Water and Septic Precautions During and After Flooding

During flood events in Polk County, homes can experience flooding in their basements. Often the source of this flooding is from sewage or combined storm water systems that have become overwhelmed because of regional flooding. It is best to assume that any flood water may contain dangerous bacteria or chemicals. If possible, avoid contact with flood water. If you must work in flood waters, wearing boots, gloves and protective clothing will offer increase protection. Wash with soap and water as soon as possible after exposure to reduce your risk of becoming ill. Some cities offer a program to assist home owners in installing backflow protection on drains. You should contact your city public utilities for more information if this program exists in your area.

As flooding continues to be prominent throughout the County, Polk County Environmental Health is advising private well owners to take precautions for their drinking water. If your well has been flooded, it could have become contaminated with bacteria or other contaminants and not be a safe source of drinking water. Environmental Health recommends that you boil your water or obtain drinking water from another source until you are sure your well is safe. To be considered safe, water should be boiled for at least one minute after it comes to a rolling boil.

Cloudy or muddy water are signs that your well might have been contaminated by flood water, surface water or shallow groundwater. If there is doubt about the safety of your well water, it should not be used for drinking purposes or preparing food. The best way to determine if the water from your well is safe is to have it sampled and tested for coliform bacteria by an approved drinking water laboratory.

The following are guidelines to disinfect your well water supply and minimize the risks of contamination. Prior to any maintenance work, have a qualified electrician or well/pump contractor restore any electrical services that have been turned off due to the flood.

How to disinfect your well water after the floods:

• If your water is muddy or cloudy, run the water from an outside spigot with a hose attached until the water becomes clear and free of sediments.
• Determine what type of well you have and how to pour bleach into the well. Some wells have a sanitary seal with either an air vent or a plug that can be removed for pouring the bleach into the well.
• For many private wells, mixing 4 cups of bleach with 5 gallons of water will be enough to treat 200 gallons of water which yields approximately 50 ppm or 50mg/L. Carefully pour the bleach down into the well casing using a funnel if needed.
• After the bleach has been added, run water from an outside hose into the well casing until you smell chlorine coming from the hose. Then turn off the outside hose.
• Turn on all cold water faucets, inside and outside of house, until the chlorine odor is detected in each faucet, then shut them all off.
• Wait at least 8 hours before turning the faucets back on. It is important not to drink, cook, bathe or wash with this water during the time period --- it contains high amounts of chlorine.
• Turn on all faucets and thoroughly flush the system until there is no longer a chlorine odor.
• Have your water tested for bacteria at least 5 days after disinfection.
• Sample for total coliforms. A good sample location is a bathroom faucet with the aerator removed. Wait until lab results are negative for total coliform before using the water for drinking or eating purposes.

Note: Well disinfection will not provide protection from pesticides, heavy metals and other types of non-biological contamination. If such contamination is suspected, special treatment is required.

Septic Systems Maintenance after Flooding. Minimizing the Risk of Well Water Contamination

• Do not use the sewage system until water in the soil absorption field is lower than the water level around the house.
• Have your septic tank professionally inspected and serviced if you suspect damage. Signs of damage include settling or an inability to accept water. Most septic tanks are not damaged by flooding since they are below ground and completely covered. However, septic tanks and pump chambers can fill with silt and debris, and must be professionally cleaned. If the soil absorption field is clogged with silt, a new system may have to be installed.
• Do not compact the soil over the soil absorption field by driving or operating equipment in the area. Saturated soil is especially susceptible to compaction, which can reduce the soil absorption field’s ability to treat wastewater and lead to system failure.

For more information about protecting private wells:

• OSU Extension Service Well Water Program:  1-541-737-6294. http://wellwater.oregonstate.edu
• EPA: Safe Drinking Water Hotline:  1-800-426-4791.
• Water Systems Council Wellcare® Hotline:  1-888-395-1033. 
• EPA Website:  https://www.epa.gov/privatewells
• DEQ:  http://www.oregon.gov/deq/wq/Pages/default.aspx 1-800-452-4011
• Oregon Health Authority (OHA) Drinking Water Program:  1-971-673-0405
  http://public.health.oregon.gov/HealthyEnvironments/DrinkingWater/Pages/...