Delaware's Division of Public Health (DPH) advises Delawareans that all floodwaters can contain disease-causing organisms such as viruses and bacteria. If any part of public or private water supplies is flooded, the entire system is in danger of being contaminated and should not be used for cooking, drinking, washing or bathing. Delawareans in or near areas that have flooded should not drink their water until officials notify them that it is safe to do so. The causes of contamination include sewage or septic system back-ups in homes, businesses or floodwaters, dead animals, chemical run-off and other debris.
This type of contaminated water is commonly referred to as brown or black water. Materials contaminated with floodwater present an acute health risk if not properly cleaned or discarded.
Human waste contains many organisms that have the potential to cause disease. Even if they are not ill, people can carry the organisms that cause disease and transmit them through their feces. Viruses such as Hepatitis A, which causes liver disease, are commonly found in wastewater. Other viruses present in wastewater may attack the central nervous system, skin, or the heart.
Escherichia coli (E. coli) is a common type of bacteria found in feces that is used to monitor for fecal contamination of water supplies. Bacteria have the potential to cause intestinal infections such as gastroenteritis (stomach upset) and dysentery (diarrhea). Another common type of bacteria found in human feces is Clostridium tetani, the bacteria that cause tetanus. People with wounds or scratches that have been exposed to flood waters should seek medical attention, as bacteria, viruses, protozoans and worms can enter the body through such breaks in the skin.
Children should not be allowed to swim or play in or around stormwater collection drains or outfalls, or other questionable bodies of water. Children and immuno-suppressed people are at increased risk of becoming ill if they are exposed to flood waters.
Any sewage backup into a residence must be properly cleaned to minimize the risk of disease. Floors should be cleaned with a 10% bleach solution (or other comparable commercially available disinfectant). Caution must be exercised not to mix bleach with any other household cleaners, as fumes can cause injury. Contaminated carpets should be replaced or cleaned by a professional cleaning contractor. Contaminated skin should be washed thoroughly with warm soapy water for a minimum of ten (10) minutes. DPH recommends that carpet and upholstered furniture damaged by floodwaters should be discarded. If cleaning laundry, wash items separately in hot water with a 10% bleach solution, or color-safe bleach.
Delaware residents served by public water systems should flush all water lines, including hot water lines, thoroughly. Ask water companies if they are disinfecting the water lines. Private well owners should have a licensed plumber or well driller disinfect the well and have it tested before using the water for cooking, drinking, washing and bathing.
Bacteria and mold can present health dangers indoors long after the floodwaters recede. Poor indoor air quality can lead to various health issues including respiratory problems, allergies, and can continue to damage building materials long after the floodwaters have receded. Prompt and proper clean up is important to eliminate possible or continued mold and bacterial growth.
Since many of the microorganisms, which can cause health effects, need moist environments to survive, water should be pumped, swept, or otherwise removed from inside the building. Be sure to thoroughly dry the building through the use of fans, dehumidifiers (if it is safe to use electricity), and opening of windows to increase air circulation. Carbon monoxide levels from fossil fuels can build up if gasoline-powered generators, camp stoves and lanterns, or charcoal-burning devices are used indoors. Carbon monoxide is a colorless, odorless, gas that can be deadly at high levels. Do not use combustion devices designed for outdoor use indoors. If the power is out, carbon monoxide detectors without batteries will not function.
Drying can usually be successful during the first 24 to 48 hours following water contamination. After that time period, removing wet materials is usually the best option. It may be necessary to remove portions of walls, ceilings, and floors to fully accomplish a complete drying out of the house. Certain building materials (for example, wallboard, fiberglass, insulation, and wall-to-wall carpeting) that were soaked only with clean rainwater may be able to be saved if dried properly and completely.
For more information or other public health concerns, contact the Division of Public Health at 1-888-459-2943.