Written by Pete Fandel
Wednesday, 09 July 2008 10:34
Wells that have been contaminated with flood waters will likely need to be disinfected to eliminate bacteria in the system. Shock chlorination is one method that can be used. Extension Educator Duane Friend says that to effectively disinfect a well and plumbing system, the entire system must be involved. Once the likelihood of flood waters entering the system is gone, chlorination can be initiated. The process should allow the chlorinated water to be in the system for at least 12 hours, preferably overnight. Chlorine bleach or granules can be used. Do not use “fresh scent” or special bleaches. Be careful when handling chlorine. Wear rubber gloves, goggles and a protective apron when mixing chlorine.
For drilled wells, the top of the well casing will have to be disassembled. For dug wells, simply open the cover, and add the disinfectant. The amount of disinfectant required is determined by the amount of water in the well. For example, a well 5 feet in diameter that has 30 feet of water would require 8.5 gallons of bleach. A table that shows the amount of chlorine to use can be requested through local Extension offices. The chlorine should be added to about 10 gallons of water, and poured into the well—covering as much of the walls as possible.
All faucets in the home should then be turned on until a strong odor of chlorine is noticeable at each faucet. Afterwards, water flow should be stopped for at least 12 hours. It is usually easiest to do this as a late evening and overnight activity.
After allowing the chlorine to sit in the lines, all the faucets should be opened until the chlorine odor disappears. Faucets that drain into septic systems should only be turned on to low flow, to avoid overloading the system. Once this procedure is completed, the water should be used for a week or two and then tested by sending in a sample to a water testing lab.
For more information on disinfecting water lines, visit the University of Illinois Disaster Resources website at http://web.extension.uiuc.edu/disaster/facts/disinfec.html