help prevent disease transmission associated with flood cleanup, the Water Quality and Health Council offers the following tips:

• When using a disinfecting solution to clean up after a flood, remember to:
  • Wear gloves and protective clothing. Do not touch your face or eyes.
  • Change the disinfecting solution often and whenever it is cloudy.
  • Be thorough. Wash and dry everything well.
  • When finished, wash your hands thoroughly with soap and water for at least 20 seconds, even if you have worn gloves.
• If an item got wet, assume it is contaminated.
• Disinfecting works best when all loose dirt and debris are removed first.
• Use a disinfecting solution (3/4 cup regular strength chlorine bleach or 1/2 cup concentrated bleach to one gallon of water) to disinfect walls, floors and other surfaces touched by floodwaters. Keep the area wet for at least two minutes, then rinse thoroughly and dry.
• Carpets and rugs that have been soaked for more than 24 hours should be discarded. If carpets and rugs were soaked for less than 24 hours, evaluate as follows: Carpets that contacted sewage-contaminated floodwater should be discarded. Carpets contacted only clean basement seepage or lawn runoff into a sub-basement, for example, may be dried and cleaned. Washable throw rugs usually can be cleaned adequately in a washing machine. For more information on cleaning flood-damaged carpets and rugs, see this North Dakota State University website.
• When addressing exterior surfaces, such as outdoor furniture, patios, decks and play equipment, keep surfaces wet for 10 minutes (this may mean wetting the surface more than once), then rinse thoroughly and dry.
• Chlorine bleach solutions degrade quickly- be sure to make a fresh solution daily as needed. Unused solution may be discharged into toilet or sink.
• Contaminated clothing should be washed in the hottest possible water with detergent and chlorine bleach if fabric instructions permit.

Joan B. Rose, PhD, is the Homer Nowlin Chair in Water Research at Michigan State University and a member of the Water Quality and Health Council.