WARNING: Rapid snow melt and seasonal rains cause concerns for flood contaminated well water

The Allamakee County Department of Environmental Health warns area residents that recent flooding caused by the rapid melting of snow and seasonal rains may cause concerns with well water contamination. Allamakee County Environmental Health Director/Sanitarian Laurie Moody offers the following information regarding well water contaminated by flooding:

• Do not drink or wash with flood-contaminated well water. People who drink, wash with, or prepare food with water from a water supply influenced by flood water can get very sick.

• Do not attempt to work on the well, the well pump, or the water system. There is a real danger of electrical shock, personal injury or death plus well, well pump, and water system damage.

• If your private water well is, will be, or has been exposed to flooding conditions, you should contact the Allamakee County Sanitarian or a Department of Natural Resources (DNR) Certified Well Contractor for assistance in determining the safety of your well and water distribution system.

All wells located in areas where flood waters can reach, or wells located in areas where the groundwater can be influenced by flood waters, should be viewed as unsafe for drinking and other normal household uses until the well water has been sampled at a state certified lab and the sample results state that the well water is safe to use as drinking water.

If you suspect that your drinking water is contaminated, you should immediately stop using the water for drinking, ice making, cooking and bathing. You should temporarily switch to a known safe source of water such as a neighbor’s well that you know is safe, a city water supply, or purchased bottled water.

If you do not have a source of safe water, you can boil clear well water for at least two to three minutes at a rolling boil and then let the water stand until cool before use. Be aware that boiling water can increase the concentration of certain other contaminants, you should only consume boiled water when an alternative source of safe drinking water is not available.

Flooding events and higher than usual groundwater levels caused by unusually heavy rain or rapid snow melting can present major health risks. The surface and shallow groundwater can contaminate your water well and the aquifer it uses. This is especially true if your well is located in or is very near a floodway. Because of this, you should be aware of flood related conditions that pose a risk for your family’s health and only use drinking water that is from a known safe water source.

• Why should I worry about my well during flood situations?
- What you can’t see can harm you. Wells can be contaminated, even if there is no apparent damage and the water looks clear. Older wells may have hidden construction or age-related defects (shallow or poorly constructed casing or holes in the casing) that allow flood water to enter the well and contaminate the water.
- If the well casing is not finished at least one foot above the highwater level or it is not sealed with a tight fitting well cap, flood water and sediment may enter through the top of the well and cause contamination.
- Sediment found in the flood waters can enter the well through well vents and leaky wiring conduits causing contamination of your water source. The sediment can settle to the bottom of the well where it plugs the aquifer and require expensive well clean-outs using large equipment.
- Bacteria, viruses, farm and industrial chemicals, and other contaminants like manure and raw sewage can be contained in floodwaters also. This contaminated water can enter the well casing through the top of your well or through defects in the well’s casing. Contaminants can migrate underground to your well via sinkholes, a neighbor’s flooded well or unplugged wells. Such contamination can make your water unsafe for drinking, ice making, food preparation, cooking, bathing and other normal home uses.
- Flood water can also carry large debris that can hit the well and loosen well hardware, dislodge well vents and caps, or distort and damage well casing and pumping system.

• My well has electrical connections - can this be a hazard?
- Shock hazards do exist with components associated with wells. Do not attempt to work on a wet electrical system.
- After the flood waters have receded, the pump and electrical system need to be thoroughly dried and evaluated for damage. You should hire an Iowa DNR Certified Well Contractor to ensure that your water system is safe to operate. This inspection should look at all of the protections required for the type of well you are using. Any deficiencies should be addressed to reduce the potential for future well-related problems.
- Always get assistance in starting a well pump after a flood event. Do not turn on the pumping equipment until the pump’s electrical system has been checked by an Iowa DNR Certified Well Pump Installer.

• How do I clean up my well?
- Once the pumping system can be safely energized, the well should be pumped until the water appears clear for an extended period of time - this is especially important if the well exhibits dirty or turbid water during the initial minutes of operation. Please note that not all wells are capable of producing water for long periods of time - you can damage a pump if you are not careful and observant.
- Shock Chlorination is necessary to disinfect the well, the pressure tank and the distribution system before the well is put back into service.
- A chlorine solution of at least 200 mg/L (or one gallon of house hold bleach for every 100’ of well depth) should be introduced into the water well from the top and should be pumped through the entire water column and water system including all faucets, hot water heaters, toilet tanks, ice makers, yard hydrants and livestock waterers that are connected to your water supply system.
- The chlorine solution should sit in the well and the entire water system for a period of four to eight hours before additional water is used.
- The chlorine solution must be pumped out of the well and water system before the well water can be tested and the water used. Be sure to not send this heavily chlorinated water down your house drains to your septic system. Flush water to waste outdoors first until the smell of chlorine is no longer strong, then begin to flush the interior faucets. For severe flood related contamination, the well may require additional shock chlorinations.
- Chlorination of a water well that has been flooded should be done by an Iowa DNR Certified Well Contractor. For lists of certified well contractors and to request a water sample on your private water well, contact the Allamakee County Environmental Health Department at 563-568-4104.
- In some cases the well will require a thorough cleaning by an Iowa DNR Certified Well Contractor before the water can be tested and the well placed back into service.

• How do I know if my water is safe to drink again?
- All wells and water systems that have been influenced by flood waters of any kind, should be considered unsafe for use as drinking water until you submit a water sample to an Iowa DNR Certified Laboratory and the laboratory report states that the water is safe to drink.
- Even if a well has been shock chlorinated, you should not drink or otherwise consume the water until the lab report states the well is safe to use as drinking water. Even after a safe report, a follow-up sample is recommended in a few months.
- Remember that just because the water looks clean and clear does not mean that it is quality water and can be safely consumed.

• Additional information about flooded wells and safe well water can be found through:

United States Environmental Protection Agency (EPA)
- Private Drinking Water Wells: www.epa.gov/safewater/privatewells
- What to Do After a Flood: www.epa.gov/privatewells/protect-your-homes-water#what
- Emergency Disinfection of Water: www.epa.gov/ground-water-and-drinking-water/emergency-disinfection-drink...

State Hygienic Laboratory at The University of Iowa
- Frequently asked questions: www.shl.uiowa.edu/env/privatewell/faq.xml
- Testing of your drinking water: www.shl.uiowa.edu/env/privatewell/ordering.xml
- Flood Health and Safety: www.shl.uiowa.edu/env/privatewell/floodsafety

You may also contact Laurie Moody, Allamakee County Environmental Health Department Sanitarian at 563-568-4104 to schedule a water sample of your private well. There is a $10 charge to collect and  mail in samples for Total Coliform Bacteria, e’Coli Bacteria and Nitrates.