/Safety Precautions During and After Floods

Safety Precautions During and After Floods

The Southern Nevada Health District is providing information to deal with the health implications regarding safety and property during and after flash floods.

Water Quality

Residents who use private wells for their drinking water should be safe unless a large amount of erosion at the well head occurred, or the well head was under water for any period of time. If a change in the color or taste of the water is noted, or if the well head was covered by water, it should be boiled vigorously for two to five minutes to use for drinking and cooking. Additionally, the well should be sanitized.

Most wells in the valley are approximately 400 feet deep and are 8-5/8 inches diameter. Wells may be sanitized by contracting a water well professional or by pouring one gallon of household bleach into the well and turning the pump on and off two or three times to mix the bleach and water. Then faucets in the house should be turned on until a bleach odor is detected. This should be done for each faucet in the house. Once this step is completed water must be left off for at least five hours. At the end of this time period the system should be flushed.

The system can be flushed by turning on the lawn irrigation system until no bleach odor is detected. After this time faucets in the house can be flushed. Flushing in this manner will not damage a septic system.

To test for bacteria in the water contact Quest Diagnostics at (702) 733-3790. Quest will provide bottles for testing, instruction on sample collection and information on associated costs.

Food Safety

If the flood waters reach into the garage or home, or affect any food establishments, food safety can also be an issue. The Centers for Disease Control and Prevention (CDC) provides excellent guidelines as to what food is safe to keep and what food should be discarded.

Do not eat any food that may have come into contact with the flood water unless it is in a hermetically sealed container that can be disinfected using a bleach solution of one cup of bleach in 5 gallons of water.

Anything with a twist off or crimped lid should be discarded. Do not keep any food or formula for use by infants regardless of packaging. Infants are at a much higher risk than the general public of contracting a disease carried by flood water.

If the flooding results in a power outage, protect frozen or refrigerated food by keeping the doors to the refrigerator/freezer closed at all times, or seek an alternate location with power to store the food.

Do not keep food that has been at room temperature for more than two hours. The best rule of thumb with refrigerated foods is “When in doubt, throw it out.”

Learn more about food safety during and after a power outage.

Restaurants and other food establishments directly affected by flooding, including power loss, must not operate during the crisis and must follow all guidelines outlined by the Southern Nevada Health District before reopening.

Clean up and Personal Hygiene

Do not allow your children to play in the flood waters or with any of the rocks, mud, or debris generated by the flooding. The water may be full of filth, including raw sewage from failed lift stations, sewers or septic systems, which can cause serious illness or injury to children.

Anyone coming into contact with the water or its contents, should apply the following good personal hygiene practices:

Wash hands with soap and warm, clean water for at least 20 seconds before preparing or eating food, after toilet use, after participating in any flood cleanup activities, and after handling articles contaminated with flood water or sewage.

Clean up should be performed as soon as possible:

  • Walls, hard-surfaced floors, and many other household surfaces should be cleaned with soap and water and disinfected with a solution of 1 cup bleach to 5 gallons of water.
  • Be particularly careful to thoroughly disinfect surfaces that may come in contact with food, such as counter tops, pantry shelves, refrigerators, etc.
  • Areas where small children play should also be carefully cleaned.
  • Wash all linens and clothing in hot water, or dry clean them.
  • For items that cannot be washed or dry cleaned, such as mattresses and upholstered furniture, air dry them in the sun and then spray them thoroughly with a disinfectant.
  • Steam clean all carpeting.
  • If there has been a backflow of sewage into the house, wear rubber boots and waterproof gloves during cleanup.
  • Remove and discard contaminated household materials that cannot be disinfected, such as wallcoverings, cloth, rugs, and drywall.

Other hazards must also be considered, especially during flash flooding.

Swiftly Flowing Water

If you enter swiftly flowing water, you risk drowning – regardless of your ability to swim. Swiftly moving shallow water can be deadly, and even shallow standing water can be dangerous for small children.

Cars or other vehicles do not provide adequate protection from flood waters. Cars can be swept away or may break down in moving water.


Wild animals may be forced from their natural habitats by flooding, and many domestic animals are also without homes after the flood. Take care to avoid these animals, because some may carry rabies.

Remember, most animals are disoriented and displaced, too. Do not corner an animal. If an animal must be removed, contact your local animal control authorities.

The Health District can provide information about the types of wild animals that carry rabies in your area.

Rodents may be a problem during and after a flood. Take care to secure all food supplies, and remove any animal carcasses in the vicinity by contacting your local animal control authorities.

If you are bitten by any animal, seek immediate medical attention. If you are bitten by a snake, first try to accurately identify the type of snake so that, if poisonous, the correct anti-venom may be administered.

Chemical Hazards

Use extreme caution when returning to your area after a flood. Be aware of potential chemical hazards you may encounter during flood recovery. Flood waters may have buried or moved hazardous chemical containers of solvents or other industrial chemicals from their normal storage places.

If any propane tanks (whether 20-pound tanks from a gas grill or household propane tanks) are discovered, do not attempt to move them yourself. These represent a very real danger of fire or explosion, and if any are found, police or fire departments or your State Fire Marshal’s office should be contacted immediately.

Car batteries, even those in flood water, may still contain an electrical charge and should be removed with extreme caution by using insulated gloves. Avoid coming in contact with any acid that may have spilled from a damaged car battery.

Flash floods can cause enormous damage in a short amount of time, yet recovery may be a long process. Take care of your family’s and your personal health and safety during this stressful time.

Please contact the Health District with any specific questions not answered here. Many excellent links about flood safety are available on our Related Links webpage.

Disinfecting a Flooded Well

The Health District is providing information to deal with the health implications regarding safety and property during and after flash floods.

Any well that was surrounded with flood water for any length of time should be disinfected before it is used for drinking or cooking purposes. Contaminated water can enter the well through cracks in the casing and seals. Even if the water from the well is clear, it may be contaminated with bacteria that can cause illness. The documents provided below from the Nevada Cooperative Extension provide instructions to homeowners on why and how to disinfect their well.

Once a well has been disinfected, the well water should be tested for coliform bacteria using a laboratory that is on the provided list of certified labs. If the test indicates that no coliform bacteria is present in the sample, the homeowner can resume using the water for drinking and cooking purposes. If the test indicates that coliform bacteria are present, the homeowner can either retest the water or do another round of disinfecting the well. Coliform bacteria are not found in ground water.

Please refer to the useful links below:

Southern Nevada Certified Water Testing Laboratories pdf 71KB

Shock Chlorination pdf 1.13MB

The reason for shock and testing pdf 235 KB

Estimating the amount of bleach to be used pdf 532KB

Links about flood safety are available on our Related Links webpage.

Contact Information

(702) 759-1320

Updated on: February 9, 2022

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