Contaminants Lurking In Flood Waters Could Pose Health Risks

Jan 8, 2017


During a flood, safety precautions like staying away from and not driving through flooded areas are the primary concerns Health Officer Kevin Dick is with the Washoe County Health District. He says people should also avoid coming into contact with flood waters, which could be contaminated and can pose several public health risks.

“People should presume that any flood waters that they see are contaminated with sewage, so it could be full of pathogens,” Dick explains, “and not something you want to be in contact with.”

Reno Public Radio’s Anh Gray talks with Kevin Dick about the contaminants that could be lurking in flood waters. Dick also advises people who have homes with private wells and septic systems to take extra steps to avoid risks.


The Washoe County Health District, the Washoe County Emergency Management and Federal Emergency Management Agency (FEMA), issued the following guidelines.

For additional information, click here:


Flood information to protect your personal health and safety

Water Quality – Contamination of Drinking Water

Listen to public announcements and monitor social media on the safety of municipal water supplies.

Flooded private water wells should not be used during a flood and may need testing and disinfecting after flood waters recede. If property is served by a residential domestic well:

• Inspect the well head for damage. If well shows any sign of damage, including being subjected to high heat, contact a licensed well driller or plumber to evaluate the well prior to restarting the well.

• Remove the well cap and inspect the seal as follows:

• If there is any damage to the seal, contact a licensed well

driller or plumber to replace the seal prior to restarting the well.

1. If the well seal is free of damage, disinfect the seal, well head and cap and replace the seal and cap with a 10% household bleach solution. Flush water through the home fixtures until such time as there are no signs of bleach odor in the water.

2. Inspect any pressure or storage tanks for damage, if damage is present or possible, contact a licensed well driller or plumber to have the system evaluated and repaired.

Water for Drinking and Cooking

Water that is safe for drinking includes bottled water, boiled, or treated water. The Health District makes specific recommendations for boiling or treating water. Some general rules for drinking and cooking are:

• Do not use contaminated water to wash dishes, brush teeth, wash and prepare food or make ice.

• If you use boiled water, be sure it comes from a reliable source, otherwise boil or treat it again. Drink only bottled,

boiled or treated water until your supply is tested and found safe.

• Boiling water kills harmful bacteria and parasites. Bringing water to a boil for 5 minutes will make it suitable for

drinking and preparing food.

• Water may be treated with chlorine by mixing 1/8 teaspoon of unscented ordinary chlorine bleach per gallon of water.

Mix the solution thoroughly and let stand for 30 minutes. Be aware, that treatment like this will not kill parasitic

organisms like giardia or cryptosporidium.

• People who are immunocompromised should drink only bottled water or from a source approved by their physician.

• Containers for water should be rinsed with a bleach solution before reuse.

If property is served by an engineered septic system or system requirements, electricity to pump wastes:

• Evaluate all components of the residential septic system for possible damage, including but not limited to pump chambers and overflow alarm systems. If the system is unable to pump sewage to the treatment field, contact a licensed plumber or engineer for system evaluation.

• Ensure all electrical components of the system are functioning.

Food Safety

Do not eat food that has come in contact with flood water. Discard any food without a waterproof container if there is a chance that it came into contact with water.

Undamaged commercially-canned foods can be salvaged by removing the can label and cleaning the can with the bleach solution.

Food contained with screw caps, crimped caps, pop tops twist tops, and home canned foods should be discarded if they come in contact with water because they cannot be disinfected.

Do not use powdered formulas prepared with water treated with chlorine bleach.

Frozen and Refrigerated Foods

Your refrigerator will keep foods cool for about 4 hours without power if the doors are not opened. If your refrigerator or freezer is without power for a long period:

• Divide your frozen foods among friends if they have power

• Seek freezer space in a store, church, school, or commercial freezer that has power

• Use dry ice. (25 lbs of dry ice will keep a 10 cubic foot freezer below freezing for 3-4 days.)

Thawed food can usually be eaten if the food is 40 degrees Fahrenheit or colder or if it still contains ice crystals. Remember, “When in doubt, throw it out.” A wide variety of food borne illnesses can result from improperly stored and contaminated foods. Thoroughly clean with water and soap all interiors of all refrigerators and freezers, then disinfect them with a 10% household bleach solution and allow to air dry.



Walls, hard-surfaced floors and household surfaces should be cleaned with soap and water and disinfected with a solution of one ounce bleach (1/8 cup) and five gallons of water, paying particular attention to 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 clothes in hot water or have them dry cleaned. For items that cannot be washed or dry cleaned, dry items in the sun then spray items with disinfectant. Steam clean carpeting.

If there has been sewage back up into the house wear rubber boots and waterproof gloves during clean up. Remove and discard contaminated household materials that cannot be disinfected such as all coverings, cloth, rugs, and drywall.

Other Hazards

Swift flowing water

If you enter swift flowing water you risk drowning regardless of your ability to swim. Swift-moving shallow water can be deadly, and any water can be dangerous for small children. Cars or other vehicles do not provide adequate protection from flood waters and can be swept away or break down in the moving water.


Make a plan for where you’ll take your animals and pets if you are affected by a flood. Hopefully you have food and water for them in your emergency supply kit. Many wild animals may be displaced due to floods as well as domesticated animals that will be forced into new environments. These displaced and disoriented animals can be dangerous. Do not corner an animal. If animal needs to be removed call your local animal control for help.

Chemical Hazards

Always use extreme caution when around chemicals and hazardous materials, especially during or after a flood. Flood waters may have buried, moved or mixed hazardous chemicals. Items like propane tanks and car batteries can cause fire, explosion, or electrical shock.