On this page:

Private well flooding
Drinking water
Food safety
Information in other languages

Private well flooding

If you suspect that your well has been affected by flood waters, the Oregon Public Health Division, Office of Environmental Public Health (OEPH) recommends that you boil your water, or obtain water known to be safe from another source until you are sure your well is safe. Water should be boiled for one minute after it comes to a rolling boil. However, boiling water will not address all contamination. For example, boiling may actually concentrate nitrate levels. The best way to determine if the well has been contaminated is to have it tested for coliform bacteria, nitrate, and any other pollutants of concern by an accredited drinking water laboratory. Please contact OEPH for guidance on selecting a lab and pollutants for testing.

Signs of contamination

• Cloudy or muddy water, flooded well houses or submerged well casing seals are signs that your well might have been contaminated by flood water.
• If there is doubt about the safety of your water, it should not be used for drinking, brushing teeth, preparing food, making ice or mixing beverages. It can probably be safely used for all other household purposes.

Disinfecting well water

• If the water from your well is clear you can disinfect the water taken from the well by adding 8 drops of chlorinated household bleach to each gallon of water and allowing it to stand for at least 30 minutes.
• This is recommended for water that would be temporarily used for drinking, brushing teeth, washing dishes and for other food preparation activities.

Private well sanitation

• If the well has an electrical pump, turn off all electricity and clear debris from the well. If electrical connections appear wet or damaged, get assistance from a well or pump contractor to avoid the risk of shock.
• After the floodwater has subsided from the well vicinity, pump the well until the water runs clear. Use the outside faucet nearest the well to drain water from the well. If no pump is installed, bail water with a bucket until water is clear.
• Disinfect the well with household bleach and then test it to be sure it is free of bacterial contamination and any other pollutants of concern. Steps for disinfecting your well are as follows:

• Find and remove from the top of the well casing, the inspection plug. If there is not an inspection plug, you may be able to remove the air-vent line or you may be able to remove a plug or valve from the water line itself somewhere near the top of the seal.
• Many wells have a foot valve that prevents addition of anything through the water line itself.
• You may need to contact your pump supplier for advice about how to get bleach into the well.
• If the casing of your well is not airtight before you remove the plug, it is very likely that the well will continue to be contaminated even without flooding. There should be no unplugged openings through the seal.

Additional Resources

• Private well fact sheet (PDF)
• How to disinfect a well fact sheet (PDF)
• Oregon Department of Environmental Quality - Disaster Cleanup
• U.S. Centers for Disease Control & Prevention: Well Testing
• U.S. Centers for Disease Control & Prevention: Disinfecting Wells After a Disaster
• U.S. Environmental Protection Agency: What To Do After The Flood

Back to top 

Drinking Water

During storm events, water purification systems may not be functioning fully. Safe water for drinking, cooking, and personal hygiene includes bottled, boiled, or treated water. Your state, local, or tribal health department can make specific recommendations for boiling or treating water in your area. Here are some general rules concerning water for drinking, cooking, and personal hygiene.

Remember:

• Do not use contaminated water to wash dishes, brush your teeth, wash and prepare food,  make ice, or make baby formula. If possible, use baby formula that does not need to have water added.
• If you use bottled water, be sure it came from a safe source. If you do not know that the water came from a safe source, you should boil or treat it before you use it. Use only bottled, boiled, or treated water until your supply is tested and found safe.
• Boiling water, when practical, is the preferred way to kill harmful bacteria and parasites. Bringing water to a rolling boil for 1 minute will kill harmful organisms.
• If you don’t have clean, safe, bottled water and if boiling is not possible, you often can make water safer to drink by using a disinfectant, such as unscented household chlorine bleach, iodine, or chlorine dioxide tablets. These can kill most harmful organisms, such as viruses and bacteria. However, only chlorine dioxide tablets are effective in controlling more resistant organisms, such as the parasite Cryptosporidium.

To disinfect water:

• Filter it through a clean cloth, paper towel, or coffee filter OR allow it to settle.
• Draw off the clear water.
• When using household chlorine bleach:
• Add 1/8 teaspoon (or 8 drops; about 0.625 milliliters) of unscented liquid household chlorine (5–6%) bleach for each gallon of clear water (or 2 drops of bleach for each liter or each quart of clear water). Add 1/4 teaspoon (or 16 drops; about 1.50 milliliters) of bleach for each gallon of cloudy water (or 4 drops of bleach for each liter or each quart of cloudy water).
• Stir the mixture well.
• Let it stand for 30 minutes or longer before you use it.
• Store the disinfected water in clean, disinfected containers with tight covers.
• When using iodine:
• Follow the manufacturer’s instructions.
• Store the disinfected water in clean, disinfected containers with tight covers.
• When using chlorine dioxide tablets:
• Follow the manufacturer’s instructions.
• Store the disinfected water in clean, disinfected containers with tight covers.