In addition to wiping out roads and buildings, massive flooding such as that seen in Colorado this summer can result in unanticipated hazards from tainted floodwaters. The problem arises when pathogen-laden wastewater and fecal material from animals mingles with floodwater. Disease risks from exposure to waterborne germs carried by floodwater include dysentery and hepatitis as well as skin infection, eye infections and respiratory disorders.
To help prevent disease transmission associated with flood cleanup, the Water Quality and Health Council offers the following tips:
- 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.
- 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.
Disinfecting Private Wells
If the wellhead has been submerged by floodwaters, the well has most likely been contaminated.
If microbial contamination is suspected (if well was flooded or if water is unusually cloudy, odorous or tastes different), immediate disinfection is recommended. If contamination is discovered through water sampling, disinfection is required. Private well water consumers may choose to have their water sampled again immediately after disinfecting to be certain water is safe to drink. Thereafter, periodic sampling can help provide assurance of good drinking water quality.
Consumers of private well water may contact the local health department for advice on well disinfection. This task can be carried out either by ground water professionals or by the homeowner using an array of information resources available from state and local health departments and government agencies. See, for example, the US Environmental Protection Agency’s website, “What to Do After the Flood” at: http://water.epa.gov/drink/info/well/whatdo.cfm
Note: Depending on the local geology, it is possible for an aquifer (underground water-bearing formation) to become contaminated by floodwater. In such cases, disinfecting the well may not ensure safe water. Aquifer contamination by floodwaters usually clears up after a period of time, but until water sampling confirms good water quality, the household served by a private well should disinfect all water used for drinking and food preparation.
Chris Wiant, M.P.H., Ph.D., is president and CEO of the Caring for Colorado Foundation. He is also chair of the Water Quality & Health Council.