Shock Chlorination is preformed to kill bacteriological growth to prevent sickness and eliminate unwanted tastes and odors from your well. The process of shock chlorination is not that difficult but if the procedure is not completed properly it may be ineffective. There is more then one way to shock the well. The Saskatchewan Research council (SRC) recommends that you use a 1200 litre water tank to hold water that can be treated and re-released back into the well. SRC SITE This is a great way to do it but few of us have such a large water tank so I am going to explain how I do it.
First of all it is important to understand a few things before you start. Plan to save enough water to last about 12 hours. Chlorine such as household bleach will do the job but it also will negatively affect some water treatment equipment so be sure to turn all water equipment to bypass to keep the super bleached water from entering the filters. If you are unsure how to do this contact the supplier of the filter for more info. The other issue you can face after chlorinating the well might be chunks of debris coming off the pipes and plugging up the screens on your water spouts. It is recommended that you turn off your hot water tank, you will later drain the tank and re-fill it with fresh treated water.
The goal is to get the bleached water to all the fixtures in the home and the well. So here is how I do it. After I have completed the filter bypass I hook a hose to the hydrant (or outside tap) and begin running the water. I make sure my hose will easily reach the well head. I then add about 4 gallons of regular or extra strength bleach to the well through the top. Be sure not to buy scented bleach, you want the original brand. It doesn’t matter if you have a dug well or a bored well. Just make sure that the garden hose is in the well and let it run for at least two hours with the bleach in the water.
Next you want to turn off the hot water tank so it doesn’t fire up or turn on the element when you run the hot water. Then run all the cold and hot water taps until the smell of bleach is strong in each. Finally leave the system to work on the bacteria over the next 12 hours.
TIP: I start the whole process in the late afternoon so it can have a good 12 hours to kill and clean the unwanted bacteria in the water. In the morning you will drain the hot water tank into the floor drain and begin running the garden hose into an area that won’t kill any plants or trees to clear the well of the chlorine. Finally all the fixtures should be run to to clear the lines inside the home until the smell of bleach is gone. It often takes a day or so for the water to completely return to its natural clear color. Don’t for get to turn on the hot water tank again. You will now be able to turn the filters back into active service if the chlorine is mostly gone.
TIP: Often after the shock treatment there will be black slime and chunks of debris coming out of the spouts. I usually take the screen filters off the spouts so they don’t plug up.
Let me know if this all makes sense, if not I can rewrite parts to be more clear.
UPDATE: I recently shocked my well and caused problems with my pump because I stirred up the well too much. The sediment I stirred up partially plugged the screen in the pump causing it to overheat and trip the overload. Fortunately for me the pump is quite new and has the overload protection it needed to protect itself. When I released the 100 gallons from the above ground tank I should have let it go more slowly. The goal of the stored water is to force the bleached water into the formation by filling the well more then it is normally. So remember if you do this to slowly add the water to the well. Here is a site I came across that might shed some more light on the process as well. SHOCK CLORINATION