One of the most common methods to remove coliform bacteria from a ground water supply is by disinfecting the water source. Shock chlorination gets rid of coliform as well as iron and sulfur bacteria that tend to affect the color and taste of the water.
While municipalities test their water supplies to determine whether or not contaminants exist, owners of water wells must test and maintain their own water sources. Shock chlorination involves adding a strong chlorine solution directly into the water source. The solution must be concentrated enough to raise the level of chlorine in the water source to 200 milligrams per liter.
It is also important for the plumbing to be cleaned as well. If the well utilizes a pump, it should be operated for long enough to allow the chlorinated water to pass through the entire system. However, if the pump uses an activated carbon filter, remove it prior to administering the shock chlorination. Otherwise, the activated carbon filters much of the chlorine, not only reducing the efficiency of the process, but also severely impairing the working life of the filter. Other mechanisms such as clean water softeners, iron removal filters and sand filters should be back-washed.