Although record-breaking floods are relatively uncommon in the United States, every year some areas experience significant flood events. These may be due to hurricanes, the combination of winter’s snow runoff with heavy spring rains, stationary or recurring storm fronts, or even tidal waves. Floods can significantly threaten public health, not only in terms of deaths by drowning, but also indirectly through carbon monoxide poisoning, waterborne disease, hypo- or hyperthermia, infected wounds, and electrocution.

When polluted rivers and lakes overflow due to floods, or torrential rains cause sewage systems to overflow, the ground itself can become contaminated with dangerous chemicals or fecal matter. If the flooded area contains crops, those crops will also be contaminated, possibly resulting in high levels of toxic chemicals. Fruits and vegetables that have been touched by polluted flood water can harbor disease organisms such as e. coli or salmonella, in addition to chemicals. In this situation, washing or sanitizing the food item is not effective in removing contamination. The food must be destroyed or widespread illness may result.

Water quality is an obvious issue after a flood, since polluted water can infiltrate groundwater supply, collection tanks, and even rural wells. Use bottled water until you are sure that your water supply is safe. You should not use flood-contaminated water for any reason, not even laundry or baths. If instructed to do so, boil water for one minute and allow to cool before using. Listen to local radio stations (you should keep an emergency radio on hand in a waterproof container) to get advice from authorities on water quality.

Gasoline powered devices such as generators and blowers are often used during cleanup after floods. These devices can be very dangerous if they are used inside, even when doors and windows are opened. Carbon monoxide can build up over time and nearby individuals may not realize anything is wrong until it is too late. If you are cleaning up from a flood, never use a gasoline powered device inside your house or garage, even with ventilation. If you experience symptoms such as unusual sleepiness, headache, or dizziness, get immediately into an open area and seek medical attention as soon as possible.

Hurricanes and other types of severe storms often cause downed power lines in addition to floods. Since water is an excellent conductor of electricity, stepping into flood waters where a power line is down is the same as dropping your hair dryer into your bath water. Electrocution occurs almost immediately. Remember, sometimes you will not see the downed power lines. For this reason (as well as not knowing for sure how deep the water is) you should never enter flood waters unless you have been told by authorities that it is safe to do so.

The presence of bacteria and viruses in flood waters can result in an infection if you have a break in the skin, such as a cut or abrasion. Unfortunately, wounds like these are often sustained during cleanup efforts. Wear heavy gloves and boots while cleaning up after a flood. If possible, the boots should have steel toes and insoles to protect you from dangerous items on the ground. If you are injured, disinfect the wound and apply a dressing along with antibiotic ointment. Do not allow the injured area to touch the water. Also, check your immunization history – if your last tetanus shot was more than five years ago, or if you are not sure, see your health care provider for a booster shot.

Finally, floods can increase the risk of heat-related illnesses (hyperthermia) in the summer, and decreased body temperature (hypothermia) in winter or even in summer. Flood water is often much colder than body temperature, especially if it is related to runoff from mountain snow. If a person is stranded in a flood and spend too much time in the water, their body temperature can drop to dangerous levels. Stay away from flood waters as much as possible, and never drive your car through high water. You could get swept away even with relatively low water levels. During cleanup work, individuals can get overheated and develop heat exhaustion. Make sure you stay hydrated, and replenish electrolytes with a sports drink if you are sweating a lot.

Floods can be deadly weather events, but you can reduce your risk by taking precautions. One of the most important precautions is to be prepared to respond in an emergency. To find out more about emergency preparedness and floods, check out the links below.